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1# orm/mapper.py
2# Copyright (C) 2005-2025 the SQLAlchemy authors and contributors
3# <see AUTHORS file>
4#
5# This module is part of SQLAlchemy and is released under
6# the MIT License: https://www.opensource.org/licenses/mit-license.php
7# mypy: allow-untyped-defs, allow-untyped-calls
9"""Logic to map Python classes to and from selectables.
11Defines the :class:`~sqlalchemy.orm.mapper.Mapper` class, the central
12configurational unit which associates a class with a database table.
14This is a semi-private module; the main configurational API of the ORM is
15available in :class:`~sqlalchemy.orm.`.
17"""
18from __future__ import annotations
20from collections import deque
21from functools import reduce
22from itertools import chain
23import sys
24import threading
25from typing import Any
26from typing import Callable
27from typing import cast
28from typing import Collection
29from typing import Deque
30from typing import Dict
31from typing import FrozenSet
32from typing import Generic
33from typing import Iterable
34from typing import Iterator
35from typing import List
36from typing import Mapping
37from typing import Optional
38from typing import Sequence
39from typing import Set
40from typing import Tuple
41from typing import Type
42from typing import TYPE_CHECKING
43from typing import TypeVar
44from typing import Union
45import weakref
47from . import attributes
48from . import exc as orm_exc
49from . import instrumentation
50from . import loading
51from . import properties
52from . import util as orm_util
53from ._typing import _O
54from .base import _class_to_mapper
55from .base import _parse_mapper_argument
56from .base import _state_mapper
57from .base import PassiveFlag
58from .base import state_str
59from .interfaces import _MappedAttribute
60from .interfaces import EXT_SKIP
61from .interfaces import InspectionAttr
62from .interfaces import MapperProperty
63from .interfaces import ORMEntityColumnsClauseRole
64from .interfaces import ORMFromClauseRole
65from .interfaces import StrategizedProperty
66from .path_registry import PathRegistry
67from .. import event
68from .. import exc as sa_exc
69from .. import inspection
70from .. import log
71from .. import schema
72from .. import sql
73from .. import util
74from ..event import dispatcher
75from ..event import EventTarget
76from ..sql import base as sql_base
77from ..sql import coercions
78from ..sql import expression
79from ..sql import operators
80from ..sql import roles
81from ..sql import TableClause
82from ..sql import util as sql_util
83from ..sql import visitors
84from ..sql.cache_key import MemoizedHasCacheKey
85from ..sql.elements import KeyedColumnElement
86from ..sql.schema import Column
87from ..sql.schema import Table
88from ..sql.selectable import LABEL_STYLE_TABLENAME_PLUS_COL
89from ..util import HasMemoized
90from ..util import HasMemoized_ro_memoized_attribute
91from ..util.typing import Literal
92from ..util.typing import TupleAny
93from ..util.typing import Unpack
95if TYPE_CHECKING:
96 from ._typing import _IdentityKeyType
97 from ._typing import _InstanceDict
98 from ._typing import _ORMColumnExprArgument
99 from ._typing import _RegistryType
100 from .decl_api import registry
101 from .dependency import _DependencyProcessor
102 from .descriptor_props import CompositeProperty
103 from .descriptor_props import SynonymProperty
104 from .events import MapperEvents
105 from .instrumentation import ClassManager
106 from .path_registry import _CachingEntityRegistry
107 from .properties import ColumnProperty
108 from .relationships import RelationshipProperty
109 from .state import InstanceState
110 from .util import ORMAdapter
111 from ..engine import Row
112 from ..engine import RowMapping
113 from ..sql._typing import _ColumnExpressionArgument
114 from ..sql._typing import _EquivalentColumnMap
115 from ..sql.base import _EntityNamespace
116 from ..sql.base import ReadOnlyColumnCollection
117 from ..sql.elements import ColumnClause
118 from ..sql.elements import ColumnElement
119 from ..sql.selectable import FromClause
120 from ..util import OrderedSet
123_T = TypeVar("_T", bound=Any)
124_MP = TypeVar("_MP", bound="MapperProperty[Any]")
125_Fn = TypeVar("_Fn", bound="Callable[..., Any]")
128_WithPolymorphicArg = Union[
129 Literal["*"],
130 Tuple[
131 Union[Literal["*"], Sequence[Union["Mapper[Any]", Type[Any]]]],
132 Optional["FromClause"],
133 ],
134 Sequence[Union["Mapper[Any]", Type[Any]]],
135]
138_mapper_registries: weakref.WeakKeyDictionary[_RegistryType, bool] = (
139 weakref.WeakKeyDictionary()
140)
143def _all_registries() -> Set[registry]:
144 with _CONFIGURE_MUTEX:
145 return set(_mapper_registries)
148def _unconfigured_mappers() -> Iterator[Mapper[Any]]:
149 for reg in _all_registries():
150 yield from reg._mappers_to_configure()
153_already_compiling = False
156# a constant returned by _get_attr_by_column to indicate
157# this mapper is not handling an attribute for a particular
158# column
159NO_ATTRIBUTE = util.symbol("NO_ATTRIBUTE")
161# lock used to synchronize the "mapper configure" step
162_CONFIGURE_MUTEX = threading.RLock()
165@inspection._self_inspects
166@log.class_logger
167class Mapper(
168 ORMFromClauseRole,
169 ORMEntityColumnsClauseRole[_O],
170 MemoizedHasCacheKey,
171 InspectionAttr,
172 log.Identified,
173 inspection.Inspectable["Mapper[_O]"],
174 EventTarget,
175 Generic[_O],
176):
177 """Defines an association between a Python class and a database table or
178 other relational structure, so that ORM operations against the class may
179 proceed.
181 The :class:`_orm.Mapper` object is instantiated using mapping methods
182 present on the :class:`_orm.registry` object. For information
183 about instantiating new :class:`_orm.Mapper` objects, see
184 :ref:`orm_mapping_classes_toplevel`.
186 """
188 dispatch: dispatcher[Mapper[_O]]
190 _dispose_called = False
191 _configure_failed: Any = False
192 _ready_for_configure = False
194 def __init__(
195 self,
196 class_: Type[_O],
197 local_table: Optional[FromClause] = None,
198 properties: Optional[Mapping[str, MapperProperty[Any]]] = None,
199 primary_key: Optional[Iterable[_ORMColumnExprArgument[Any]]] = None,
200 inherits: Optional[Union[Mapper[Any], Type[Any]]] = None,
201 inherit_condition: Optional[_ColumnExpressionArgument[bool]] = None,
202 inherit_foreign_keys: Optional[
203 Sequence[_ORMColumnExprArgument[Any]]
204 ] = None,
205 always_refresh: bool = False,
206 version_id_col: Optional[_ORMColumnExprArgument[Any]] = None,
207 version_id_generator: Optional[
208 Union[Literal[False], Callable[[Any], Any]]
209 ] = None,
210 polymorphic_on: Optional[
211 Union[_ORMColumnExprArgument[Any], str, MapperProperty[Any]]
212 ] = None,
213 _polymorphic_map: Optional[Dict[Any, Mapper[Any]]] = None,
214 polymorphic_identity: Optional[Any] = None,
215 concrete: bool = False,
216 with_polymorphic: Optional[_WithPolymorphicArg] = None,
217 polymorphic_abstract: bool = False,
218 polymorphic_load: Optional[Literal["selectin", "inline"]] = None,
219 allow_partial_pks: bool = True,
220 batch: bool = True,
221 column_prefix: Optional[str] = None,
222 include_properties: Optional[Sequence[str]] = None,
223 exclude_properties: Optional[Sequence[str]] = None,
224 passive_updates: bool = True,
225 passive_deletes: bool = False,
226 confirm_deleted_rows: bool = True,
227 eager_defaults: Literal[True, False, "auto"] = "auto",
228 legacy_is_orphan: bool = False,
229 _compiled_cache_size: int = 100,
230 ):
231 r"""Direct constructor for a new :class:`_orm.Mapper` object.
233 The :class:`_orm.Mapper` constructor is not called directly, and
234 is normally invoked through the
235 use of the :class:`_orm.registry` object through either the
236 :ref:`Declarative <orm_declarative_mapping>` or
237 :ref:`Imperative <orm_imperative_mapping>` mapping styles.
239 .. versionchanged:: 2.0 The public facing ``mapper()`` function is
240 removed; for a classical mapping configuration, use the
241 :meth:`_orm.registry.map_imperatively` method.
243 Parameters documented below may be passed to either the
244 :meth:`_orm.registry.map_imperatively` method, or may be passed in the
245 ``__mapper_args__`` declarative class attribute described at
246 :ref:`orm_declarative_mapper_options`.
248 :param class\_: The class to be mapped. When using Declarative,
249 this argument is automatically passed as the declared class
250 itself.
252 :param local_table: The :class:`_schema.Table` or other
253 :class:`_sql.FromClause` (i.e. selectable) to which the class is
254 mapped. May be ``None`` if this mapper inherits from another mapper
255 using single-table inheritance. When using Declarative, this
256 argument is automatically passed by the extension, based on what is
257 configured via the :attr:`_orm.DeclarativeBase.__table__` attribute
258 or via the :class:`_schema.Table` produced as a result of
259 the :attr:`_orm.DeclarativeBase.__tablename__` attribute being
260 present.
262 :param polymorphic_abstract: Indicates this class will be mapped in a
263 polymorphic hierarchy, but not directly instantiated. The class is
264 mapped normally, except that it has no requirement for a
265 :paramref:`_orm.Mapper.polymorphic_identity` within an inheritance
266 hierarchy. The class however must be part of a polymorphic
267 inheritance scheme which uses
268 :paramref:`_orm.Mapper.polymorphic_on` at the base.
270 .. versionadded:: 2.0
272 .. seealso::
274 :ref:`orm_inheritance_abstract_poly`
276 :param always_refresh: If True, all query operations for this mapped
277 class will overwrite all data within object instances that already
278 exist within the session, erasing any in-memory changes with
279 whatever information was loaded from the database. Usage of this
280 flag is highly discouraged; as an alternative, see the method
281 :meth:`_query.Query.populate_existing`.
283 :param allow_partial_pks: Defaults to True. Indicates that a
284 composite primary key with some NULL values should be considered as
285 possibly existing within the database. This affects whether a
286 mapper will assign an incoming row to an existing identity, as well
287 as if :meth:`.Session.merge` will check the database first for a
288 particular primary key value. A "partial primary key" can occur if
289 one has mapped to an OUTER JOIN, for example.
291 The :paramref:`.orm.Mapper.allow_partial_pks` parameter also
292 indicates to the ORM relationship lazy loader, when loading a
293 many-to-one related object, if a composite primary key that has
294 partial NULL values should result in an attempt to load from the
295 database, or if a load attempt is not necessary.
297 .. versionadded:: 2.0.36 :paramref:`.orm.Mapper.allow_partial_pks`
298 is consulted by the relationship lazy loader strategy, such that
299 when set to False, a SELECT for a composite primary key that
300 has partial NULL values will not be emitted.
302 :param batch: Defaults to ``True``, indicating that save operations
303 of multiple entities can be batched together for efficiency.
304 Setting to False indicates
305 that an instance will be fully saved before saving the next
306 instance. This is used in the extremely rare case that a
307 :class:`.MapperEvents` listener requires being called
308 in between individual row persistence operations.
310 :param column_prefix: A string which will be prepended
311 to the mapped attribute name when :class:`_schema.Column`
312 objects are automatically assigned as attributes to the
313 mapped class. Does not affect :class:`.Column` objects that
314 are mapped explicitly in the :paramref:`.Mapper.properties`
315 dictionary.
317 This parameter is typically useful with imperative mappings
318 that keep the :class:`.Table` object separate. Below, assuming
319 the ``user_table`` :class:`.Table` object has columns named
320 ``user_id``, ``user_name``, and ``password``::
322 class User(Base):
323 __table__ = user_table
324 __mapper_args__ = {"column_prefix": "_"}
326 The above mapping will assign the ``user_id``, ``user_name``, and
327 ``password`` columns to attributes named ``_user_id``,
328 ``_user_name``, and ``_password`` on the mapped ``User`` class.
330 The :paramref:`.Mapper.column_prefix` parameter is uncommon in
331 modern use. For dealing with reflected tables, a more flexible
332 approach to automating a naming scheme is to intercept the
333 :class:`.Column` objects as they are reflected; see the section
334 :ref:`mapper_automated_reflection_schemes` for notes on this usage
335 pattern.
337 :param concrete: If True, indicates this mapper should use concrete
338 table inheritance with its parent mapper.
340 See the section :ref:`concrete_inheritance` for an example.
342 :param confirm_deleted_rows: defaults to True; when a DELETE occurs
343 of one more rows based on specific primary keys, a warning is
344 emitted when the number of rows matched does not equal the number
345 of rows expected. This parameter may be set to False to handle the
346 case where database ON DELETE CASCADE rules may be deleting some of
347 those rows automatically. The warning may be changed to an
348 exception in a future release.
350 :param eager_defaults: if True, the ORM will immediately fetch the
351 value of server-generated default values after an INSERT or UPDATE,
352 rather than leaving them as expired to be fetched on next access.
353 This can be used for event schemes where the server-generated values
354 are needed immediately before the flush completes.
356 The fetch of values occurs either by using ``RETURNING`` inline
357 with the ``INSERT`` or ``UPDATE`` statement, or by adding an
358 additional ``SELECT`` statement subsequent to the ``INSERT`` or
359 ``UPDATE``, if the backend does not support ``RETURNING``.
361 The use of ``RETURNING`` is extremely performant in particular for
362 ``INSERT`` statements where SQLAlchemy can take advantage of
363 :ref:`insertmanyvalues <engine_insertmanyvalues>`, whereas the use of
364 an additional ``SELECT`` is relatively poor performing, adding
365 additional SQL round trips which would be unnecessary if these new
366 attributes are not to be accessed in any case.
368 For this reason, :paramref:`.Mapper.eager_defaults` defaults to the
369 string value ``"auto"``, which indicates that server defaults for
370 INSERT should be fetched using ``RETURNING`` if the backing database
371 supports it and if the dialect in use supports "insertmanyreturning"
372 for an INSERT statement. If the backing database does not support
373 ``RETURNING`` or "insertmanyreturning" is not available, server
374 defaults will not be fetched.
376 .. versionchanged:: 2.0.0rc1 added the "auto" option for
377 :paramref:`.Mapper.eager_defaults`
379 .. seealso::
381 :ref:`orm_server_defaults`
383 .. versionchanged:: 2.0.0 RETURNING now works with multiple rows
384 INSERTed at once using the
385 :ref:`insertmanyvalues <engine_insertmanyvalues>` feature, which
386 among other things allows the :paramref:`.Mapper.eager_defaults`
387 feature to be very performant on supporting backends.
389 :param exclude_properties: A list or set of string column names to
390 be excluded from mapping.
392 .. seealso::
394 :ref:`include_exclude_cols`
396 :param include_properties: An inclusive list or set of string column
397 names to map.
399 .. seealso::
401 :ref:`include_exclude_cols`
403 :param inherits: A mapped class or the corresponding
404 :class:`_orm.Mapper`
405 of one indicating a superclass to which this :class:`_orm.Mapper`
406 should *inherit* from. The mapped class here must be a subclass
407 of the other mapper's class. When using Declarative, this argument
408 is passed automatically as a result of the natural class
409 hierarchy of the declared classes.
411 .. seealso::
413 :ref:`inheritance_toplevel`
415 :param inherit_condition: For joined table inheritance, a SQL
416 expression which will
417 define how the two tables are joined; defaults to a natural join
418 between the two tables.
420 :param inherit_foreign_keys: When ``inherit_condition`` is used and
421 the columns present are missing a :class:`_schema.ForeignKey`
422 configuration, this parameter can be used to specify which columns
423 are "foreign". In most cases can be left as ``None``.
425 :param legacy_is_orphan: Boolean, defaults to ``False``.
426 When ``True``, specifies that "legacy" orphan consideration
427 is to be applied to objects mapped by this mapper, which means
428 that a pending (that is, not persistent) object is auto-expunged
429 from an owning :class:`.Session` only when it is de-associated
430 from *all* parents that specify a ``delete-orphan`` cascade towards
431 this mapper. The new default behavior is that the object is
432 auto-expunged when it is de-associated with *any* of its parents
433 that specify ``delete-orphan`` cascade. This behavior is more
434 consistent with that of a persistent object, and allows behavior to
435 be consistent in more scenarios independently of whether or not an
436 orphan object has been flushed yet or not.
438 See the change note and example at :ref:`legacy_is_orphan_addition`
439 for more detail on this change.
441 :param passive_deletes: Indicates DELETE behavior of foreign key
442 columns when a joined-table inheritance entity is being deleted.
443 Defaults to ``False`` for a base mapper; for an inheriting mapper,
444 defaults to ``False`` unless the value is set to ``True``
445 on the superclass mapper.
447 When ``True``, it is assumed that ON DELETE CASCADE is configured
448 on the foreign key relationships that link this mapper's table
449 to its superclass table, so that when the unit of work attempts
450 to delete the entity, it need only emit a DELETE statement for the
451 superclass table, and not this table.
453 When ``False``, a DELETE statement is emitted for this mapper's
454 table individually. If the primary key attributes local to this
455 table are unloaded, then a SELECT must be emitted in order to
456 validate these attributes; note that the primary key columns
457 of a joined-table subclass are not part of the "primary key" of
458 the object as a whole.
460 Note that a value of ``True`` is **always** forced onto the
461 subclass mappers; that is, it's not possible for a superclass
462 to specify passive_deletes without this taking effect for
463 all subclass mappers.
465 .. seealso::
467 :ref:`passive_deletes` - description of similar feature as
468 used with :func:`_orm.relationship`
470 :paramref:`.mapper.passive_updates` - supporting ON UPDATE
471 CASCADE for joined-table inheritance mappers
473 :param passive_updates: Indicates UPDATE behavior of foreign key
474 columns when a primary key column changes on a joined-table
475 inheritance mapping. Defaults to ``True``.
477 When True, it is assumed that ON UPDATE CASCADE is configured on
478 the foreign key in the database, and that the database will handle
479 propagation of an UPDATE from a source column to dependent columns
480 on joined-table rows.
482 When False, it is assumed that the database does not enforce
483 referential integrity and will not be issuing its own CASCADE
484 operation for an update. The unit of work process will
485 emit an UPDATE statement for the dependent columns during a
486 primary key change.
488 .. seealso::
490 :ref:`passive_updates` - description of a similar feature as
491 used with :func:`_orm.relationship`
493 :paramref:`.mapper.passive_deletes` - supporting ON DELETE
494 CASCADE for joined-table inheritance mappers
496 :param polymorphic_load: Specifies "polymorphic loading" behavior
497 for a subclass in an inheritance hierarchy (joined and single
498 table inheritance only). Valid values are:
500 * "'inline'" - specifies this class should be part of
501 the "with_polymorphic" mappers, e.g. its columns will be included
502 in a SELECT query against the base.
