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1# Copyright 2018 Google LLC
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7# https://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
15import collections
16import collections.abc
17import copy
18import re
19from typing import Any, Dict, List, Optional, Type
20import warnings
22import google.protobuf
23from google.protobuf import descriptor_pb2
24from google.protobuf import message
25from google.protobuf.json_format import MessageToDict, MessageToJson, Parse
27from proto import _file_info
28from proto import _package_info
29from proto.fields import Field
30from proto.fields import MapField
31from proto.fields import RepeatedField
32from proto.marshal import Marshal
33from proto.primitives import ProtoType
34from proto.utils import has_upb
37PROTOBUF_VERSION = google.protobuf.__version__
39_upb = has_upb() # Important to cache result here.
42class MessageMeta(type):
43 """A metaclass for building and registering Message subclasses."""
45 def __new__(mcls, name, bases, attrs):
46 # Do not do any special behavior for Message itself.
47 if not bases:
48 return super().__new__(mcls, name, bases, attrs)
50 # Get the essential information about the proto package, and where
51 # this component belongs within the file.
52 package, marshal = _package_info.compile(name, attrs)
54 # Determine the local path of this proto component within the file.
55 local_path = tuple(attrs.get("__qualname__", name).split("."))
57 # Sanity check: We get the wrong full name if a class is declared
58 # inside a function local scope; correct this.
59 if "<locals>" in local_path:
60 ix = local_path.index("<locals>")
61 local_path = local_path[: ix - 1] + local_path[ix + 1 :]
63 # Determine the full name in protocol buffers.
64 full_name = ".".join((package,) + local_path).lstrip(".")
66 # Special case: Maps. Map fields are special; they are essentially
67 # shorthand for a nested message and a repeated field of that message.
68 # Decompose each map into its constituent form.
69 # https://developers.google.com/protocol-buffers/docs/proto3#maps
70 map_fields = {}
71 for key, field in attrs.items():
72 if not isinstance(field, MapField):
73 continue
75 # Determine the name of the entry message.
76 msg_name = "{pascal_key}Entry".format(
77 pascal_key=re.sub(
78 r"_\w",
79 lambda m: m.group()[1:].upper(),
80 key,
81 ).replace(key[0], key[0].upper(), 1),
82 )
84 # Create the "entry" message (with the key and value fields).
85 #
86 # Note: We instantiate an ordered dictionary here and then
87 # attach key and value in order to ensure that the fields are
88 # iterated in the correct order when the class is created.
89 # This is only an issue in Python 3.5, where the order is
90 # random (and the wrong order causes the pool to refuse to add
91 # the descriptor because reasons).
92 entry_attrs = collections.OrderedDict(
93 {
94 "__module__": attrs.get("__module__", None),
95 "__qualname__": "{prefix}.{name}".format(
96 prefix=attrs.get("__qualname__", name),
97 name=msg_name,
98 ),
99 "_pb_options": {"map_entry": True},
100 }
101 )
102 entry_attrs["key"] = Field(field.map_key_type, number=1)
103 entry_attrs["value"] = Field(
104 field.proto_type,
105 number=2,
106 enum=field.enum,
107 message=field.message,
108 )
109 map_fields[msg_name] = MessageMeta(msg_name, (Message,), entry_attrs)
111 # Create the repeated field for the entry message.
112 