504 * "'selectin'" - specifies that when instances of this class
505 are loaded, an additional SELECT will be emitted to retrieve
506 the columns specific to this subclass. The SELECT uses
507 IN to fetch multiple subclasses at once.
509 .. seealso::
511 :ref:`with_polymorphic_mapper_config`
513 :ref:`polymorphic_selectin`
515 :param polymorphic_on: Specifies the column, attribute, or
516 SQL expression used to determine the target class for an
517 incoming row, when inheriting classes are present.
519 May be specified as a string attribute name, or as a SQL
520 expression such as a :class:`_schema.Column` or in a Declarative
521 mapping a :func:`_orm.mapped_column` object. It is typically
522 expected that the SQL expression corresponds to a column in the
523 base-most mapped :class:`.Table`::
525 class Employee(Base):
526 __tablename__ = "employee"
528 id: Mapped[int] = mapped_column(primary_key=True)
529 discriminator: Mapped[str] = mapped_column(String(50))
531 __mapper_args__ = {
532 "polymorphic_on": discriminator,
533 "polymorphic_identity": "employee",
534 }
536 It may also be specified
537 as a SQL expression, as in this example where we
538 use the :func:`.case` construct to provide a conditional
539 approach::
541 class Employee(Base):
542 __tablename__ = "employee"
544 id: Mapped[int] = mapped_column(primary_key=True)
545 discriminator: Mapped[str] = mapped_column(String(50))
547 __mapper_args__ = {
548 "polymorphic_on": case(
549 (discriminator == "EN", "engineer"),
550 (discriminator == "MA", "manager"),
551 else_="employee",
552 ),
553 "polymorphic_identity": "employee",
554 }
556 It may also refer to any attribute using its string name,
557 which is of particular use when using annotated column
558 configurations::
560 class Employee(Base):
561 __tablename__ = "employee"
563 id: Mapped[int] = mapped_column(primary_key=True)
564 discriminator: Mapped[str]
566 __mapper_args__ = {
567 "polymorphic_on": "discriminator",
568 "polymorphic_identity": "employee",
569 }
571 When setting ``polymorphic_on`` to reference an
572 attribute or expression that's not present in the
573 locally mapped :class:`_schema.Table`, yet the value
574 of the discriminator should be persisted to the database,
575 the value of the
576 discriminator is not automatically set on new
577 instances; this must be handled by the user,
578 either through manual means or via event listeners.
579 A typical approach to establishing such a listener
580 looks like::
582 from sqlalchemy import event
583 from sqlalchemy.orm import object_mapper
586 @event.listens_for(Employee, "init", propagate=True)
587 def set_identity(instance, *arg, **kw):
588 mapper = object_mapper(instance)
589 instance.discriminator = mapper.polymorphic_identity
591 Where above, we assign the value of ``polymorphic_identity``
592 for the mapped class to the ``discriminator`` attribute,
593 thus persisting the value to the ``discriminator`` column
594 in the database.
596 .. warning::
598 Currently, **only one discriminator column may be set**, typically
599 on the base-most class in the hierarchy. "Cascading" polymorphic
600 columns are not yet supported.
602 .. seealso::
604 :ref:`inheritance_toplevel`
606 :param polymorphic_identity: Specifies the value which
607 identifies this particular class as returned by the column expression
608 referred to by the :paramref:`_orm.Mapper.polymorphic_on` setting. As
609 rows are received, the value corresponding to the
610 :paramref:`_orm.Mapper.polymorphic_on` column expression is compared
611 to this value, indicating which subclass should be used for the newly
612 reconstructed object.
614 .. seealso::
616 :ref:`inheritance_toplevel`
618 :param properties: A dictionary mapping the string names of object
619 attributes to :class:`.MapperProperty` instances, which define the
620 persistence behavior of that attribute. Note that
621 :class:`_schema.Column`
622 objects present in
623 the mapped :class:`_schema.Table` are automatically placed into
624 ``ColumnProperty`` instances upon mapping, unless overridden.
625 When using Declarative, this argument is passed automatically,
626 based on all those :class:`.MapperProperty` instances declared
627 in the declared class body.
629 .. seealso::
631 :ref:`orm_mapping_properties` - in the
632 :ref:`orm_mapping_classes_toplevel`
634 :param primary_key: A list of :class:`_schema.Column`
635 objects, or alternatively string names of attribute names which
636 refer to :class:`_schema.Column`, which define
637 the primary key to be used against this mapper's selectable unit.
638 This is normally simply the primary key of the ``local_table``, but
639 can be overridden here.
641 .. versionchanged:: 2.0.2 :paramref:`_orm.Mapper.primary_key`
642 arguments may be indicated as string attribute names as well.
644 .. seealso::
646 :ref:`mapper_primary_key` - background and example use
648 :param version_id_col: A :class:`_schema.Column`
649 that will be used to keep a running version id of rows
650 in the table. This is used to detect concurrent updates or
651 the presence of stale data in a flush. The methodology is to
652 detect if an UPDATE statement does not match the last known
653 version id, a
654 :class:`~sqlalchemy.orm.exc.StaleDataError` exception is
655 thrown.
656 By default, the column must be of :class:`.Integer` type,
657 unless ``version_id_generator`` specifies an alternative version
658 generator.
660 .. seealso::
662 :ref:`mapper_version_counter` - discussion of version counting
663 and rationale.
665 :param version_id_generator: Define how new version ids should
666 be generated. Defaults to ``None``, which indicates that
667 a simple integer counting scheme be employed. To provide a custom
668 versioning scheme, provide a callable function of the form::
670 def generate_version(version):
671 return next_version
673 Alternatively, server-side versioning functions such as triggers,
674 or programmatic versioning schemes outside of the version id
675 generator may be used, by specifying the value ``False``.
676 Please see :ref:`server_side_version_counter` for a discussion
677 of important points when using this option.
679 .. seealso::
681 :ref:`custom_version_counter`
683 :ref:`server_side_version_counter`
686 :param with_polymorphic: A tuple in the form ``(<classes>,
687 <selectable>)`` indicating the default style of "polymorphic"
688 loading, that is, which tables are queried at once. <classes> is
689 any single or list of mappers and/or classes indicating the
690 inherited classes that should be loaded at once. The special value
691 ``'*'`` may be used to indicate all descending classes should be
692 loaded immediately. The second tuple argument <selectable>
693 indicates a selectable that will be used to query for multiple
694 classes.
696 The :paramref:`_orm.Mapper.polymorphic_load` parameter may be
697 preferable over the use of :paramref:`_orm.Mapper.with_polymorphic`
698 in modern mappings to indicate a per-subclass technique of
699 indicating polymorphic loading styles.
701 .. seealso::
703 :ref:`with_polymorphic_mapper_config`
705 """
706 self.class_ = util.assert_arg_type(class_, type, "class_")
707 self._sort_key = "%s.%s" % (
708 self.class_.__module__,
709 self.class_.__name__,
710 )
712 self._primary_key_argument = util.to_list(primary_key)
714 self.always_refresh = always_refresh
716 if isinstance(version_id_col, MapperProperty):
717 self.version_id_prop = version_id_col
718 self.version_id_col = None
719 else:
720 self.version_id_col = (
721 coercions.expect(
722 roles.ColumnArgumentOrKeyRole,
723 version_id_col,
724 argname="version_id_col",
725 )
726 if version_id_col is not None
727 else None
728 )
730 if version_id_generator is False:
731 self.version_id_generator = False
732 elif version_id_generator is None:
733 self.version_id_generator = lambda x: (x or 0) + 1
734 else:
735 self.version_id_generator = version_id_generator
737 self.concrete = concrete
738 self.single = False
740 if inherits is not None:
741 self.inherits = _parse_mapper_argument(inherits)
742 else:
743 self.inherits = None
745 if local_table is not None:
746 self.local_table = coercions.expect(
747 roles.FromClauseRole,
748 local_table,
749 disable_inspection=True,
750 argname="local_table",
751 )
752 elif self.inherits:
753 # note this is a new flow as of 2.0 so that
754 # .local_table need not be Optional
755 self.local_table = self.inherits.local_table
756 self.single = True
757 else:
758 raise sa_exc.ArgumentError(
759 f"Mapper[{self.class_.__name__}(None)] has None for a "
760 "primary table argument and does not specify 'inherits'"
761 )
763 if inherit_condition is not None:
764 self.inherit_condition = coercions.expect(
765 roles.OnClauseRole, inherit_condition
766 )
767 else:
768 self.inherit_condition = None
770 self.inherit_foreign_keys = inherit_foreign_keys
771 self._init_properties = dict(properties) if properties else {}
772 self._delete_orphans = []
773 self.batch = batch
774 self.eager_defaults = eager_defaults
775 self.column_prefix = column_prefix
777 # interim - polymorphic_on is further refined in
778 # _configure_polymorphic_setter
779 self.polymorphic_on = (
780 coercions.expect( # type: ignore
781 roles.ColumnArgumentOrKeyRole,
782 polymorphic_on,
783 argname="polymorphic_on",
784 )
785 if polymorphic_on is not None
786 else None
787 )
788 self.polymorphic_abstract = polymorphic_abstract
789 self._dependency_processors = []
790 self.validators = util.EMPTY_DICT
791 self.passive_updates = passive_updates
792 self.passive_deletes = passive_deletes
793 self.legacy_is_orphan = legacy_is_orphan
794 self._clause_adapter = None
795 self._requires_row_aliasing = False
796 self._inherits_equated_pairs = None
797 self._memoized_values = {}
798 self._compiled_cache_size = _compiled_cache_size
799 self._reconstructor = None
800 self.allow_partial_pks = allow_partial_pks
802 if self.inherits and not self.concrete:
803 self.confirm_deleted_rows = False
804 else:
805 self.confirm_deleted_rows = confirm_deleted_rows
807 self._set_with_polymorphic(with_polymorphic)
808 self.polymorphic_load = polymorphic_load
810 # our 'polymorphic identity', a string name that when located in a
811 # result set row indicates this Mapper should be used to construct
812 # the object instance for that row.
813 self.polymorphic_identity = polymorphic_identity
815 # a dictionary of 'polymorphic identity' names, associating those
816 # names with Mappers that will be used to construct object instances
817 # upon a select operation.
818 if _polymorphic_map is None:
819 self.polymorphic_map = {}
820 else:
821 self.polymorphic_map = _polymorphic_map
823 if include_properties is not None:
824 self.include_properties = util.to_set(include_properties)
825 else:
826 self.include_properties = None
827 if exclude_properties:
828 self.exclude_properties = util.to_set(exclude_properties)
829 else:
830 self.exclude_properties = None
832 # prevent this mapper from being constructed
833 # while a configure_mappers() is occurring (and defer a
834 # configure_mappers() until construction succeeds)
835 with _CONFIGURE_MUTEX:
836 cast("MapperEvents", self.dispatch._events)._new_mapper_instance(
837 class_, self
838 )
839 self._configure_inheritance()
840 self._configure_class_instrumentation()
841 self._configure_properties()
842 self._configure_polymorphic_setter()
843 self._configure_pks()
844 self.registry._flag_new_mapper(self)
845 self._log("constructed")
846 self._expire_memoizations()
848 self.dispatch.after_mapper_constructed(self, self.class_)
850 def _prefer_eager_defaults(self, dialect, table):
851 if self.eager_defaults == "auto":
852 if not table.implicit_returning:
853 return False
855 return (
856 table in self._server_default_col_keys
857 and dialect.insert_executemany_returning
858 )
859 else:
860 return self.eager_defaults
862 def _gen_cache_key(self, anon_map, bindparams):
863 return (self,)
865 # ### BEGIN
866 # ATTRIBUTE DECLARATIONS START HERE
868 is_mapper = True
869 """Part of the inspection API."""
871 represents_outer_join = False
873 registry: _RegistryType
875 @property
876 def mapper(self) -> Mapper[_O]:
877 """Part of the inspection API.
879 Returns self.
881 """
882 return self
884 @property
885 def entity(self):
886 r"""Part of the inspection API.
888 Returns self.class\_.
890 """
891 return self.class_
893 class_: Type[_O]
894 """The class to which this :class:`_orm.Mapper` is mapped."""
896 _identity_class: Type[_O]
898 _delete_orphans: List[Tuple[str, Type[Any]]]
899 _dependency_processors: List[_DependencyProcessor]
900 _memoized_values: Dict[Any, Callable[[], Any]]
901 _inheriting_mappers: util.WeakSequence[Mapper[Any]]
902 _all_tables: Set[TableClause]
903 _polymorphic_attr_key: Optional[str]
905 _pks_by_table: Dict[FromClause, OrderedSet[ColumnClause[Any]]]
906 _cols_by_table: Dict[FromClause, OrderedSet[ColumnElement[Any]]]
908 _props: util.OrderedDict[str, MapperProperty[Any]]
909 _init_properties: Dict[str, MapperProperty[Any]]
911 _columntoproperty: _ColumnMapping
913 _set_polymorphic_identity: Optional[Callable[[InstanceState[_O]], None]]
914 _validate_polymorphic_identity: Optional[
915 Callable[[Mapper[_O], InstanceState[_O], _InstanceDict], None]
916 ]
918 tables: Sequence[TableClause]
919 """A sequence containing the collection of :class:`_schema.Table`
920 or :class:`_schema.TableClause` objects which this :class:`_orm.Mapper`
921 is aware of.
923 If the mapper is mapped to a :class:`_expression.Join`, or an
924 :class:`_expression.Alias`
925 representing a :class:`_expression.Select`, the individual
926 :class:`_schema.Table`
927 objects that comprise the full construct will be represented here.
929 This is a *read only* attribute determined during mapper construction.
930 Behavior is undefined if directly modified.
932 """
934 validators: util.immutabledict[str, Tuple[str, Dict[str, Any]]]
935 """An immutable dictionary of attributes which have been decorated
936 using the :func:`_orm.validates` decorator.
938 The dictionary contains string attribute names as keys
939 mapped to the actual validation method.
941 """
943 always_refresh: bool
944 allow_partial_pks: bool
945 version_id_col: Optional[ColumnElement[Any]]
947 with_polymorphic: Optional[
948 Tuple[
949 Union[Literal["*"], Sequence[Union[Mapper[Any], Type[Any]]]],
950 Optional[FromClause],
951 ]
952 ]
954 version_id_generator: Optional[Union[Literal[False], Callable[[Any], Any]]]
956 local_table: FromClause
957 """The immediate :class:`_expression.FromClause` to which this
958 :class:`_orm.Mapper` refers.
960 Typically is an instance of :class:`_schema.Table`, may be any
961 :class:`.FromClause`.
963 The "local" table is the
964 selectable that the :class:`_orm.Mapper` is directly responsible for
965 managing from an attribute access and flush perspective. For
966 non-inheriting mappers, :attr:`.Mapper.local_table` will be the same
967 as :attr:`.Mapper.persist_selectable`. For inheriting mappers,
968 :attr:`.Mapper.local_table` refers to the specific portion of
969 :attr:`.Mapper.persist_selectable` that includes the columns to which
970 this :class:`.Mapper` is loading/persisting, such as a particular
971 :class:`.Table` within a join.
973 .. seealso::
975 :attr:`_orm.Mapper.persist_selectable`.
977 :attr:`_orm.Mapper.selectable`.
979 """
981 persist_selectable: FromClause
982 """The :class:`_expression.FromClause` to which this :class:`_orm.Mapper`
983 is mapped.
985 Typically is an instance of :class:`_schema.Table`, may be any
986 :class:`.FromClause`.
988 The :attr:`_orm.Mapper.persist_selectable` is similar to
989 :attr:`.Mapper.local_table`, but represents the :class:`.FromClause` that
990 represents the inheriting class hierarchy overall in an inheritance
991 scenario.
993 :attr.`.Mapper.persist_selectable` is also separate from the
994 :attr:`.Mapper.selectable` attribute, the latter of which may be an
995 alternate subquery used for selecting columns.
996 :attr.`.Mapper.persist_selectable` is oriented towards columns that
997 will be written on a persist operation.
999 .. seealso::
1001 :attr:`_orm.Mapper.selectable`.
1003 :attr:`_orm.Mapper.local_table`.
1005 """
1007 inherits: Optional[Mapper[Any]]
1008 """References the :class:`_orm.Mapper` which this :class:`_orm.Mapper`
1009 inherits from, if any.
1011 """
1013 inherit_condition: Optional[ColumnElement[bool]]
1015 configured: bool = False
1016 """Represent ``True`` if this :class:`_orm.Mapper` has been configured.
1018 This is a *read only* attribute determined during mapper construction.
1019 Behavior is undefined if directly modified.
1021 .. seealso::
1023 :func:`.configure_mappers`.
1025 """
1027 concrete: bool
1028 """Represent ``True`` if this :class:`_orm.Mapper` is a concrete
1029 inheritance mapper.
1031 This is a *read only* attribute determined during mapper construction.
1032 Behavior is undefined if directly modified.
1034 """
1036 primary_key: Tuple[ColumnElement[Any], ...]
1037 """An iterable containing the collection of :class:`_schema.Column`
1038 objects
1039 which comprise the 'primary key' of the mapped table, from the
1040 perspective of this :class:`_orm.Mapper`.
1042 This list is against the selectable in
1043 :attr:`_orm.Mapper.persist_selectable`.
1044 In the case of inheriting mappers, some columns may be managed by a
1045 superclass mapper. For example, in the case of a
1046 :class:`_expression.Join`, the
1047 primary key is determined by all of the primary key columns across all
1048 tables referenced by the :class:`_expression.Join`.
1050 The list is also not necessarily the same as the primary key column
1051 collection associated with the underlying tables; the :class:`_orm.Mapper`
1052 features a ``primary_key`` argument that can override what the
1053 :class:`_orm.Mapper` considers as primary key columns.
1055 This is a *read only* attribute determined during mapper construction.
1056 Behavior is undefined if directly modified.
1058 """
1060 class_manager: ClassManager[_O]
1061 """The :class:`.ClassManager` which maintains event listeners
1062 and class-bound descriptors for this :class:`_orm.Mapper`.
1064 This is a *read only* attribute determined during mapper construction.
1065 Behavior is undefined if directly modified.
1067 """
1069 single: bool
1070 """Represent ``True`` if this :class:`_orm.Mapper` is a single table
1071 inheritance mapper.
1073 :attr:`_orm.Mapper.local_table` will be ``None`` if this flag is set.
1075 This is a *read only* attribute determined during mapper construction.
1076 Behavior is undefined if directly modified.
1078 """
1080 polymorphic_on: Optional[KeyedColumnElement[Any]]
1081 """The :class:`_schema.Column` or SQL expression specified as the
1082 ``polymorphic_on`` argument
1083 for this :class:`_orm.Mapper`, within an inheritance scenario.
1085 This attribute is normally a :class:`_schema.Column` instance but
1086 may also be an expression, such as one derived from
1087 :func:`.cast`.
1089 This is a *read only* attribute determined during mapper construction.
1090 Behavior is undefined if directly modified.
1092 """
1094 polymorphic_map: Dict[Any, Mapper[Any]]
1095 """A mapping of "polymorphic identity" identifiers mapped to
1096 :class:`_orm.Mapper` instances, within an inheritance scenario.
1098 The identifiers can be of any type which is comparable to the
1099 type of column represented by :attr:`_orm.Mapper.polymorphic_on`.
1101 An inheritance chain of mappers will all reference the same
1102 polymorphic map object. The object is used to correlate incoming
1103 result rows to target mappers.
1105 This is a *read only* attribute determined during mapper construction.
1106 Behavior is undefined if directly modified.
1108 """
1110 polymorphic_identity: Optional[Any]
1111 """Represent an identifier which is matched against the
1112 :attr:`_orm.Mapper.polymorphic_on` column during result row loading.
1114 Used only with inheritance, this object can be of any type which is
1115 comparable to the type of column represented by
1116 :attr:`_orm.Mapper.polymorphic_on`.
1118 This is a *read only* attribute determined during mapper construction.
1119 Behavior is undefined if directly modified.
1121 """
1123 base_mapper: Mapper[Any]
1124 """The base-most :class:`_orm.Mapper` in an inheritance chain.
1126 In a non-inheriting scenario, this attribute will always be this
1127 :class:`_orm.Mapper`. In an inheritance scenario, it references
1128 the :class:`_orm.Mapper` which is parent to all other :class:`_orm.Mapper`
1129 objects in the inheritance chain.
1131 This is a *read only* attribute determined during mapper construction.
1132 Behavior is undefined if directly modified.
1134 """
1136 columns: ReadOnlyColumnCollection[str, Column[Any]]
1137 """A collection of :class:`_schema.Column` or other scalar expression
1138 objects maintained by this :class:`_orm.Mapper`.
1140 The collection behaves the same as that of the ``c`` attribute on
1141 any :class:`_schema.Table` object,
1142 except that only those columns included in
1143 this mapping are present, and are keyed based on the attribute name
1144 defined in the mapping, not necessarily the ``key`` attribute of the
1145 :class:`_schema.Column` itself. Additionally, scalar expressions mapped
1146 by :func:`.column_property` are also present here.
1148 This is a *read only* attribute determined during mapper construction.
1149 Behavior is undefined if directly modified.
1151 """
1153 c: ReadOnlyColumnCollection[str, Column[Any]]
1154 """A synonym for :attr:`_orm.Mapper.columns`."""
1156 @util.memoized_property
1157 def _path_registry(self) -> _CachingEntityRegistry:
1158 return PathRegistry.per_mapper(self)
1160 def _configure_inheritance(self):
1161 """Configure settings related to inheriting and/or inherited mappers
1162 being present."""
1164 # a set of all mappers which inherit from this one.
1165 self._inheriting_mappers = util.WeakSequence()
1167 if self.inherits:
1168 if not issubclass(self.class_, self.inherits.class_):
1169 raise sa_exc.ArgumentError(
1170 "Class '%s' does not inherit from '%s'"
1171 % (self.class_.__name__, self.inherits.class_.__name__)
1172 )
1174 self.dispatch._update(self.inherits.dispatch)
1176 if self.single:
1177 self.persist_selectable = self.inherits.persist_selectable
1178 elif self.local_table is not self.inherits.local_table:
1179 if self.concrete:
1180 self.persist_selectable = self.local_table
1181 for mapper in self.iterate_to_root():
1182 if mapper.polymorphic_on is not None:
1183 mapper._requires_row_aliasing = True
1184 else:
1185 if self.inherit_condition is None:
1186 # figure out inherit condition from our table to the
1187 # immediate table of the inherited mapper, not its
1188 # full table which could pull in other stuff we don't
1189 # want (allows test/inheritance.InheritTest4 to pass)
1190 try:
1191 self.inherit_condition = sql_util.join_condition(
1192 self.inherits.local_table, self.local_table
1193 )
1194 except sa_exc.NoForeignKeysError as nfe:
1195 assert self.inherits.local_table is not None
1196 assert self.local_table is not None
1197 raise sa_exc.NoForeignKeysError(
1198 "Can't determine the inherit condition "
1199 "between inherited table '%s' and "
1200 "inheriting "
1201 "table '%s'; tables have no "
1202 "foreign key relationships established. "
1203 "Please ensure the inheriting table has "
1204 "a foreign key relationship to the "
1205 "inherited "
1206 "table, or provide an "
1207 "'on clause' using "
1208 "the 'inherit_condition' mapper argument."
1209 % (
1210 self.inherits.local_table.description,
1211 self.local_table.description,
1212 )
1213 ) from nfe
1214 except sa_exc.AmbiguousForeignKeysError as afe:
1215 assert self.inherits.local_table is not None
1216 assert self.local_table is not None
1217 raise sa_exc.AmbiguousForeignKeysError(
1218 "Can't determine the inherit condition "
1219 "between inherited table '%s' and "
1220 "inheriting "
1221 "table '%s'; tables have more than one "
1222 "foreign key relationship established. "
1223 "Please specify the 'on clause' using "
1224 "the 'inherit_condition' mapper argument."
1225 % (
1226 self.inherits.local_table.description,
1227 self.local_table.description,
1228 )
1229 ) from afe
1230 assert self.inherits.persist_selectable is not None
1231 self.persist_selectable = sql.join(
1232 self.inherits.persist_selectable,
1233 self.local_table,
1234 self.inherit_condition,
1235 )
1237 fks = util.to_set(self.inherit_foreign_keys)
1238 self._inherits_equated_pairs = sql_util.criterion_as_pairs(
1239 self.persist_selectable.onclause,
1240 consider_as_foreign_keys=fks,
1241 )
1242 else:
1243 self.persist_selectable = self.local_table
1245 if self.polymorphic_identity is None:
1246 self._identity_class = self.class_
1248 if (
1249 not self.polymorphic_abstract
1250 and self.inherits.base_mapper.polymorphic_on is not None
1251 ):
1252 util.warn(
1253 f"{self} does not indicate a 'polymorphic_identity', "
1254 "yet is part of an inheritance hierarchy that has a "
1255 f"'polymorphic_on' column of "
1256 f"'{self.inherits.base_mapper.polymorphic_on}'. "
1257 "If this is an intermediary class that should not be "
1258 "instantiated, the class may either be left unmapped, "
1259 "or may include the 'polymorphic_abstract=True' "
1260 "parameter in its Mapper arguments. To leave the "
1261 "class unmapped when using Declarative, set the "
1262 "'__abstract__ = True' attribute on the class."
1263 )
1264 elif self.concrete:
1265 self._identity_class = self.class_
1266 else:
1267 self._identity_class = self.inherits._identity_class
1269 if self.version_id_col is None:
1270 self.version_id_col = self.inherits.version_id_col
1271 self.version_id_generator = self.inherits.version_id_generator
1272 elif (
1273 self.inherits.version_id_col is not None
1274 and self.version_id_col is not self.inherits.version_id_col
1275 ):
1276 util.warn(
1277 "Inheriting version_id_col '%s' does not match inherited "
1278 "version_id_col '%s' and will not automatically populate "
1279 "the inherited versioning column. "
1280 "version_id_col should only be specified on "
1281 "the base-most mapper that includes versioning."
1282 % (
1283 self.version_id_col.description,
1284 self.inherits.version_id_col.description,
1285 )
1286 )
1288 self.polymorphic_map = self.inherits.polymorphic_map
1289 self.batch = self.inherits.batch
1290 self.inherits._inheriting_mappers.append(self)
1291 self.base_mapper = self.inherits.base_mapper
1292 self.passive_updates = self.inherits.passive_updates
1293 self.passive_deletes = (
1294 self.inherits.passive_deletes or self.passive_deletes
1295 )
1296 self._all_tables = self.inherits._all_tables
1298 if self.polymorphic_identity is not None:
1299 if self.polymorphic_identity in self.polymorphic_map:
1300 util.warn(
1301 "Reassigning polymorphic association for identity %r "
1302 "from %r to %r: Check for duplicate use of %r as "
1303 "value for polymorphic_identity."
1304 % (
1305 self.polymorphic_identity,
1306 self.polymorphic_map[self.polymorphic_identity],
1307 self,
1308 self.polymorphic_identity,
1309 )
1310 )
1311 self.polymorphic_map[self.polymorphic_identity] = self
1313 if self.polymorphic_load and self.concrete:
1314 raise sa_exc.ArgumentError(
1315 "polymorphic_load is not currently supported "
1316 "with concrete table inheritance"
1317 )
1318 if self.polymorphic_load == "inline":
1319 self.inherits._add_with_polymorphic_subclass(self)
1320 elif self.polymorphic_load == "selectin":
1321 pass
1322 elif self.polymorphic_load is not None:
1323 raise sa_exc.ArgumentError(
1324 "unknown argument for polymorphic_load: %r"
1325 % self.polymorphic_load
1326 )
1328 else:
1329 self._all_tables = set()
1330 self.base_mapper = self
1331 assert self.local_table is not None
1332 self.persist_selectable = self.local_table
1333 if self.polymorphic_identity is not None:
1334 self.polymorphic_map[self.polymorphic_identity] = self
1335 self._identity_class = self.class_
1337 if self.persist_selectable is None:
1338 raise sa_exc.ArgumentError(
1339 "Mapper '%s' does not have a persist_selectable specified."
1340 % self
1341 )
1343 def _set_with_polymorphic(
1344 self, with_polymorphic: Optional[_WithPolymorphicArg]
1345 ) -> None:
1346 if with_polymorphic == "*":
1347 self.with_polymorphic = ("*", None)
1348 elif isinstance(with_polymorphic, (tuple, list)):
1349 if isinstance(with_polymorphic[0], (str, tuple, list)):
1350 self.with_polymorphic = cast(
1351 """Tuple[
1352 Union[
1353 Literal["*"],
1354 Sequence[Union["Mapper[Any]", Type[Any]]],
1355 ],
1356 Optional["FromClause"],
1357 ]""",
1358 with_polymorphic,
1359 )
1360 else:
1361 self.with_polymorphic = (with_polymorphic, None)
1362 elif with_polymorphic is not None:
1363 raise sa_exc.ArgumentError(
1364 f"Invalid setting for with_polymorphic: {with_polymorphic!r}"
1365 )
1366 else:
1367 self.with_polymorphic = None
1369 if self.with_polymorphic and self.with_polymorphic[1] is not None:
1370 self.with_polymorphic = (
1371 self.with_polymorphic[0],
1372 coercions.expect(
1373 roles.FromClauseRole,
1374 self.with_polymorphic[1],
1375 ),
1376 )
1378 if self.configured:
1379 self._expire_memoizations()
1381 def _add_with_polymorphic_subclass(self, mapper):
1382 subcl = mapper.class_
1383 if self.with_polymorphic is None:
1384 self._set_with_polymorphic((subcl,))
1385 elif self.with_polymorphic[0] != "*":
1386 assert isinstance(self.with_polymorphic[0], tuple)
1387 self._set_with_polymorphic(
1388 (self.with_polymorphic[0] + (subcl,), self.with_polymorphic[1])
1389 )
1391 def _set_concrete_base(self, mapper):
1392 """Set the given :class:`_orm.Mapper` as the 'inherits' for this
1393 :class:`_orm.Mapper`, assuming this :class:`_orm.Mapper` is concrete
1394 and does not already have an inherits."""
1396 assert self.concrete
1397 assert not self.inherits
1398 assert isinstance(mapper, Mapper)
1399 self.inherits = mapper
1400 self.inherits.polymorphic_map.update(self.polymorphic_map)
1401 self.polymorphic_map = self.inherits.polymorphic_map
1402 for mapper in self.iterate_to_root():
1403 if mapper.polymorphic_on is not None:
1404 mapper._requires_row_aliasing = True
1405 self.batch = self.inherits.batch
1406 for mp in self.self_and_descendants:
1407 mp.base_mapper = self.inherits.base_mapper
1408 self.inherits._inheriting_mappers.append(self)
1409 self.passive_updates = self.inherits.passive_updates
1410 self._all_tables = self.inherits._all_tables
1412 for key, prop in mapper._props.items():
1413 if key not in self._props and not self._should_exclude(
1414 key, key, local=False, column=None
1415 ):
1416 self._adapt_inherited_property(key, prop, False)
1418 def _set_polymorphic_on(self, polymorphic_on):
1419 self.polymorphic_on = polymorphic_on
1420 self._configure_polymorphic_setter(True)
1422 def _configure_class_instrumentation(self):
1423 """Associate this Mapper with the
1424 given class and entity name.
1426 Subsequent calls to ``class_mapper()`` for the ``class_`` / ``entity``
1427 name combination will return this mapper. Also decorate the
1428 `__init__` method on the mapped class to include optional
1429 auto-session attachment logic.
1431 """
1433 # we expect that declarative has applied the class manager
1434 # already and set up a registry. if this is None,
1435 # this raises as of 2.0.
1436 manager = attributes.opt_manager_of_class(self.class_)
1438 if manager is None or not manager.registry:
1439 raise sa_exc.InvalidRequestError(
1440 "The _mapper() function and Mapper() constructor may not be "
1441 "invoked directly outside of a declarative registry."
1442 " Please use the sqlalchemy.orm.registry.map_imperatively() "
1443 "function for a classical mapping."
1444 )
1446 self.dispatch.instrument_class(self, self.class_)
1448 # this invokes the class_instrument event and sets up
1449 # the __init__ method. documented behavior is that this must
1450 # occur after the instrument_class event above.
1451 # yes two events with the same two words reversed and different APIs.
1452 # :(
1454 manager = instrumentation.register_class(
1455 self.class_,
1456 mapper=self,
1457 expired_attribute_loader=util.partial(
1458 loading._load_scalar_attributes, self
1459 ),
1460 # finalize flag means instrument the __init__ method
1461 # and call the class_instrument event
1462 finalize=True,
1463 )
1465 self.class_manager = manager
1467 assert manager.registry is not None
1468 self.registry = manager.registry
1470 # The remaining members can be added by any mapper,
1471 # e_name None or not.
1472 if manager.mapper is None:
1473 return
1475 event.listen(manager, "init", _event_on_init, raw=True)
1477 for key, method in util.iterate_attributes(self.class_):
1478 if key == "__init__" and hasattr(method, "_sa_original_init"):
1479 method = method._sa_original_init
1480 if hasattr(method, "__func__"):
1481 method = method.__func__
1482 if callable(method):
1483 if hasattr(method, "__sa_reconstructor__"):
1484 self._reconstructor = method
1485 event.listen(manager, "load", _event_on_load, raw=True)
1486 elif hasattr(method, "__sa_validators__"):
1487 validation_opts = method.__sa_validation_opts__
1488 for name in method.__sa_validators__:
1489 if name in self.validators:
1490 raise sa_exc.InvalidRequestError(
1491 "A validation function for mapped "
1492 "attribute %r on mapper %s already exists."
1493 % (name, self)
1494 )
1495 self.validators = self.validators.union(
1496 {name: (method, validation_opts)}
1497 )
1499 def _set_dispose_flags(self) -> None:
1500 self.configured = True
1501 self._ready_for_configure = True
1502 self._dispose_called = True
1504 self.__dict__.pop("_configure_failed", None)
1506 def _str_arg_to_mapped_col(self, argname: str, key: str) -> Column[Any]:
1507 try:
1508 prop = self._props[key]
1509 except KeyError as err:
1510 raise sa_exc.ArgumentError(
1511 f"Can't determine {argname} column '{key}' - "
1512 "no attribute is mapped to this name."
1513 ) from err
1514 try:
1515 expr = prop.expression
1516 except AttributeError as ae:
1517 raise sa_exc.ArgumentError(
1518 f"Can't determine {argname} column '{key}'; "
1519 "property does not refer to a single mapped Column"
1520 ) from ae
1521 if not isinstance(expr, Column):
1522 raise sa_exc.ArgumentError(
1523 f"Can't determine {argname} column '{key}'; "
1524 "property does not refer to a single "
1525 "mapped Column"
1526 )
1527 return expr
1529 def _configure_pks(self) -> None:
1530 self.tables = sql_util.find_tables(self.persist_selectable)
1532 self._all_tables.update(t for t in self.tables)
1534 self._pks_by_table = {}
1535 self._cols_by_table = {}
1537 all_cols = util.column_set(
1538 chain(*[col.proxy_set for col in self._columntoproperty])
1539 )
1541 pk_cols = util.column_set(c for c in all_cols if c.primary_key)
1543 # identify primary key columns which are also mapped by this mapper.
1544 for fc in set(self.tables).union([self.persist_selectable]):
1545 if fc.primary_key and pk_cols.issuperset(fc.primary_key):
1546 # ordering is important since it determines the ordering of
1547 # mapper.primary_key (and therefore query.get())
1548 self._pks_by_table[fc] = util.ordered_column_set( # type: ignore # noqa: E501
1549 fc.primary_key
1550 ).intersection(
1551 pk_cols
1552 )
1553 self._cols_by_table[fc] = util.ordered_column_set(fc.c).intersection( # type: ignore # noqa: E501
1554 all_cols
1555 )
1557 if self._primary_key_argument:
1558 coerced_pk_arg = [
1559 (
1560 self._str_arg_to_mapped_col("primary_key", c)
1561 if isinstance(c, str)
1562 else c
1563 )
1564 for c in (
1565 coercions.expect(
1566 roles.DDLConstraintColumnRole,
1567 coerce_pk,
1568 argname="primary_key",
1569 )
1570 for coerce_pk in self._primary_key_argument
1571 )
1572 ]
1573 else:
1574 coerced_pk_arg = None
1576 # if explicit PK argument sent, add those columns to the
1577 # primary key mappings
1578 if coerced_pk_arg:
1579 for k in coerced_pk_arg:
1580 if k.table not in self._pks_by_table:
1581 self._pks_by_table[k.table] = util.OrderedSet()
1582 self._pks_by_table[k.table].add(k)
1584 # otherwise, see that we got a full PK for the mapped table
1585 elif (
1586 self.persist_selectable not in self._pks_by_table
1587 or len(self._pks_by_table[self.persist_selectable]) == 0
1588 ):
1589 raise sa_exc.ArgumentError(
1590 "Mapper %s could not assemble any primary "
1591 "key columns for mapped table '%s'"
1592 % (self, self.persist_selectable.description)
1593 )
1594 elif self.local_table not in self._pks_by_table and isinstance(
1595 self.local_table, schema.Table
1596 ):
1597 util.warn(
1598 "Could not assemble any primary "
1599 "keys for locally mapped table '%s' - "
1600 "no rows will be persisted in this Table."
1601 % self.local_table.description
1602 )
1604 if (
1605 self.inherits
1606 and not self.concrete
1607 and not self._primary_key_argument
1608 ):
1609 # if inheriting, the "primary key" for this mapper is
1610 # that of the inheriting (unless concrete or explicit)
1611 self.primary_key = self.inherits.primary_key
1612 else:
1613 # determine primary key from argument or persist_selectable pks
1614 primary_key: Collection[ColumnElement[Any]]
1616 if coerced_pk_arg:
1617 primary_key = [
1618 cc if cc is not None else c
1619 for cc, c in (
1620 (self.persist_selectable.corresponding_column(c), c)
1621 for c in coerced_pk_arg
1622 )
1623 ]
1624 else:
1625 # if heuristically determined PKs, reduce to the minimal set
1626 # of columns by eliminating FK->PK pairs for a multi-table
1627 # expression. May over-reduce for some kinds of UNIONs
1628 # / CTEs; use explicit PK argument for these special cases
1629 primary_key = sql_util.reduce_columns(
1630 self._pks_by_table[self.persist_selectable],
1631 ignore_nonexistent_tables=True,
1632 )
1634 if len(primary_key) == 0:
1635 raise sa_exc.ArgumentError(
1636 "Mapper %s could not assemble any primary "
1637 "key columns for mapped table '%s'"
1638 % (self, self.persist_selectable.description)
1639 )
1641 self.primary_key = tuple(primary_key)
1642 self._log("Identified primary key columns: %s", primary_key)
1644 # determine cols that aren't expressed within our tables; mark these
1645 # as "read only" properties which are refreshed upon INSERT/UPDATE
1646 self._readonly_props = {
1647 self._columntoproperty[col]
1648 for col in self._columntoproperty
1649 if self._columntoproperty[col] not in self._identity_key_props
1650 and (
1651 not hasattr(col, "table")
1652 or col.table not in self._cols_by_table
1653 )
1654 }
1656 def _configure_properties(self) -> None:
1657 self.columns = self.c = sql_base.ColumnCollection() # type: ignore
1659 # object attribute names mapped to MapperProperty objects
1660 self._props = util.OrderedDict()
1662 # table columns mapped to MapperProperty
1663 self._columntoproperty = _ColumnMapping(self)
1665 explicit_col_props_by_column: Dict[
1666 KeyedColumnElement[Any], Tuple[str, ColumnProperty[Any]]
1667 ] = {}
1668 explicit_col_props_by_key: Dict[str, ColumnProperty[Any]] = {}
1670 # step 1: go through properties that were explicitly passed
1671 # in the properties dictionary. For Columns that are local, put them
1672 # aside in a separate collection we will reconcile with the Table
1673 # that's given. For other properties, set them up in _props now.
1674 if self._init_properties:
1675 for key, prop_arg in self._init_properties.items():
1676 if not isinstance(prop_arg, MapperProperty):
1677 possible_col_prop = self._make_prop_from_column(
1678 key, prop_arg
1679 )
1680 else:
1681 possible_col_prop = prop_arg
1683 # issue #8705. if the explicit property is actually a
1684 # Column that is local to the local Table, don't set it up
1685 # in ._props yet, integrate it into the order given within
1686 # the Table.
1688 _map_as_property_now = True
1689 if isinstance(possible_col_prop, properties.ColumnProperty):
1690 for given_col in possible_col_prop.columns:
1691 if self.local_table.c.contains_column(given_col):
1692 _map_as_property_now = False
1693 explicit_col_props_by_key[key] = possible_col_prop
1694 explicit_col_props_by_column[given_col] = (
1695 key,
1696 possible_col_prop,
1697 )
1699 if _map_as_property_now:
1700 self._configure_property(
1701 key,
1702 possible_col_prop,
1703 init=False,
1704 )
1706 # step 2: pull properties from the inherited mapper. reconcile
1707 # columns with those which are explicit above. for properties that
1708 # are only in the inheriting mapper, set them up as local props
1709 if self.inherits:
1710 for key, inherited_prop in self.inherits._props.items():
1711 if self._should_exclude(key, key, local=False, column=None):
1712 continue
1714 incoming_prop = explicit_col_props_by_key.get(key)
1715 if incoming_prop:
1716 new_prop = self._reconcile_prop_with_incoming_columns(
1717 key,
1718 inherited_prop,
1719 warn_only=False,
1720 incoming_prop=incoming_prop,
1721 )
1722 explicit_col_props_by_key[key] = new_prop
1724 for inc_col in incoming_prop.columns:
1725 explicit_col_props_by_column[inc_col] = (
1726 key,
1727 new_prop,
1728 )
1729 elif key not in self._props:
1730 self._adapt_inherited_property(key, inherited_prop, False)
1732 # step 3. Iterate through all columns in the persist selectable.
1733 # this includes not only columns in the local table / fromclause,
1734 # but also those columns in the superclass table if we are joined
1735 # inh or single inh mapper. map these columns as well. additional
1736 # reconciliation against inherited columns occurs here also.
1738 for column in self.persist_selectable.columns:
1739 if column in explicit_col_props_by_column:
1740 # column was explicitly passed to properties; configure
1741 # it now in the order in which it corresponds to the
1742 # Table / selectable
1743 key, prop = explicit_col_props_by_column[column]
1744 self._configure_property(key, prop, init=False)
1745 continue
1747 elif column in self._columntoproperty:
1748 continue
1750 column_key = (self.column_prefix or "") + column.key
1751 if self._should_exclude(
1752 column.key,
1753 column_key,
1754 local=self.local_table.c.contains_column(column),
1755 column=column,
1756 ):
1757 continue
1759 # adjust the "key" used for this column to that
1760 # of the inheriting mapper
1761 for mapper in self.iterate_to_root():
1762 if column in mapper._columntoproperty:
1763 column_key = mapper._columntoproperty[column].key
1765 self._configure_property(
1766 column_key,
1767 column,
1768 init=False,
1769 setparent=True,
1770 )
1772 def _configure_polymorphic_setter(self, init=False):
1773 """Configure an attribute on the mapper representing the
1774 'polymorphic_on' column, if applicable, and not
1775 already generated by _configure_properties (which is typical).
1777 Also create a setter function which will assign this
1778 attribute to the value of the 'polymorphic_identity'
1779 upon instance construction, also if applicable. This
1780 routine will run when an instance is created.
1782 """
1783 setter = False
1784 polymorphic_key: Optional[str] = None
1786 if self.polymorphic_on is not None:
1787 setter = True
1789 if isinstance(self.polymorphic_on, str):
1790 # polymorphic_on specified as a string - link
1791 # it to mapped ColumnProperty
1792 try:
1793 self.polymorphic_on = self._props[self.polymorphic_on]
1794 except KeyError as err:
1795 raise sa_exc.ArgumentError(
1796 "Can't determine polymorphic_on "
1797 "value '%s' - no attribute is "
1798 "mapped to this name." % self.polymorphic_on
1799 ) from err
1801 if self.polymorphic_on in self._columntoproperty:
1802 # polymorphic_on is a column that is already mapped
1803 # to a ColumnProperty
1804 prop = self._columntoproperty[self.polymorphic_on]
1805 elif isinstance(self.polymorphic_on, MapperProperty):
1806 # polymorphic_on is directly a MapperProperty,
1807 # ensure it's a ColumnProperty
1808 if not isinstance(
1809 self.polymorphic_on, properties.ColumnProperty
1810 ):
1811 raise sa_exc.ArgumentError(
1812 "Only direct column-mapped "
1813 "property or SQL expression "
1814 "can be passed for polymorphic_on"
1815 )
1816 prop = self.polymorphic_on
1817 else:
1818 # polymorphic_on is a Column or SQL expression and
1819 # doesn't appear to be mapped. this means it can be 1.
1820 # only present in the with_polymorphic selectable or
1821 # 2. a totally standalone SQL expression which we'd
1822 # hope is compatible with this mapper's persist_selectable
1823 col = self.persist_selectable.corresponding_column(
1824 self.polymorphic_on
1825 )
1826 if col is None:
1827 # polymorphic_on doesn't derive from any
1828 # column/expression isn't present in the mapped
1829 # table. we will make a "hidden" ColumnProperty
1830 # for it. Just check that if it's directly a
1831 # schema.Column and we have with_polymorphic, it's
1832 # likely a user error if the schema.Column isn't
1833 # represented somehow in either persist_selectable or
1834 # with_polymorphic. Otherwise as of 0.7.4 we
1835 # just go with it and assume the user wants it
1836 # that way (i.e. a CASE statement)
1837 setter = False
1838 instrument = False
1839 col = self.polymorphic_on
1840 if isinstance(col, schema.Column) and (
1841 self.with_polymorphic is None
1842 or self.with_polymorphic[1] is None
1843 or self.with_polymorphic[1].corresponding_column(col)
1844 is None
1845 ):
1846 raise sa_exc.InvalidRequestError(
1847 "Could not map polymorphic_on column "
1848 "'%s' to the mapped table - polymorphic "
1849 "loads will not function properly"
1850 % col.description
1851 )
1852 else:
1853 # column/expression that polymorphic_on derives from
1854 # is present in our mapped table
1855 # and is probably mapped, but polymorphic_on itself
1856 # is not. This happens when
1857 # the polymorphic_on is only directly present in the
1858 # with_polymorphic selectable, as when use
1859 # polymorphic_union.
1860 # we'll make a separate ColumnProperty for it.
1861 instrument = True
1862 key = getattr(col, "key", None)
1863 if key:
1864 if self._should_exclude(key, key, False, col):
1865 raise sa_exc.InvalidRequestError(
1866 "Cannot exclude or override the "
1867 "discriminator column %r" % key
1868 )
1869 else:
1870 self.polymorphic_on = col = col.label("_sa_polymorphic_on")
1871 key = col.key
1873 prop = properties.ColumnProperty(col, _instrument=instrument)
1874 self._configure_property(key, prop, init=init, setparent=True)
1876 # the actual polymorphic_on should be the first public-facing
1877 # column in the property
1878 self.polymorphic_on = prop.columns[0]
1879 polymorphic_key = prop.key
1880 else:
1881 # no polymorphic_on was set.
1882 # check inheriting mappers for one.
1883 for mapper in self.iterate_to_root():
1884 # determine if polymorphic_on of the parent
1885 # should be propagated here. If the col
1886 # is present in our mapped table, or if our mapped
1887 # table is the same as the parent (i.e. single table
1888 # inheritance), we can use it
1889 if mapper.polymorphic_on is not None:
1890 if self.persist_selectable is mapper.persist_selectable:
1891 self.polymorphic_on = mapper.polymorphic_on
1892 else:
1893 self.polymorphic_on = (
1894 self.persist_selectable
1895 ).corresponding_column(mapper.polymorphic_on)
1896 # we can use the parent mapper's _set_polymorphic_identity
1897 # directly; it ensures the polymorphic_identity of the
1898 # instance's mapper is used so is portable to subclasses.
1899 if self.polymorphic_on is not None:
1900 self._set_polymorphic_identity = (
1901 mapper._set_polymorphic_identity
1902 )
1903 self._polymorphic_attr_key = (
1904 mapper._polymorphic_attr_key
1905 )
1906 self._validate_polymorphic_identity = (
1907 mapper._validate_polymorphic_identity
1908 )
1909 else:
1910 self._set_polymorphic_identity = None
1911 self._polymorphic_attr_key = None
1912 return
1914 if self.polymorphic_abstract and self.polymorphic_on is None:
1915 raise sa_exc.InvalidRequestError(
1916 "The Mapper.polymorphic_abstract parameter may only be used "
1917 "on a mapper hierarchy which includes the "
1918 "Mapper.polymorphic_on parameter at the base of the hierarchy."
1919 )
1921 if setter:
1923 def _set_polymorphic_identity(state):
1924 dict_ = state.dict
1925 # TODO: what happens if polymorphic_on column attribute name
1926 # does not match .key?
1928 polymorphic_identity = (
1929 state.manager.mapper.polymorphic_identity
1930 )
1931 if (
1932 polymorphic_identity is None
1933 and state.manager.mapper.polymorphic_abstract
1934 ):
1935 raise sa_exc.InvalidRequestError(
1936 f"Can't instantiate class for {state.manager.mapper}; "
1937 "mapper is marked polymorphic_abstract=True"
1938 )
1940 state.get_impl(polymorphic_key).set(
1941 state,
1942 dict_,
1943 polymorphic_identity,
1944 None,
1945 )
1947 self._polymorphic_attr_key = polymorphic_key
1949 def _validate_polymorphic_identity(mapper, state, dict_):
1950 if (
1951 polymorphic_key in dict_
1952 and dict_[polymorphic_key]
1953 not in mapper._acceptable_polymorphic_identities
1954 ):
1955 util.warn_limited(
1956 "Flushing object %s with "
1957 "incompatible polymorphic identity %r; the "
1958 "object may not refresh and/or load correctly",
1959 (state_str(state), dict_[polymorphic_key]),
1960 )
1962 self._set_polymorphic_identity = _set_polymorphic_identity
1963 self._validate_polymorphic_identity = (
1964 _validate_polymorphic_identity
1965 )
1966 else:
1967 self._polymorphic_attr_key = None
1968 self._set_polymorphic_identity = None
1970 _validate_polymorphic_identity = None
1972 @HasMemoized.memoized_attribute
1973 def _version_id_prop(self):
1974 if self.version_id_col is not None:
1975 return self._columntoproperty[self.version_id_col]
1976 else:
1977 return None
1979 @HasMemoized.memoized_attribute
1980 def _acceptable_polymorphic_identities(self):
1981 identities = set()
1983 stack = deque([self])
1984 while stack:
1985 item = stack.popleft()
1986 if item.persist_selectable is self.persist_selectable:
1987 identities.add(item.polymorphic_identity)
1988 stack.extend(item._inheriting_mappers)
1990 return identities
1992 @HasMemoized.memoized_attribute
1993 def _prop_set(self):
1994 return frozenset(self._props.values())
1996 @util.preload_module("sqlalchemy.orm.descriptor_props")
1997 def _adapt_inherited_property(self, key, prop, init):
1998 descriptor_props = util.preloaded.orm_descriptor_props
2000 if not self.concrete:
2001 self._configure_property(key, prop, init=False, setparent=False)
2002 elif key not in self._props:
2003 # determine if the class implements this attribute; if not,
2004 # or if it is implemented by the attribute that is handling the
2005 # given superclass-mapped property, then we need to report that we
2006 # can't use this at the instance level since we are a concrete
2007 # mapper and we don't map this. don't trip user-defined
2008 # descriptors that might have side effects when invoked.
2009 implementing_attribute = self.class_manager._get_class_attr_mro(
2010 key, prop
2011 )
2012 if implementing_attribute is prop or (
2013 isinstance(
2014 implementing_attribute, attributes.InstrumentedAttribute
2015 )
2016 and implementing_attribute._parententity is prop.parent
2017 ):
2018 self._configure_property(
2019 key,
2020 descriptor_props.ConcreteInheritedProperty(),
2021 init=init,
2022 setparent=True,
2023 )
2025 @util.preload_module("sqlalchemy.orm.descriptor_props")
2026 def _configure_property(
2027 self,
2028 key: str,
2029 prop_arg: Union[KeyedColumnElement[Any], MapperProperty[Any]],
2030 *,
2031 init: bool = True,
2032 setparent: bool = True,
2033 warn_for_existing: bool = False,
2034 ) -> MapperProperty[Any]:
2035 descriptor_props = util.preloaded.orm_descriptor_props
2036 self._log(
2037 "_configure_property(%s, %s)", key, prop_arg.__class__.__name__
2038 )
2040 if not isinstance(prop_arg, MapperProperty):
2041 prop: MapperProperty[Any] = self._property_from_column(
2042 key, prop_arg
2043 )
2044 else:
2045 prop = prop_arg
2047 if isinstance(prop, properties.ColumnProperty):
2048 col = self.persist_selectable.corresponding_column(prop.columns[0])
2050 # if the column is not present in the mapped table,
2051 # test if a column has been added after the fact to the
2052 # parent table (or their parent, etc.) [ticket:1570]
2053 if col is None and self.inherits:
2054 path = [self]
2055 for m in self.inherits.iterate_to_root():
2056 col = m.local_table.corresponding_column(prop.columns[0])
2057 if col is not None:
2058 for m2 in path:
2059 m2.persist_selectable._refresh_for_new_column(col)
2060 col = self.persist_selectable.corresponding_column(
2061 prop.columns[0]
2062 )
2063 break
2064 path.append(m)
2066 # subquery expression, column not present in the mapped
2067 # selectable.
2068 if col is None:
2069 col = prop.columns[0]
2071 # column is coming in after _readonly_props was
2072 # initialized; check for 'readonly'
2073 if hasattr(self, "_readonly_props") and (
2074 not hasattr(col, "table")
2075 or col.table not in self._cols_by_table
2076 ):
2077 self._readonly_props.add(prop)
2079 else:
2080 # if column is coming in after _cols_by_table was
2081 # initialized, ensure the col is in the right set
2082 if (
2083 hasattr(self, "_cols_by_table")
2084 and col.table in self._cols_by_table
2085 and col not in self._cols_by_table[col.table]
2086 ):
2087 self._cols_by_table[col.table].add(col)
2089 # if this properties.ColumnProperty represents the "polymorphic
2090 # discriminator" column, mark it. We'll need this when rendering
2091 # columns in SELECT statements.
2092 if not hasattr(prop, "_is_polymorphic_discriminator"):
2093 prop._is_polymorphic_discriminator = (
2094 col is self.polymorphic_on
2095 or prop.columns[0] is self.polymorphic_on
2096 )
2098 if isinstance(col, expression.Label):
2099 # new in 1.4, get column property against expressions
2100 # to be addressable in subqueries
2101 col.key = col._tq_key_label = key
2103 self.columns.add(col, key)
2105 for col in prop.columns:
2106 for proxy_col in col.proxy_set:
2107 self._columntoproperty[proxy_col] = prop
2109 if getattr(prop, "key", key) != key:
2110 util.warn(
2111 f"ORM mapped property {self.class_.__name__}.{prop.key} being "
2112 "assigned to attribute "
2113 f"{key!r} is already associated with "
2114 f"attribute {prop.key!r}. The attribute will be de-associated "
2115 f"from {prop.key!r}."
2116 )
2118 prop.key = key
2120 if setparent:
2121 prop.set_parent(self, init)
2123 if key in self._props and getattr(
2124 self._props[key], "_mapped_by_synonym", False
2125 ):
2126 syn = self._props[key]._mapped_by_synonym
2127 raise sa_exc.ArgumentError(
2128 "Can't call map_column=True for synonym %r=%r, "
2129 "a ColumnProperty already exists keyed to the name "
2130 "%r for column %r" % (syn, key, key, syn)
2131 )
2133 # replacement cases
2135 # case one: prop is replacing a prop that we have mapped. this is
2136 # independent of whatever might be in the actual class dictionary
2137 if (
2138 key in self._props
2139 and not isinstance(
2140 self._props[key], descriptor_props.ConcreteInheritedProperty
2141 )
2142 and not isinstance(prop, descriptor_props.SynonymProperty)
2143 ):
2144 if warn_for_existing:
2145 util.warn_deprecated(
2146 f"User-placed attribute {self.class_.__name__}.{key} on "
2147 f"{self} is replacing an existing ORM-mapped attribute. "
2148 "Behavior is not fully defined in this case. This "
2149 "use is deprecated and will raise an error in a future "
2150 "release",
2151 "2.0",
2152 )
2153 oldprop = self._props[key]
2154 self._path_registry.pop(oldprop, None)
2156 # case two: prop is replacing an attribute on the class of some kind.
2157 # we have to be more careful here since it's normal when using
2158 # Declarative that all the "declared attributes" on the class
2159 # get replaced.
2160 elif (
2161 warn_for_existing
2162 and self.class_.__dict__.get(key, None) is not None
2163 and not isinstance(prop, descriptor_props.SynonymProperty)
2164 and not isinstance(
2165 self._props.get(key, None),
2166 descriptor_props.ConcreteInheritedProperty,
2167 )
2168 ):
2169 util.warn_deprecated(
2170 f"User-placed attribute {self.class_.__name__}.{key} on "
2171 f"{self} is replacing an existing class-bound "
2172 "attribute of the same name. "
2173 "Behavior is not fully defined in this case. This "
2174 "use is deprecated and will raise an error in a future "
2175 "release",
2176 "2.0",
2177 )
2179 self._props[key] = prop
2181 prop.instrument_class(self)
2183 for mapper in self._inheriting_mappers:
2184 mapper._adapt_inherited_property(key, prop, init)
2186 if init:
2187 prop.init()
2188 prop.post_instrument_class(self)
2190 if self.configured:
2191 self._expire_memoizations()
2193 return prop
2195 def _make_prop_from_column(
2196 self,
2197 key: str,
2198 column: Union[
2199 Sequence[KeyedColumnElement[Any]], KeyedColumnElement[Any]
2200 ],
2201 ) -> ColumnProperty[Any]:
2202 columns = util.to_list(column)
2203 mapped_column = []
2204 for c in columns:
2205 mc = self.persist_selectable.corresponding_column(c)
2206 if mc is None:
2207 mc = self.local_table.corresponding_column(c)
2208 if mc is not None:
2209 # if the column is in the local table but not the
2210 # mapped table, this corresponds to adding a
2211 # column after the fact to the local table.
2212 # [ticket:1523]
2213 self.persist_selectable._refresh_for_new_column(mc)
2214 mc = self.persist_selectable.corresponding_column(c)
2215 if mc is None:
2216 raise sa_exc.ArgumentError(
2217 "When configuring property '%s' on %s, "
2218 "column '%s' is not represented in the mapper's "
2219 "table. Use the `column_property()` function to "
2220 "force this column to be mapped as a read-only "
2221 "attribute." % (key, self, c)
2222 )
2223 mapped_column.append(mc)
2224 return properties.ColumnProperty(*mapped_column)
2226 def _reconcile_prop_with_incoming_columns(
2227 self,
2228 key: str,
2229 existing_prop: MapperProperty[Any],
2230 warn_only: bool,
2231 incoming_prop: Optional[ColumnProperty[Any]] = None,
2232 single_column: Optional[KeyedColumnElement[Any]] = None,
2233 ) -> ColumnProperty[Any]:
2234 if incoming_prop and (
2235 self.concrete
2236 or not isinstance(existing_prop, properties.ColumnProperty)
2237 ):
2238 return incoming_prop
2240 existing_column = existing_prop.columns[0]
2242 if incoming_prop and existing_column in incoming_prop.columns:
2243 return incoming_prop
2245 if incoming_prop is None:
2246 assert single_column is not None
2247 incoming_column = single_column
2248 equated_pair_key = (existing_prop.columns[0], incoming_column)
2249 else:
2250 assert single_column is None
2251 incoming_column = incoming_prop.columns[0]
2252 equated_pair_key = (incoming_column, existing_prop.columns[0])
2254 if (
2255 (
2256 not self._inherits_equated_pairs
2257 or (equated_pair_key not in self._inherits_equated_pairs)
2258 )
2259 and not existing_column.shares_lineage(incoming_column)
2260 and existing_column is not self.version_id_col
2261 and incoming_column is not self.version_id_col
2262 ):
2263 msg = (
2264 "Implicitly combining column %s with column "
2265 "%s under attribute '%s'. Please configure one "
2266 "or more attributes for these same-named columns "
2267 "explicitly."
2268 % (
2269 existing_prop.columns[-1],
2270 incoming_column,
2271 key,
2272 )
2273 )
2274 if warn_only:
2275 util.warn(msg)
2276 else:
2277 raise sa_exc.InvalidRequestError(msg)
2279 # existing properties.ColumnProperty from an inheriting
2280 # mapper. make a copy and append our column to it
2281 # breakpoint()
2282 new_prop = existing_prop.copy()
2284 new_prop.columns.insert(0, incoming_column)
2285 self._log(
2286 "inserting column to existing list "
2287 "in properties.ColumnProperty %s",
2288 key,
2289 )
2290 return new_prop # type: ignore
2292 @util.preload_module("sqlalchemy.orm.descriptor_props")
2293 def _property_from_column(
2294 self,
2295 key: str,
2296 column: KeyedColumnElement[Any],
2297 ) -> ColumnProperty[Any]:
2298 """generate/update a :class:`.ColumnProperty` given a
2299 :class:`_schema.Column` or other SQL expression object."""
2301 descriptor_props = util.preloaded.orm_descriptor_props
2303 prop = self._props.get(key)
2305 if isinstance(prop, properties.ColumnProperty):
2306 return self._reconcile_prop_with_incoming_columns(
2307 key,
2308 prop,
2309 single_column=column,
2310 warn_only=prop.parent is not self,
2311 )
2312 elif prop is None or isinstance(
2313 prop, descriptor_props.ConcreteInheritedProperty
2314 ):
2315 return self._make_prop_from_column(key, column)
2316 else:
2317 raise sa_exc.ArgumentError(
2318 "WARNING: when configuring property '%s' on %s, "
2319 "column '%s' conflicts with property '%r'. "
2320 "To resolve this, map the column to the class under a "
2321 "different name in the 'properties' dictionary. Or, "
2322 "to remove all awareness of the column entirely "
2323 "(including its availability as a foreign key), "
2324 "use the 'include_properties' or 'exclude_properties' "
2325 "mapper arguments to control specifically which table "
2326 "columns get mapped." % (key, self, column.key, prop)
2327 )
2329 @util.langhelpers.tag_method_for_warnings(
2330 "This warning originated from the `configure_mappers()` process, "
2331 "which was invoked automatically in response to a user-initiated "
2332 "operation.",
2333 sa_exc.SAWarning,
2334 )
2335 def _check_configure(self) -> None:
2336 if self.registry._new_mappers:
2337 _configure_registries({self.registry}, cascade=True)
2339 def _post_configure_properties(self) -> None:
2340 """Call the ``init()`` method on all ``MapperProperties``
2341 attached to this mapper.
2343 This is a deferred configuration step which is intended
2344 to execute once all mappers have been constructed.
2346 """
2348 self._log("_post_configure_properties() started")
2349 l = [(key, prop) for key, prop in self._props.items()]
2350 for key, prop in l:
2351 self._log("initialize prop %s", key)
2353 if prop.parent is self and not prop._configure_started:
2354 prop.init()
2356 if prop._configure_finished:
2357 prop.post_instrument_class(self)
2359 self._log("_post_configure_properties() complete")
2360 self.configured = True
2362 def add_properties(self, dict_of_properties):
2363 """Add the given dictionary of properties to this mapper,
2364 using `add_property`.
2366 """
2367 for key, value in dict_of_properties.items():
2368 self.add_property(key, value)
2370 def add_property(
2371 self, key: str, prop: Union[Column[Any], MapperProperty[Any]]
2372 ) -> None:
2373 """Add an individual MapperProperty to this mapper.
2375 If the mapper has not been configured yet, just adds the
2376 property to the initial properties dictionary sent to the
2377 constructor. If this Mapper has already been configured, then
2378 the given MapperProperty is configured immediately.
2380 """
2381 prop = self._configure_property(
2382 key, prop, init=self.configured, warn_for_existing=True
2383 )
2384 assert isinstance(prop, MapperProperty)
2385 self._init_properties[key] = prop
2387 def _expire_memoizations(self) -> None:
2388 for mapper in self.iterate_to_root():
2389 mapper._reset_memoizations()
2391 @property
2392 def _log_desc(self) -> str:
2393 return (
2394 "("
2395 + self.class_.__name__
2396 + "|"
2397 + (
2398 self.local_table is not None
2399 and self.local_table.description
2400 or str(self.local_table)
2401 )
2402 + ")"
2403 )
2405 def _log(self, msg: str, *args: Any) -> None:
2406 self.logger.info("%s " + msg, *((self._log_desc,) + args))
2408 def _log_debug(self, msg: str, *args: Any) -> None:
2409 self.logger.debug("%s " + msg, *((self._log_desc,) + args))
2411 def __repr__(self) -> str:
2412 return "<Mapper at 0x%x; %s>" % (id(self), self.class_.__name__)
2414 def __str__(self) -> str:
2415 return "Mapper[%s(%s)]" % (
2416 self.class_.__name__,
2417 (
2418 self.local_table.description
2419 if self.local_table is not None
2420 else self.persist_selectable.description
2421 ),
2422 )
2424 def _is_orphan(self, state: InstanceState[_O]) -> bool:
2425 orphan_possible = False
2426 for mapper in self.iterate_to_root():
2427 for key, cls in mapper._delete_orphans:
2428 orphan_possible = True
2430 has_parent = attributes.manager_of_class(cls).has_parent(
2431 state, key, optimistic=state.has_identity
2432 )
2434 if self.legacy_is_orphan and has_parent:
2435 return False
2436 elif not self.legacy_is_orphan and not has_parent:
2437 return True
2439 if self.legacy_is_orphan:
2440 return orphan_possible
2441 else:
2442 return False
2444 def has_property(self, key: str) -> bool:
2445 return key in self._props
2447 def get_property(
2448 self, key: str, _configure_mappers: bool = False
2449 ) -> MapperProperty[Any]:
2450 """return a MapperProperty associated with the given key."""
2452 if _configure_mappers:
2453 self._check_configure()
2455 try:
2456 return self._props[key]
2457 except KeyError as err:
2458 raise sa_exc.InvalidRequestError(
2459 f"Mapper '{self}' has no property '{key}'. If this property "
2460 "was indicated from other mappers or configure events, ensure "
2461 "registry.configure() has been called."
2462 ) from err
2464 def get_property_by_column(
2465 self, column: ColumnElement[_T]
2466 ) -> MapperProperty[_T]:
2467 """Given a :class:`_schema.Column` object, return the
2468 :class:`.MapperProperty` which maps this column."""
2470 return self._columntoproperty[column]
2472 @property
2473 def iterate_properties(self):
2474 """return an iterator of all MapperProperty objects."""
2476 return iter(self._props.values())
2478 def _mappers_from_spec(
2479 self, spec: Any, selectable: Optional[FromClause]
2480 ) -> Sequence[Mapper[Any]]:
2481 """given a with_polymorphic() argument, return the set of mappers it
2482 represents.
2484 Trims the list of mappers to just those represented within the given
2485 selectable, if present. This helps some more legacy-ish mappings.
2487 """
2488 if spec == "*":
2489 mappers = list(self.self_and_descendants)
2490 elif spec:
2491 mapper_set: Set[Mapper[Any]] = set()
2492 for m in util.to_list(spec):
2493 m = _class_to_mapper(m)
2494 if not m.isa(self):
2495 raise sa_exc.InvalidRequestError(
2496 "%r does not inherit from %r" % (m, self)
2497 )
2499 if selectable is None:
2500 mapper_set.update(m.iterate_to_root())
2501 else:
2502 mapper_set.add(m)
2503 mappers = [m for m in self.self_and_descendants if m in mapper_set]
2504 else:
2505 mappers = []
2507 if selectable is not None:
2508 tables = set(
2509 sql_util.find_tables(selectable, include_aliases=True)
2510 )
2511 mappers = [m for m in mappers if m.local_table in tables]
2512 return mappers
2514 def _selectable_from_mappers(
2515 self, mappers: Iterable[Mapper[Any]], innerjoin: bool
2516 ) -> FromClause:
2517 """given a list of mappers (assumed to be within this mapper's
2518 inheritance hierarchy), construct an outerjoin amongst those mapper's
2519 mapped tables.
2521 """
2522 from_obj = self.persist_selectable
2523 for m in mappers:
2524 if m is self:
2525 continue
2526 if m.concrete:
2527 raise sa_exc.InvalidRequestError(
2528 "'with_polymorphic()' requires 'selectable' argument "
2529 "when concrete-inheriting mappers are used."
2530 )
2531 elif not m.single:
2532 if innerjoin:
2533 from_obj = from_obj.join(
2534 m.local_table, m.inherit_condition
2535 )
2536 else:
2537 from_obj = from_obj.outerjoin(
2538 m.local_table, m.inherit_condition
2539 )
2541 return from_obj
2543 @HasMemoized.memoized_attribute
2544 def _version_id_has_server_side_value(self) -> bool:
2545 vid_col = self.version_id_col
2547 if vid_col is None:
2548 return False
2550 elif not isinstance(vid_col, Column):
2551 return True
2552 else:
2553 return vid_col.server_default is not None or (
2554 vid_col.default is not None
2555 and (
2556 not vid_col.default.is_scalar
2557 and not vid_col.default.is_callable
2558 )
2559 )
2561 @HasMemoized.memoized_attribute
2562 def _single_table_criteria_component(self):
2563 if self.single and self.inherits and self.polymorphic_on is not None:
2565 hierarchy = tuple(
2566 m.polymorphic_identity
2567 for m in self.self_and_descendants
2568 if not m.polymorphic_abstract
2569 )
2571 return (
2572 self.polymorphic_on._annotate(
2573 {"parententity": self, "parentmapper": self}
2574 ),
2575 hierarchy,
2576 )
2577 else:
2578 return None
2580 @HasMemoized.memoized_attribute
2581 def _single_table_criterion(self):
2582 component = self._single_table_criteria_component
2583 if component is not None:
2584 return component[0].in_(component[1])
2585 else:
2586 return None
2588 @HasMemoized.memoized_attribute
2589 def _has_aliased_polymorphic_fromclause(self):
2590 """return True if with_polymorphic[1] is an aliased fromclause,
2591 like a subquery.
2593 As of #8168, polymorphic adaption with ORMAdapter is used only
2594 if this is present.
2596 """
2597 return self.with_polymorphic and isinstance(
2598 self.with_polymorphic[1],
2599 expression.AliasedReturnsRows,
2600 )
2602 @HasMemoized.memoized_attribute
2603 def _should_select_with_poly_adapter(self):
2604 """determine if _MapperEntity or _ORMColumnEntity will need to use
2605 polymorphic adaption when setting up a SELECT as well as fetching
2606 rows for mapped classes and subclasses against this Mapper.
2608 moved here from context.py for #8456 to generalize the ruleset
2609 for this condition.
2611 """
2613 # this has been simplified as of #8456.
2614 # rule is: if we have a with_polymorphic or a concrete-style
2615 # polymorphic selectable, *or* if the base mapper has either of those,
2616 # we turn on the adaption thing. if not, we do *no* adaption.
2617 #
2618 # (UPDATE for #8168: the above comment was not accurate, as we were
2619 # still saying "do polymorphic" if we were using an auto-generated
2620 # flattened JOIN for with_polymorphic.)
2621 #
2622 # this splits the behavior among the "regular" joined inheritance
2623 # and single inheritance mappers, vs. the "weird / difficult"
2624 # concrete and joined inh mappings that use a with_polymorphic of
2625 # some kind or polymorphic_union.
2626 #
2627 # note we have some tests in test_polymorphic_rel that query against
2628 # a subclass, then refer to the superclass that has a with_polymorphic
2629 # on it (such as test_join_from_polymorphic_explicit_aliased_three).
2630 # these tests actually adapt the polymorphic selectable (like, the
2631 # UNION or the SELECT subquery with JOIN in it) to be just the simple
2632 # subclass table. Hence even if we are a "plain" inheriting mapper
2633 # but our base has a wpoly on it, we turn on adaption. This is a
2634 # legacy case we should probably disable.
2635 #
2636 #
2637 # UPDATE: simplified way more as of #8168. polymorphic adaption
2638 # is turned off even if with_polymorphic is set, as long as there
2639 # is no user-defined aliased selectable / subquery configured.
2640 # this scales back the use of polymorphic adaption in practice
2641 # to basically no cases except for concrete inheritance with a
2642 # polymorphic base class.
2643 #
2644 return (
2645 self._has_aliased_polymorphic_fromclause
2646 or self._requires_row_aliasing
2647 or (self.base_mapper._has_aliased_polymorphic_fromclause)
2648 or self.base_mapper._requires_row_aliasing
2649 )
2651 @HasMemoized.memoized_attribute
2652 def _with_polymorphic_mappers(self) -> Sequence[Mapper[Any]]:
2653 self._check_configure()
2655 if not self.with_polymorphic:
2656 return []
2657 return self._mappers_from_spec(*self.with_polymorphic)
2659 @HasMemoized.memoized_attribute
2660 def _post_inspect(self):
2661 """This hook is invoked by attribute inspection.
2663 E.g. when Query calls:
2665 coercions.expect(roles.ColumnsClauseRole, ent, keep_inspect=True)
2667 This allows the inspection process run a configure mappers hook.
2669 """
2670 self._check_configure()
2672 @HasMemoized_ro_memoized_attribute
2673 def _with_polymorphic_selectable(self) -> FromClause:
2674 if not self.with_polymorphic:
2675 return self.persist_selectable
2677 spec, selectable = self.with_polymorphic
2678 if selectable is not None:
2679 return selectable
2680 else:
2681 return self._selectable_from_mappers(
2682 self._mappers_from_spec(spec, selectable), False
2683 )
2685 with_polymorphic_mappers = _with_polymorphic_mappers
2686 """The list of :class:`_orm.Mapper` objects included in the
2687 default "polymorphic" query.
2689 """
2691 @HasMemoized_ro_memoized_attribute
2692 def _insert_cols_evaluating_none(self):
2693 return {
2694 table: frozenset(
2695 col for col in columns if col.type.should_evaluate_none
2696 )
2697 for table, columns in self._cols_by_table.items()
2698 }
2700 @HasMemoized.memoized_attribute
2701 def _insert_cols_as_none(self):
2702 return {
2703 table: frozenset(
2704 col.key
2705 for col in columns
2706 if not col.primary_key
2707 and not col.server_default
2708 and not col.default
2709 and not col.type.should_evaluate_none
2710 )
2711 for table, columns in self._cols_by_table.items()
2712 }
2714 @HasMemoized.memoized_attribute
2715 def _propkey_to_col(self):
2716 return {
2717 table: {self._columntoproperty[col].key: col for col in columns}
2718 for table, columns in self._cols_by_table.items()
2719 }
2721 @HasMemoized.memoized_attribute
2722 def _pk_keys_by_table(self):
2723 return {
2724 table: frozenset([col.key for col in pks])
2725 for table, pks in self._pks_by_table.items()
2726 }
2728 @HasMemoized.memoized_attribute
2729 def _pk_attr_keys_by_table(self):
2730 return {
2731 table: frozenset([self._columntoproperty[col].key for col in pks])
2732 for table, pks in self._pks_by_table.items()
2733 }
2735 @HasMemoized.memoized_attribute
2736 def _server_default_cols(
2737 self,
2738 ) -> Mapping[FromClause, FrozenSet[Column[Any]]]:
2739 return {
2740 table: frozenset(
2741 [
2742 col
2743 for col in cast("Iterable[Column[Any]]", columns)
2744 if col.server_default is not None
2745 or (
2746 col.default is not None
2747 and col.default.is_clause_element
2748 )
2749 ]
2750 )
2751 for table, columns in self._cols_by_table.items()
2752 }
2754 @HasMemoized.memoized_attribute
2755 def _server_onupdate_default_cols(
2756 self,
2757 ) -> Mapping[FromClause, FrozenSet[Column[Any]]]:
2758 return {
2759 table: frozenset(
2760 [
2761 col
2762 for col in cast("Iterable[Column[Any]]", columns)
2763 if col.server_onupdate is not None
2764 or (
2765 col.onupdate is not None
2766 and col.onupdate.is_clause_element
2767 )
2768 ]
2769 )
2770 for table, columns in self._cols_by_table.items()
2771 }
2773 @HasMemoized.memoized_attribute
2774 def _server_default_col_keys(self) -> Mapping[FromClause, FrozenSet[str]]:
2775 return {
2776 table: frozenset(col.key for col in cols if col.key is not None)
2777 for table, cols in self._server_default_cols.items()
2778 }
2780 @HasMemoized.memoized_attribute
2781 def _server_onupdate_default_col_keys(
2782 self,
2783 ) -> Mapping[FromClause, FrozenSet[str]]:
2784 return {
2785 table: frozenset(col.key for col in cols if col.key is not None)
2786 for table, cols in self._server_onupdate_default_cols.items()
2787 }
2789 @HasMemoized.memoized_attribute
2790 def _server_default_plus_onupdate_propkeys(self) -> Set[str]:
2791 result: Set[str] = set()
2793 col_to_property = self._columntoproperty
2794 for table, columns in self._server_default_cols.items():
2795 result.update(
2796 col_to_property[col].key
2797 for col in columns.intersection(col_to_property)
2798 )
2799 for table, columns in self._server_onupdate_default_cols.items():
2800 result.update(
2801 col_to_property[col].key
2802 for col in columns.intersection(col_to_property)
2803 )
2804 return result
2806 @HasMemoized.memoized_instancemethod
2807 def __clause_element__(self):
2808 annotations: Dict[str, Any] = {
2809 "entity_namespace": self,
2810 "parententity": self,
2811 "parentmapper": self,
2812 }
2813 if self.persist_selectable is not self.local_table:
2814 # joined table inheritance, with polymorphic selectable,
2815 # etc.
2816 annotations["dml_table"] = self.local_table._annotate(
2817 {
2818 "entity_namespace": self,
2819 "parententity": self,
2820 "parentmapper": self,
2821 }
2822 )._set_propagate_attrs(
2823 {"compile_state_plugin": "orm", "plugin_subject": self}
2824 )
2826 return self.selectable._annotate(annotations)._set_propagate_attrs(
2827 {"compile_state_plugin": "orm", "plugin_subject": self}
2828 )
2830 @util.memoized_property
2831 def select_identity_token(self):
2832 return (
2833 expression.null()
2834 ._annotate(
2835 {
2836 "entity_namespace": self,
2837 "parententity": self,
2838 "parentmapper": self,
2839 "identity_token": True,
2840 }
2841 )
2842 ._set_propagate_attrs(
2843 {"compile_state_plugin": "orm", "plugin_subject": self}
2844 )
2845 )
2847 @property
2848 def selectable(self) -> FromClause:
2849 """The :class:`_schema.FromClause` construct this
2850 :class:`_orm.Mapper` selects from by default.
2852 Normally, this is equivalent to :attr:`.persist_selectable`, unless
2853 the ``with_polymorphic`` feature is in use, in which case the
2854 full "polymorphic" selectable is returned.
2856 """
2857 return self._with_polymorphic_selectable
2859 def _with_polymorphic_args(
2860 self,
2861 spec: Any = None,
2862 selectable: Union[Literal[False, None], FromClause] = False,
2863 innerjoin: bool = False,
2864 ) -> Tuple[Sequence[Mapper[Any]], FromClause]:
2865 if selectable not in (None, False):
2866 selectable = coercions.expect(
2867 roles.FromClauseRole,
2868 selectable,
2869 )
2871 if self.with_polymorphic:
2872 if not spec:
2873 spec = self.with_polymorphic[0]
2874 if selectable is False:
2875 selectable = self.with_polymorphic[1]
2876 elif selectable is False:
2877 selectable = None
2878 mappers = self._mappers_from_spec(spec, selectable)
2879 if selectable is not None:
2880 return mappers, selectable
2881 else:
2882 return mappers, self._selectable_from_mappers(mappers, innerjoin)
2884 @HasMemoized.memoized_attribute
2885 def _polymorphic_properties(self):
2886 return list(
2887 self._iterate_polymorphic_properties(
2888 self._with_polymorphic_mappers
2889 )
2890 )
2892 @property
2893 def _all_column_expressions(self):
2894 poly_properties = self._polymorphic_properties
2895 adapter = self._polymorphic_adapter
2897 return [
2898 adapter.columns[c] if adapter else c
2899 for prop in poly_properties
2900 if isinstance(prop, properties.ColumnProperty)
2901 and prop._renders_in_subqueries
2902 for c in prop.columns
2903 ]
2905 def _columns_plus_keys(self, polymorphic_mappers=()):
2906 if polymorphic_mappers:
2907 poly_properties = self._iterate_polymorphic_properties(
2908 polymorphic_mappers
2909 )
2910 else:
2911 poly_properties = self._polymorphic_properties
2913 return [
2914 (prop.key, prop.columns[0])
2915 for prop in poly_properties
2916 if isinstance(prop, properties.ColumnProperty)
2917 ]
2919 @HasMemoized.memoized_attribute
2920 def _polymorphic_adapter(self) -> Optional[orm_util.ORMAdapter]:
2921 if self._has_aliased_polymorphic_fromclause:
2922 return orm_util.ORMAdapter(
2923 orm_util._TraceAdaptRole.MAPPER_POLYMORPHIC_ADAPTER,
2924 self,
2925 selectable=self.selectable,
2926 equivalents=self._equivalent_columns,
2927 limit_on_entity=False,
2928 )
2929 else:
2930 return None
2932 def _iterate_polymorphic_properties(self, mappers=None):
2933 """Return an iterator of MapperProperty objects which will render into
2934 a SELECT."""
2935 if mappers is None:
2936 mappers = self._with_polymorphic_mappers
2938 if not mappers:
2939 for c in self.iterate_properties:
2940 yield c
2941 else:
2942 # in the polymorphic case, filter out discriminator columns
2943 # from other mappers, as these are sometimes dependent on that
2944 # mapper's polymorphic selectable (which we don't want rendered)
2945 for c in util.unique_list(
2946 chain(
2947 *[
2948 list(mapper.iterate_properties)
2949 for mapper in [self] + mappers
2950 ]
2951 )
2952 ):
2953 if getattr(c, "_is_polymorphic_discriminator", False) and (
2954 self.polymorphic_on is None
2955 or c.columns[0] is not self.polymorphic_on
2956 ):
2957 continue
2958 yield c
2960 @HasMemoized.memoized_attribute
2961 def attrs(self) -> util.ReadOnlyProperties[MapperProperty[Any]]:
2962 """A namespace of all :class:`.MapperProperty` objects
2963 associated this mapper.
2965 This is an object that provides each property based on
2966 its key name. For instance, the mapper for a
2967 ``User`` class which has ``User.name`` attribute would
2968 provide ``mapper.attrs.name``, which would be the
2969 :class:`.ColumnProperty` representing the ``name``
2970 column. The namespace object can also be iterated,
2971 which would yield each :class:`.MapperProperty`.
2973 :class:`_orm.Mapper` has several pre-filtered views
2974 of this attribute which limit the types of properties
2975 returned, including :attr:`.synonyms`, :attr:`.column_attrs`,
2976 :attr:`.relationships`, and :attr:`.composites`.
2978 .. warning::
2980 The :attr:`_orm.Mapper.attrs` accessor namespace is an
2981 instance of :class:`.OrderedProperties`. This is
2982 a dictionary-like object which includes a small number of
2983 named methods such as :meth:`.OrderedProperties.items`
2984 and :meth:`.OrderedProperties.values`. When
2985 accessing attributes dynamically, favor using the dict-access
2986 scheme, e.g. ``mapper.attrs[somename]`` over
2987 ``getattr(mapper.attrs, somename)`` to avoid name collisions.
2989 .. seealso::
2991 :attr:`_orm.Mapper.all_orm_descriptors`
2993 """
2995 self._check_configure()
2996 return util.ReadOnlyProperties(self._props)
2998 @HasMemoized.memoized_attribute
2999 def all_orm_descriptors(self) -> util.ReadOnlyProperties[InspectionAttr]:
3000 """A namespace of all :class:`.InspectionAttr` attributes associated
3001 with the mapped class.
3003 These attributes are in all cases Python :term:`descriptors`
3004 associated with the mapped class or its superclasses.
3006 This namespace includes attributes that are mapped to the class
3007 as well as attributes declared by extension modules.
3008 It includes any Python descriptor type that inherits from
3009 :class:`.InspectionAttr`. This includes
3010 :class:`.QueryableAttribute`, as well as extension types such as
3011 :class:`.hybrid_property`, :class:`.hybrid_method` and
3012 :class:`.AssociationProxy`.
3014 To distinguish between mapped attributes and extension attributes,
3015 the attribute :attr:`.InspectionAttr.extension_type` will refer
3016 to a constant that distinguishes between different extension types.
3018 The sorting of the attributes is based on the following rules:
3020 1. Iterate through the class and its superclasses in order from
3021 subclass to superclass (i.e. iterate through ``cls.__mro__``)
3023 2. For each class, yield the attributes in the order in which they
3024 appear in ``__dict__``, with the exception of those in step
3025 3 below. The order will be the
3026 same as that of the class' construction, with the exception
3027 of attributes that were added after the fact by the application
3028 or the mapper.
3030 3. If a certain attribute key is also in the superclass ``__dict__``,
3031 then it's included in the iteration for that class, and not the
3032 class in which it first appeared.
3034 The above process produces an ordering that is deterministic in terms
3035 of the order in which attributes were assigned to the class.
3037 When dealing with a :class:`.QueryableAttribute`, the
3038 :attr:`.QueryableAttribute.property` attribute refers to the
3039 :class:`.MapperProperty` property, which is what you get when
3040 referring to the collection of mapped properties via
3041 :attr:`_orm.Mapper.attrs`.
3043 .. warning::
3045 The :attr:`_orm.Mapper.all_orm_descriptors`
3046 accessor namespace is an
3047 instance of :class:`.OrderedProperties`. This is
3048 a dictionary-like object which includes a small number of
3049 named methods such as :meth:`.OrderedProperties.items`
3050 and :meth:`.OrderedProperties.values`. When
3051 accessing attributes dynamically, favor using the dict-access
3052 scheme, e.g. ``mapper.all_orm_descriptors[somename]`` over
3053 ``getattr(mapper.all_orm_descriptors, somename)`` to avoid name
3054 collisions.
3056 .. seealso::
3058 :attr:`_orm.Mapper.attrs`
3060 """
3061 return util.ReadOnlyProperties(
3062 dict(self.class_manager._all_sqla_attributes())
3063 )
3065 @HasMemoized.memoized_attribute
3066 @util.preload_module("sqlalchemy.orm.descriptor_props")
3067 def _pk_synonyms(self) -> Dict[str, str]:
3068 """return a dictionary of {syn_attribute_name: pk_attr_name} for
3069 all synonyms that refer to primary key columns
3071 """
3072 descriptor_props = util.preloaded.orm_descriptor_props
3074 pk_keys = {prop.key for prop in self._identity_key_props}
3076 return {
3077 syn.key: syn.name
3078 for k, syn in self._props.items()
3079 if isinstance(syn, descriptor_props.SynonymProperty)
3080 and syn.name in pk_keys
3081 }
3083 @HasMemoized.memoized_attribute
3084 @util.preload_module("sqlalchemy.orm.descriptor_props")
3085 def synonyms(self) -> util.ReadOnlyProperties[SynonymProperty[Any]]:
3086 """Return a namespace of all :class:`.Synonym`
3087 properties maintained by this :class:`_orm.Mapper`.
3089 .. seealso::
3091 :attr:`_orm.Mapper.attrs` - namespace of all
3092 :class:`.MapperProperty`
3093 objects.
3095 """
3096 descriptor_props = util.preloaded.orm_descriptor_props
3098 return self._filter_properties(descriptor_props.SynonymProperty)
3100 @util.ro_non_memoized_property
3101 def entity_namespace(self) -> _EntityNamespace:
3102 return self.class_ # type: ignore[return-value]
3104 @HasMemoized.memoized_attribute
3105 def column_attrs(self) -> util.ReadOnlyProperties[ColumnProperty[Any]]:
3106 """Return a namespace of all :class:`.ColumnProperty`
3107 properties maintained by this :class:`_orm.Mapper`.
3109 .. seealso::
3111 :attr:`_orm.Mapper.attrs` - namespace of all
3112 :class:`.MapperProperty`
3113 objects.
3115 """
3116 return self._filter_properties(properties.ColumnProperty)
3118 @HasMemoized.memoized_attribute
3119 @util.preload_module("sqlalchemy.orm.relationships")
3120 def relationships(
3121 self,
3122 ) -> util.ReadOnlyProperties[RelationshipProperty[Any]]:
3123 """A namespace of all :class:`.Relationship` properties
3124 maintained by this :class:`_orm.Mapper`.
3126 .. warning::
3128 the :attr:`_orm.Mapper.relationships` accessor namespace is an
3129 instance of :class:`.OrderedProperties`. This is
3130 a dictionary-like object which includes a small number of
3131 named methods such as :meth:`.OrderedProperties.items`
3132 and :meth:`.OrderedProperties.values`. When
3133 accessing attributes dynamically, favor using the dict-access
3134 scheme, e.g. ``mapper.relationships[somename]`` over
3135 ``getattr(mapper.relationships, somename)`` to avoid name
3136 collisions.
3138 .. seealso::
3140 :attr:`_orm.Mapper.attrs` - namespace of all
3141 :class:`.MapperProperty`
3142 objects.
3144 """
3145 return self._filter_properties(
3146 util.preloaded.orm_relationships.RelationshipProperty
3147 )
3149 @HasMemoized.memoized_attribute
3150 @util.preload_module("sqlalchemy.orm.descriptor_props")
3151 def composites(self) -> util.ReadOnlyProperties[CompositeProperty[Any]]:
3152 """Return a namespace of all :class:`.Composite`
3153 properties maintained by this :class:`_orm.Mapper`.
3155 .. seealso::
3157 :attr:`_orm.Mapper.attrs` - namespace of all
3158 :class:`.MapperProperty`
3159 objects.
3161 """
3162 return self._filter_properties(
3163 util.preloaded.orm_descriptor_props.CompositeProperty
3164 )
3166 def _filter_properties(
3167 self, type_: Type[_MP]
3168 ) -> util.ReadOnlyProperties[_MP]:
3169 self._check_configure()
3170 return util.ReadOnlyProperties(
3171 util.OrderedDict(
3172 (k, v) for k, v in self._props.items() if isinstance(v, type_)
3173 )
3174 )
3176 @HasMemoized.memoized_attribute
3177 def _get_clause(self):
3178 """create a "get clause" based on the primary key. this is used
3179 by query.get() and many-to-one lazyloads to load this item
3180 by primary key.
3182 """
3183 params = [
3184 (
3185 primary_key,
3186 sql.bindparam("pk_%d" % idx, type_=primary_key.type),
3187 )
3188 for idx, primary_key in enumerate(self.primary_key, 1)
3189 ]
3190 return (
3191 sql.and_(*[k == v for (k, v) in params]),
3192 util.column_dict(params),
3193 )
3195 @HasMemoized.memoized_attribute
3196 def _equivalent_columns(self) -> _EquivalentColumnMap:
3197 """Create a map of all equivalent columns, based on
3198 the determination of column pairs that are equated to
3199 one another based on inherit condition. This is designed
3200 to work with the queries that util.polymorphic_union
3201 comes up with, which often don't include the columns from
3202 the base table directly (including the subclass table columns
3203 only).
3205 The resulting structure is a dictionary of columns mapped
3206 to lists of equivalent columns, e.g.::
3208 {tablea.col1: {tableb.col1, tablec.col1}, tablea.col2: {tabled.col2}}
3210 """ # noqa: E501
3211 result: _EquivalentColumnMap = {}
3213 def visit_binary(binary):
3214 if binary.operator == operators.eq:
3215 if binary.left in result:
3216 result[binary.left].add(binary.right)
3217 else:
3218 result[binary.left] = {binary.right}
3219 if binary.right in result:
3220 result[binary.right].add(binary.left)
3221 else:
3222 result[binary.right] = {binary.left}
3224 for mapper in self.base_mapper.self_and_descendants:
3225 if mapper.inherit_condition is not None:
3226 visitors.traverse(
3227 mapper.inherit_condition, {}, {"binary": visit_binary}
3228 )
3230 return result
3232 def _is_userland_descriptor(self, assigned_name: str, obj: Any) -> bool:
3233 if isinstance(
3234 obj,
3235 (
3236 _MappedAttribute,
3237 instrumentation.ClassManager,
3238 expression.ColumnElement,
3239 ),
3240 ):
3241 return False
3242 else:
3243 return assigned_name not in self._dataclass_fields
3245 @HasMemoized.memoized_attribute
3246 def _dataclass_fields(self):
3247 return [f.name for f in util.dataclass_fields(self.class_)]
3249 def _should_exclude(self, name, assigned_name, local, column):
3250 """determine whether a particular property should be implicitly
3251 present on the class.
3253 This occurs when properties are propagated from an inherited class, or
3254 are applied from the columns present in the mapped table.
3256 """
3258 if column is not None and sql_base._never_select_column(column):
3259 return True
3261 # check for class-bound attributes and/or descriptors,
3262 # either local or from an inherited class
3263 # ignore dataclass field default values
3264 if local:
3265 if self.class_.__dict__.get(
3266 assigned_name, None
3267 ) is not None and self._is_userland_descriptor(
3268 assigned_name, self.class_.__dict__[assigned_name]
3269 ):
3270 return True
3271 else:
3272 attr = self.class_manager._get_class_attr_mro(assigned_name, None)
3273 if attr is not None and self._is_userland_descriptor(
3274 assigned_name, attr
3275 ):
3276 return True
3278 if (
3279 self.include_properties is not None
3280 and name not in self.include_properties
3281 and (column is None or column not in self.include_properties)
3282 ):
3283 self._log("not including property %s" % (name))
3284 return True
3286 if self.exclude_properties is not None and (
3287 name in self.exclude_properties
3288 or (column is not None and column in self.exclude_properties)
3289 ):
3290 self._log("excluding property %s" % (name))
3291 return True
3293 return False
3295 def common_parent(self, other: Mapper[Any]) -> bool:
3296 """Return true if the given mapper shares a
3297 common inherited parent as this mapper."""
3299 return self.base_mapper is other.base_mapper
3301 def is_sibling(self, other: Mapper[Any]) -> bool:
3302 """return true if the other mapper is an inheriting sibling to this
3303 one. common parent but different branch
3305 """
3306 return (
3307 self.base_mapper is other.base_mapper
3308 and not self.isa(other)
3309 and not other.isa(self)
3310 )
3312 def _canload(
3313 self, state: InstanceState[Any], allow_subtypes: bool
3314 ) -> bool:
3315 s = self.primary_mapper()
3316 if self.polymorphic_on is not None or allow_subtypes:
3317 return _state_mapper(state).isa(s)
3318 else:
3319 return _state_mapper(state) is s
3321 def isa(self, other: Mapper[Any]) -> bool:
3322 """Return True if the this mapper inherits from the given mapper."""
3324 m: Optional[Mapper[Any]] = self
3325 while m and m is not other:
3326 m = m.inherits
3327 return bool(m)
3329 def iterate_to_root(self) -> Iterator[Mapper[Any]]:
3330 m: Optional[Mapper[Any]] = self
3331 while m:
3332 yield m
3333 m = m.inherits
3335 @HasMemoized.memoized_attribute
3336 def self_and_descendants(self) -> Sequence[Mapper[Any]]:
3337 """The collection including this mapper and all descendant mappers.
3339 This includes not just the immediately inheriting mappers but
3340 all their inheriting mappers as well.
3342 """
3343 descendants = []
3344 stack = deque([self])
3345 while stack:
3346 item = stack.popleft()
3347 descendants.append(item)
3348 stack.extend(item._inheriting_mappers)
3349 return util.WeakSequence(descendants)
3351 def polymorphic_iterator(self) -> Iterator[Mapper[Any]]:
3352 """Iterate through the collection including this mapper and
3353 all descendant mappers.
3355 This includes not just the immediately inheriting mappers but
3356 all their inheriting mappers as well.
3358 To iterate through an entire hierarchy, use
3359 ``mapper.base_mapper.polymorphic_iterator()``.
3361 """
3362 return iter(self.self_and_descendants)
3364 def primary_mapper(self) -> Mapper[Any]:
3365 """Return the primary mapper corresponding to this mapper's class key
3366 (class)."""
3368 return self.class_manager.mapper
3370 @property
3371 def primary_base_mapper(self) -> Mapper[Any]:
3372 return self.class_manager.mapper.base_mapper
3374 def _result_has_identity_key(self, result, adapter=None):
3375 pk_cols: Sequence[ColumnElement[Any]]
3376 if adapter is not None:
3377 pk_cols = [adapter.columns[c] for c in self.primary_key]
3378 else:
3379 pk_cols = self.primary_key
3380 rk = result.keys()
3381 for col in pk_cols:
3382 if col not in rk:
3383 return False
3384 else:
3385 return True
3387 def identity_key_from_row(
3388 self,
3389 row: Union[Row[Unpack[TupleAny]], RowMapping],
3390 identity_token: Optional[Any] = None,
3391 adapter: Optional[ORMAdapter] = None,
3392 ) -> _IdentityKeyType[_O]:
3393 """Return an identity-map key for use in storing/retrieving an
3394 item from the identity map.
3396 :param row: A :class:`.Row` or :class:`.RowMapping` produced from a
3397 result set that selected from the ORM mapped primary key columns.
3399 .. versionchanged:: 2.0
3400 :class:`.Row` or :class:`.RowMapping` are accepted
3401 for the "row" argument
3403 """
3404 pk_cols: Sequence[ColumnElement[Any]]
3405 if adapter is not None:
3406 pk_cols = [adapter.columns[c] for c in self.primary_key]
3407 else:
3408 pk_cols = self.primary_key
3410 mapping: RowMapping
3411 if hasattr(row, "_mapping"):
3412 mapping = row._mapping
3413 else:
3414 mapping = row # type: ignore[assignment]
3416 return (
3417 self._identity_class,
3418 tuple(mapping[column] for column in pk_cols),
3419 identity_token,
3420 )
3422 def identity_key_from_primary_key(
3423 self,
3424 primary_key: Tuple[Any, ...],
3425 identity_token: Optional[Any] = None,
3426 ) -> _IdentityKeyType[_O]:
3427 """Return an identity-map key for use in storing/retrieving an
3428 item from an identity map.
3430 :param primary_key: A list of values indicating the identifier.
3432 """
3433 return (
3434 self._identity_class,
3435 tuple(primary_key),
3436 identity_token,
3437 )
3439 def identity_key_from_instance(self, instance: _O) -> _IdentityKeyType[_O]:
3440 """Return the identity key for the given instance, based on
3441 its primary key attributes.
3443 If the instance's state is expired, calling this method
3444 will result in a database check to see if the object has been deleted.
3445 If the row no longer exists,
3446 :class:`~sqlalchemy.orm.exc.ObjectDeletedError` is raised.
3448 This value is typically also found on the instance state under the
3449 attribute name `key`.
3451 """
3452 state = attributes.instance_state(instance)
3453 return self._identity_key_from_state(state, PassiveFlag.PASSIVE_OFF)
3455 def _identity_key_from_state(
3456 self,
3457 state: InstanceState[_O],
3458 passive: PassiveFlag = PassiveFlag.PASSIVE_RETURN_NO_VALUE,
3459 ) -> _IdentityKeyType[_O]:
3460 dict_ = state.dict
3461 manager = state.manager
3462 return (
3463 self._identity_class,
3464 tuple(
3465 [
3466 manager[prop.key].impl.get(state, dict_, passive)
3467 for prop in self._identity_key_props
3468 ]
3469 ),
3470 state.identity_token,
3471 )
3473 def primary_key_from_instance(self, instance: _O) -> Tuple[Any, ...]:
3474 """Return the list of primary key values for the given
3475 instance.
3477 If the instance's state is expired, calling this method
3478 will result in a database check to see if the object has been deleted.
3479 If the row no longer exists,
3480 :class:`~sqlalchemy.orm.exc.ObjectDeletedError` is raised.
3482 """
3483 state = attributes.instance_state(instance)
3484 identity_key = self._identity_key_from_state(
3485 state, PassiveFlag.PASSIVE_OFF
3486 )
3487 return identity_key[1]
3489 @HasMemoized.memoized_attribute
3490 def _persistent_sortkey_fn(self):
3491 key_fns = [col.type.sort_key_function for col in self.primary_key]
3493 if set(key_fns).difference([None]):
3495 def key(state):
3496 return tuple(
3497 key_fn(val) if key_fn is not None else val
3498 for key_fn, val in zip(key_fns, state.key[1])
3499 )
3501 else:
3503 def key(state):
3504 return state.key[1]
3506 return key
3508 @HasMemoized.memoized_attribute
3509 def _identity_key_props(self):
3510 return [self._columntoproperty[col] for col in self.primary_key]
3512 @HasMemoized.memoized_attribute
3513 def _all_pk_cols(self):
3514 collection: Set[ColumnClause[Any]] = set()
3515 for table in self.tables:
3516 collection.update(self._pks_by_table[table])
3517 return collection
3519 @HasMemoized.memoized_attribute
3520 def _should_undefer_in_wildcard(self):
3521 cols: Set[ColumnElement[Any]] = set(self.primary_key)
3522 if self.polymorphic_on is not None:
3523 cols.add(self.polymorphic_on)
3524 return cols
3526 @HasMemoized.memoized_attribute
3527 def _primary_key_propkeys(self):
3528 return {self._columntoproperty[col].key for col in self._all_pk_cols}
3530 def _get_state_attr_by_column(
3531 self,
3532 state: InstanceState[_O],
3533 dict_: _InstanceDict,
3534 column: ColumnElement[Any],
3535 passive: PassiveFlag = PassiveFlag.PASSIVE_RETURN_NO_VALUE,
3536 ) -> Any:
3537 prop = self._columntoproperty[column]
3538 return state.manager[prop.key].impl.get(state, dict_, passive=passive)
3540 def _set_committed_state_attr_by_column(self, state, dict_, column, value):
3541 prop = self._columntoproperty[column]
3542 state.manager[prop.key].impl.set_committed_value(state, dict_, value)
3544 def _set_state_attr_by_column(self, state, dict_, column, value):
3545 prop = self._columntoproperty[column]
3546 state.manager[prop.key].impl.set(state, dict_, value, None)
3548 def _get_committed_attr_by_column(self, obj, column):
3549 state = attributes.instance_state(obj)
3550 dict_ = attributes.instance_dict(obj)
3551 return self._get_committed_state_attr_by_column(
3552 state, dict_, column, passive=PassiveFlag.PASSIVE_OFF
3553 )
3555 def _get_committed_state_attr_by_column(
3556 self, state, dict_, column, passive=PassiveFlag.PASSIVE_RETURN_NO_VALUE
3557 ):
3558 prop = self._columntoproperty[column]
3559 return state.manager[prop.key].impl.get_committed_value(
3560 state, dict_, passive=passive
3561 )
3563 def _optimized_get_statement(self, state, attribute_names):
3564 """assemble a WHERE clause which retrieves a given state by primary
3565 key, using a minimized set of tables.
3567 Applies to a joined-table inheritance mapper where the
3568 requested attribute names are only present on joined tables,
3569 not the base table. The WHERE clause attempts to include
3570 only those tables to minimize joins.
3572 """
3573 props = self._props
3575 col_attribute_names = set(attribute_names).intersection(
3576 state.mapper.column_attrs.keys()
3577 )
3578 tables: Set[FromClause] = set(
3579 chain(
3580 *[
3581 sql_util.find_tables(c, check_columns=True)
3582 for key in col_attribute_names
3583 for c in props[key].columns
3584 ]
3585 )
3586 )
3588 if self.base_mapper.local_table in tables:
3589 return None
3591 def visit_binary(binary):
3592 leftcol = binary.left
3593 rightcol = binary.right
3594 if leftcol is None or rightcol is None:
3595 return
3597 if leftcol.table not in tables:
3598 leftval = self._get_committed_state_attr_by_column(
3599 state,
3600 state.dict,
3601 leftcol,
3602 passive=PassiveFlag.PASSIVE_NO_INITIALIZE,
3603 )
3604 if leftval in orm_util._none_set:
3605 raise _OptGetColumnsNotAvailable()
3606 binary.left = sql.bindparam(
3607 None, leftval, type_=binary.right.type
3608 )
3609 elif rightcol.table not in tables:
3610 rightval = self._get_committed_state_attr_by_column(
3611 state,
3612 state.dict,
3613 rightcol,
3614 passive=PassiveFlag.PASSIVE_NO_INITIALIZE,
3615 )
3616 if rightval in orm_util._none_set:
3617 raise _OptGetColumnsNotAvailable()
3618 binary.right = sql.bindparam(
3619 None, rightval, type_=binary.right.type
3620 )
3622 allconds: List[ColumnElement[bool]] = []
3624 start = False
3626 # as of #7507, from the lowest base table on upwards,
3627 # we include all intermediary tables.
3629 for mapper in reversed(list(self.iterate_to_root())):
3630 if mapper.local_table in tables:
3631 start = True
3632 elif not isinstance(mapper.local_table, expression.TableClause):
3633 return None
3634 if start and not mapper.single:
3635 assert mapper.inherits
3636 assert not mapper.concrete
3637 assert mapper.inherit_condition is not None
3638 allconds.append(mapper.inherit_condition)
3639 tables.add(mapper.local_table)
3641 # only the bottom table needs its criteria to be altered to fit
3642 # the primary key ident - the rest of the tables upwards to the
3643 # descendant-most class should all be present and joined to each
3644 # other.
3645 try:
3646 _traversed = visitors.cloned_traverse(
3647 allconds[0], {}, {"binary": visit_binary}
3648 )
3649 except _OptGetColumnsNotAvailable:
3650 return None
3651 else:
3652 allconds[0] = _traversed
3654 cond = sql.and_(*allconds)
3656 cols = []
3657 for key in col_attribute_names:
3658 cols.extend(props[key].columns)
3659 return (
3660 sql.select(*cols)
3661 .where(cond)
3662 .set_label_style(LABEL_STYLE_TABLENAME_PLUS_COL)
3663 )
3665 def _iterate_to_target_viawpoly(self, mapper):
3666 if self.isa(mapper):
3667 prev = self
3668 for m in self.iterate_to_root():
3669 yield m
3671 if m is not prev and prev not in m._with_polymorphic_mappers:
3672 break
3674 prev = m
3675 if m is mapper:
3676 break
3678 @HasMemoized.memoized_attribute
3679 def _would_selectinload_combinations_cache(self):
3680 return {}
3682 def _would_selectin_load_only_from_given_mapper(self, super_mapper):
3683 """return True if this mapper would "selectin" polymorphic load based
3684 on the given super mapper, and not from a setting from a subclass.
3686 given::
3688 class A: ...
3691 class B(A):
3692 __mapper_args__ = {"polymorphic_load": "selectin"}
3695 class C(B): ...
3698 class D(B):
3699 __mapper_args__ = {"polymorphic_load": "selectin"}
3701 ``inspect(C)._would_selectin_load_only_from_given_mapper(inspect(B))``
3702 returns True, because C does selectin loading because of B's setting.
3704 OTOH, ``inspect(D)
3705 ._would_selectin_load_only_from_given_mapper(inspect(B))``
3706 returns False, because D does selectin loading because of its own
3707 setting; when we are doing a selectin poly load from B, we want to
3708 filter out D because it would already have its own selectin poly load
3709 set up separately.
3711 Added as part of #9373.
3713 """
3714 cache = self._would_selectinload_combinations_cache
3716 try:
3717 return cache[super_mapper]
3718 except KeyError:
3719 pass
3721 # assert that given object is a supermapper, meaning we already
3722 # strong reference it directly or indirectly. this allows us
3723 # to not worry that we are creating new strongrefs to unrelated
3724 # mappers or other objects.
3725 assert self.isa(super_mapper)
3727 mapper = super_mapper
3728 for m in self._iterate_to_target_viawpoly(mapper):
3729 if m.polymorphic_load == "selectin":
3730 retval = m is super_mapper
3731 break
3732 else:
3733 retval = False
3735 cache[super_mapper] = retval
3736 return retval
3738 def _should_selectin_load(self, enabled_via_opt, polymorphic_from):
3739 if not enabled_via_opt:
3740 # common case, takes place for all polymorphic loads
3741 mapper = polymorphic_from
3742 for m in self._iterate_to_target_viawpoly(mapper):
3743 if m.polymorphic_load == "selectin":
3744 return m
3745 else:
3746 # uncommon case, selectin load options were used
3747 enabled_via_opt = set(enabled_via_opt)
3748 enabled_via_opt_mappers = {e.mapper: e for e in enabled_via_opt}
3749 for entity in enabled_via_opt.union([polymorphic_from]):
3750 mapper = entity.mapper
3751 for m in self._iterate_to_target_viawpoly(mapper):
3752 if (
3753 m.polymorphic_load == "selectin"
3754 or m in enabled_via_opt_mappers
3755 ):
3756 return enabled_via_opt_mappers.get(m, m)
3758 return None
3760 @util.preload_module("sqlalchemy.orm.strategy_options")
3761 def _subclass_load_via_in(self, entity, polymorphic_from):
3762 """Assemble a that can load the columns local to
3763 this subclass as a SELECT with IN.
3765 """
3767 strategy_options = util.preloaded.orm_strategy_options
3769 assert self.inherits
3771 if self.polymorphic_on is not None:
3772 polymorphic_prop = self._columntoproperty[self.polymorphic_on]
3773 keep_props = set([polymorphic_prop] + self._identity_key_props)
3774 else:
3775 keep_props = set(self._identity_key_props)
3777 disable_opt = strategy_options.Load(entity)
3778 enable_opt = strategy_options.Load(entity)
3780 classes_to_include = {self}
3781 m: Optional[Mapper[Any]] = self.inherits
3782 while (
3783 m is not None
3784 and m is not polymorphic_from
3785 and m.polymorphic_load == "selectin"
3786 ):
3787 classes_to_include.add(m)
3788 m = m.inherits
3790 for prop in self.column_attrs + self.relationships:
3791 # skip prop keys that are not instrumented on the mapped class.
3792 # this is primarily the "_sa_polymorphic_on" property that gets
3793 # created for an ad-hoc polymorphic_on SQL expression, issue #8704
3794 if prop.key not in self.class_manager:
3795 continue
3797 if prop.parent in classes_to_include or prop in keep_props:
3798 # "enable" options, to turn on the properties that we want to
3799 # load by default (subject to options from the query)
3800 if not isinstance(prop, StrategizedProperty):
3801 continue
3803 enable_opt = enable_opt._set_generic_strategy(
3804 # convert string name to an attribute before passing
3805 # to loader strategy. note this must be in terms
3806 # of given entity, such as AliasedClass, etc.
3807 (getattr(entity.entity_namespace, prop.key),),
3808 dict(prop.strategy_key),
3809 _reconcile_to_other=True,
3810 )
3811 else:
3812 # "disable" options, to turn off the properties from the
3813 # superclass that we *don't* want to load, applied after
3814 # the options from the query to override them
3815 disable_opt = disable_opt._set_generic_strategy(
3816 # convert string name to an attribute before passing
3817 # to loader strategy. note this must be in terms
3818 # of given entity, such as AliasedClass, etc.
3819 (getattr(entity.entity_namespace, prop.key),),
3820 {"do_nothing": True},
3821 _reconcile_to_other=False,
3822 )
3824 primary_key = [
3825 sql_util._deep_annotate(pk, {"_orm_adapt": True})
3826 for pk in self.primary_key
3827 ]
3829 in_expr: ColumnElement[Any]
3831 if len(primary_key) > 1:
3832 in_expr = sql.tuple_(*primary_key)
3833 else:
3834 in_expr = primary_key[0]
3836 if entity.is_aliased_class:
3837 assert entity.mapper is self
3839 q = sql.select(entity).set_label_style(
3840 LABEL_STYLE_TABLENAME_PLUS_COL
3841 )
3843 in_expr = entity._adapter.traverse(in_expr)
3844 primary_key = [entity._adapter.traverse(k) for k in primary_key]
3845 q = q.where(
3846 in_expr.in_(sql.bindparam("primary_keys", expanding=True))
3847 ).order_by(*primary_key)
3848 else:
3849 q = sql.select(self).set_label_style(
3850 LABEL_STYLE_TABLENAME_PLUS_COL
3851 )
3852 q = q.where(
3853 in_expr.in_(sql.bindparam("primary_keys", expanding=True))
3854 ).order_by(*primary_key)
3856 return q, enable_opt, disable_opt
3858 @HasMemoized.memoized_attribute
3859 def _subclass_load_via_in_mapper(self):
3860 # the default is loading this mapper against the basemost mapper
3861 return self._subclass_load_via_in(self, self.base_mapper)
3863 def cascade_iterator(
3864 self,
3865 type_: str,
3866 state: InstanceState[_O],
3867 halt_on: Optional[Callable[[InstanceState[Any]], bool]] = None,
3868 ) -> Iterator[
3869 Tuple[object, Mapper[Any], InstanceState[Any], _InstanceDict]
3870 ]:
3871 r"""Iterate each element and its mapper in an object graph,
3872 for all relationships that meet the given cascade rule.
3874 :param type\_:
3875 The name of the cascade rule (i.e. ``"save-update"``, ``"delete"``,
3876 etc.).
3878 .. note:: the ``"all"`` cascade is not accepted here. For a generic
3879 object traversal function, see :ref:`faq_walk_objects`.
3881 :param state:
3882 The lead InstanceState. child items will be processed per
3883 the relationships defined for this object's mapper.
3885 :return: the method yields individual object instances.
3887 .. seealso::
3889 :ref:`unitofwork_cascades`
3891 :ref:`faq_walk_objects` - illustrates a generic function to
3892 traverse all objects without relying on cascades.
3894 """
3895 visited_states: Set[InstanceState[Any]] = set()
3896 prp, mpp = object(), object()
3898 assert state.mapper.isa(self)
3900 # this is actually a recursive structure, fully typing it seems
3901 # a little too difficult for what it's worth here
3902 visitables: Deque[
3903 Tuple[
3904 Deque[Any],
3905 object,
3906 Optional[InstanceState[Any]],
3907 Optional[_InstanceDict],
3908 ]
3909 ]
3911 visitables = deque(
3912 [(deque(state.mapper._props.values()), prp, state, state.dict)]
3913 )
3915 while visitables:
3916 iterator, item_type, parent_state, parent_dict = visitables[-1]
3917 if not iterator:
3918 visitables.pop()
3919 continue
3921 if item_type is prp:
3922 prop = iterator.popleft()
3923 if not prop.cascade or type_ not in prop.cascade:
3924 continue
3925 assert parent_state is not None
3926 assert parent_dict is not None
3927 queue = deque(
3928 prop.cascade_iterator(
3929 type_,
3930 parent_state,
3931 parent_dict,
3932 visited_states,
3933 halt_on,
3934 )
3935 )
3936 if queue:
3937 visitables.append((queue, mpp, None, None))
3938 elif item_type is mpp:
3939 (
3940 instance,
3941 instance_mapper,
3942 corresponding_state,
3943 corresponding_dict,
3944 ) = iterator.popleft()
3945 yield (
3946 instance,
3947 instance_mapper,
3948 corresponding_state,
3949 corresponding_dict,
3950 )
3951 visitables.append(
3952 (
3953 deque(instance_mapper._props.values()),
3954 prp,
3955 corresponding_state,
3956 corresponding_dict,
3957 )
3958 )
3960 @HasMemoized.memoized_attribute
3961 def _compiled_cache(self):
3962 return util.LRUCache(self._compiled_cache_size)
3964 @HasMemoized.memoized_attribute
3965 def _multiple_persistence_tables(self):
3966 return len(self.tables) > 1
3968 @HasMemoized.memoized_attribute
3969 def _sorted_tables(self):
3970 table_to_mapper: Dict[TableClause, Mapper[Any]] = {}
3972 for mapper in self.base_mapper.self_and_descendants:
3973 for t in mapper.tables:
3974 table_to_mapper.setdefault(t, mapper)
3976 extra_dependencies = []
3977 for table, mapper in table_to_mapper.items():
3978 super_ = mapper.inherits
3979 if super_:
3980 extra_dependencies.extend(
3981 [(super_table, table) for super_table in super_.tables]
3982 )
3984 def skip(fk):
3985 # attempt to skip dependencies that are not
3986 # significant to the inheritance chain
3987 # for two tables that are related by inheritance.
3988 # while that dependency may be important, it's technically
3989 # not what we mean to sort on here.
3990 parent = table_to_mapper.get(fk.parent.table)
3991 dep = table_to_mapper.get(fk.column.table)
3992 if (
3993 parent is not None
3994 and dep is not None
3995 and dep is not parent
3996 and dep.inherit_condition is not None
3997 ):
3998 cols = set(sql_util._find_columns(dep.inherit_condition))
3999 if parent.inherit_condition is not None:
4000 cols = cols.union(
4001 sql_util._find_columns(parent.inherit_condition)
4002 )
4003 return fk.parent not in cols and fk.column not in cols
4004 else:
4005 return fk.parent not in cols
4006 return False
4008 sorted_ = sql_util.sort_tables(
4009 table_to_mapper,
4010 skip_fn=skip,
4011 extra_dependencies=extra_dependencies,
4012 )
4014 ret = util.OrderedDict()
4015 for t in sorted_:
4016 ret[t] = table_to_mapper[t]
4017 return ret
4019 def _memo(self, key: Any, callable_: Callable[[], _T]) -> _T:
4020 if key in self._memoized_values:
4021 return cast(_T, self._memoized_values[key])
4022 else:
4023 self._memoized_values[key] = value = callable_()
4024 return value
4026 @util.memoized_property
4027 def _table_to_equated(self):
4028 """memoized map of tables to collections of columns to be
4029 synchronized upwards to the base mapper."""
4031 result: util.defaultdict[
4032 Table,
4033 List[
4034 Tuple[
4035 Mapper[Any],
4036 List[Tuple[ColumnElement[Any], ColumnElement[Any]]],
4037 ]
4038 ],
4039 ] = util.defaultdict(list)
4041 def set_union(x, y):
4042 return x.union(y)
4044 for table in self._sorted_tables:
4045 cols = set(table.c)
4047 for m in self.iterate_to_root():
4048 if m._inherits_equated_pairs and cols.intersection(
4049 reduce(
4050 set_union,
4051 [l.proxy_set for l, r in m._inherits_equated_pairs],
4052 )
4053 ):
4054 result[table].append((m, m._inherits_equated_pairs))
4056 return result
4059class _OptGetColumnsNotAvailable(Exception):
4060 pass
4063def configure_mappers() -> None:
4064 """Initialize the inter-mapper relationships of all mappers that
4065 have been constructed thus far across all :class:`_orm.registry`
4066 collections.
4068 The configure step is used to reconcile and initialize the
4069 :func:`_orm.relationship` linkages between mapped classes, as well as to
4070 invoke configuration events such as the
4071 :meth:`_orm.MapperEvents.before_configured` and
4072 :meth:`_orm.MapperEvents.after_configured`, which may be used by ORM
4073 extensions or user-defined extension hooks.
4075 Mapper configuration is normally invoked automatically, the first time
4076 mappings from a particular :class:`_orm.registry` are used, as well as
4077 whenever mappings are used and additional not-yet-configured mappers have
4078 been constructed. The automatic configuration process however is local only
4079 to the :class:`_orm.registry` involving the target mapper and any related
4080 :class:`_orm.registry` objects which it may depend on; this is
4081 equivalent to invoking the :meth:`_orm.registry.configure` method
4082 on a particular :class:`_orm.registry`.
4084 By contrast, the :func:`_orm.configure_mappers` function will invoke the
4085 configuration process on all :class:`_orm.registry` objects that
4086 exist in memory, and may be useful for scenarios where many individual
4087 :class:`_orm.registry` objects that are nonetheless interrelated are
4088 in use.
4090 .. versionchanged:: 1.4
4092 As of SQLAlchemy 1.4.0b2, this function works on a
4093 per-:class:`_orm.registry` basis, locating all :class:`_orm.registry`
4094 objects present and invoking the :meth:`_orm.registry.configure` method
4095 on each. The :meth:`_orm.registry.configure` method may be preferred to
4096 limit the configuration of mappers to those local to a particular
4097 :class:`_orm.registry` and/or declarative base class.
4099 Points at which automatic configuration is invoked include when a mapped
4100 class is instantiated into an instance, as well as when ORM queries
4101 are emitted using :meth:`.Session.query` or :meth:`_orm.Session.execute`
4102 with an ORM-enabled statement.
4104 The mapper configure process, whether invoked by
4105 :func:`_orm.configure_mappers` or from :meth:`_orm.registry.configure`,
4106 provides several event hooks that can be used to augment the mapper
4107 configuration step. These hooks include:
4109 * :meth:`.MapperEvents.before_configured` - called once before
4110 :func:`.configure_mappers` or :meth:`_orm.registry.configure` does any
4111 work; this can be used to establish additional options, properties, or
4112 related mappings before the operation proceeds.
4114 * :meth:`.MapperEvents.mapper_configured` - called as each individual
4115 :class:`_orm.Mapper` is configured within the process; will include all
4116 mapper state except for backrefs set up by other mappers that are still
4117 to be configured.
4119 * :meth:`.MapperEvents.after_configured` - called once after
4120 :func:`.configure_mappers` or :meth:`_orm.registry.configure` is
4121 complete; at this stage, all :class:`_orm.Mapper` objects that fall
4122 within the scope of the configuration operation will be fully configured.
4123 Note that the calling application may still have other mappings that
4124 haven't been produced yet, such as if they are in modules as yet
4125 unimported, and may also have mappings that are still to be configured,
4126 if they are in other :class:`_orm.registry` collections not part of the
4127 current scope of configuration.
4129 """
4131 _configure_registries(_all_registries(), cascade=True)
4134def _configure_registries(
4135 registries: Set[_RegistryType], cascade: bool
4136) -> None:
4137 for reg in registries:
4138 if reg._new_mappers:
4139 break
4140 else:
4141 return
4143 with _CONFIGURE_MUTEX:
4144 global _already_compiling
4145 if _already_compiling:
4146 return
4147 _already_compiling = True
4148 try:
4149 # double-check inside mutex
4150 for reg in registries:
4151 if reg._new_mappers:
4152 break
4153 else:
4154 return
4156 Mapper.dispatch._for_class(Mapper).before_configured() # type: ignore # noqa: E501
4157 # initialize properties on all mappers
4158 # note that _mapper_registry is unordered, which
4159 # may randomly conceal/reveal issues related to
4160 # the order of mapper compilation
4162 _do_configure_registries(registries, cascade)
4163 finally:
4164 _already_compiling = False
4165 Mapper.dispatch._for_class(Mapper).after_configured() # type: ignore
4168@util.preload_module("sqlalchemy.orm.decl_api")
4169def _do_configure_registries(
4170 registries: Set[_RegistryType], cascade: bool
4171) -> None:
4172 registry = util.preloaded.orm_decl_api.registry
4174 orig = set(registries)
4176 for reg in registry._recurse_with_dependencies(registries):
4177 has_skip = False
4179 for mapper in reg._mappers_to_configure():
4180 run_configure = None
4182 for fn in mapper.dispatch.before_mapper_configured:
4183 run_configure = fn(mapper, mapper.class_)
4184 if run_configure is EXT_SKIP:
4185 has_skip = True
4186 break
4187 if run_configure is EXT_SKIP:
4188 continue
4190 if getattr(mapper, "_configure_failed", False):
4191 e = sa_exc.InvalidRequestError(
4192 "One or more mappers failed to initialize - "
4193 "can't proceed with initialization of other "
4194 "mappers. Triggering mapper: '%s'. "
4195 "Original exception was: %s"
4196 % (mapper, mapper._configure_failed)
4197 )
4198 e._configure_failed = mapper._configure_failed # type: ignore
4199 raise e
4201 if not mapper.configured:
4202 try:
4203 mapper._post_configure_properties()
4204 mapper._expire_memoizations()
4205 mapper.dispatch.mapper_configured(mapper, mapper.class_)
4206 except Exception:
4207 exc = sys.exc_info()[1]
4208 if not hasattr(exc, "_configure_failed"):
4209 mapper._configure_failed = exc
4210 raise
4211 if not has_skip:
4212 reg._new_mappers = False
4214 if not cascade and reg._dependencies.difference(orig):
4215 raise sa_exc.InvalidRequestError(
4216 "configure was called with cascade=False but "
4217 "additional registries remain"
4218 )
4221@util.preload_module("sqlalchemy.orm.decl_api")
4222def _dispose_registries(registries: Set[_RegistryType], cascade: bool) -> None:
4223 registry = util.preloaded.orm_decl_api.registry
4225 orig = set(registries)
4227 for reg in registry._recurse_with_dependents(registries):
4228 if not cascade and reg._dependents.difference(orig):
4229 raise sa_exc.InvalidRequestError(
4230 "Registry has dependent registries that are not disposed; "
4231 "pass cascade=True to clear these also"
4232 )
4234 while reg._managers:
4235 try:
4236 manager, _ = reg._managers.popitem()
4237 except KeyError:
4238 # guard against race between while and popitem
4239 pass
4240 else:
4241 reg._dispose_manager_and_mapper(manager)
4243 reg._dependents.clear()
4244 for dep in reg._dependencies:
4245 dep._dependents.discard(reg)
4246 reg._dependencies.clear()
4247 # this wasn't done in the 1.3 clear_mappers() and in fact it
4248 # was a bug, as it could cause configure_mappers() to invoke
4249 # the "before_configured" event even though mappers had all been
4250 # disposed.
4251 reg._new_mappers = False
4254def reconstructor(fn: _Fn) -> _Fn:
4255 """Decorate a method as the 'reconstructor' hook.
4257 Designates a single method as the "reconstructor", an ``__init__``-like
4258 method that will be called by the ORM after the instance has been
4259 loaded from the database or otherwise reconstituted.
4261 .. tip::
4263 The :func:`_orm.reconstructor` decorator makes use of the
4264 :meth:`_orm.InstanceEvents.load` event hook, which can be
4265 used directly.
4267 The reconstructor will be invoked with no arguments. Scalar
4268 (non-collection) database-mapped attributes of the instance will
4269 be available for use within the function. Eagerly-loaded
4270 collections are generally not yet available and will usually only
4271 contain the first element. ORM state changes made to objects at
4272 this stage will not be recorded for the next flush() operation, so
4273 the activity within a reconstructor should be conservative.
4275 .. seealso::
4277 :meth:`.InstanceEvents.load`
4279 """
4280 fn.__sa_reconstructor__ = True # type: ignore[attr-defined]
4281 return fn
4284def validates(
4285 *names: str, include_removes: bool = False, include_backrefs: bool = True
4286) -> Callable[[_Fn], _Fn]:
4287 r"""Decorate a method as a 'validator' for one or more named properties.
4289 Designates a method as a validator, a method which receives the
4290 name of the attribute as well as a value to be assigned, or in the
4291 case of a collection, the value to be added to the collection.
4292 The function can then raise validation exceptions to halt the
4293 process from continuing (where Python's built-in ``ValueError``
4294 and ``AssertionError`` exceptions are reasonable choices), or can
4295 modify or replace the value before proceeding. The function should
4296 otherwise return the given value.
4298 Note that a validator for a collection **cannot** issue a load of that
4299 collection within the validation routine - this usage raises
4300 an assertion to avoid recursion overflows. This is a reentrant
4301 condition which is not supported.
4303 :param \*names: list of attribute names to be validated.
4304 :param include_removes: if True, "remove" events will be
4305 sent as well - the validation function must accept an additional
4306 argument "is_remove" which will be a boolean.
4308 :param include_backrefs: defaults to ``True``; if ``False``, the
4309 validation function will not emit if the originator is an attribute
4310 event related via a backref. This can be used for bi-directional
4311 :func:`.validates` usage where only one validator should emit per
4312 attribute operation.
4314 .. versionchanged:: 2.0.16 This paramter inadvertently defaulted to
4315 ``False`` for releases 2.0.0 through 2.0.15. Its correct default
4316 of ``True`` is restored in 2.0.16.
4318 .. seealso::
4320 :ref:`simple_validators` - usage examples for :func:`.validates`
4322 """
4324 def wrap(fn: _Fn) -> _Fn:
4325 fn.__sa_validators__ = names # type: ignore[attr-defined]
4326 fn.__sa_validation_opts__ = { # type: ignore[attr-defined]
4327 "include_removes": include_removes,
4328 "include_backrefs": include_backrefs,
4329 }
4330 return fn
4332 return wrap
4335def _event_on_load(state, ctx):
4336 instrumenting_mapper = state.manager.mapper
4338 if instrumenting_mapper._reconstructor:
4339 instrumenting_mapper._reconstructor(state.obj())
4342def _event_on_init(state, args, kwargs):
4343 """Run init_instance hooks.
4345 This also includes mapper compilation, normally not needed
4346 here but helps with some piecemeal configuration
4347 scenarios (such as in the ORM tutorial).
4349 """
4351 instrumenting_mapper = state.manager.mapper
4352 if instrumenting_mapper:
4353 instrumenting_mapper._check_configure()
4354 if instrumenting_mapper._set_polymorphic_identity:
4355 instrumenting_mapper._set_polymorphic_identity(state)
4358class _ColumnMapping(Dict["ColumnElement[Any]", "MapperProperty[Any]"]):
4359 """Error reporting helper for mapper._columntoproperty."""
4361 __slots__ = ("mapper",)
4363 def __init__(self, mapper):
4364 # TODO: weakref would be a good idea here
4365 self.mapper = mapper
4367 def __missing__(self, column):
4368 prop = self.mapper._props.get(column)
4369 if prop:
4370 raise orm_exc.UnmappedColumnError(
4371 "Column '%s.%s' is not available, due to "
4372 "conflicting property '%s':%r"
4373 % (column.table.name, column.name, column.key, prop)
4374 )
4375 raise orm_exc.UnmappedColumnError(
4376 "No column %s is configured on mapper %s..."
4377 % (column, self.mapper)
4378 )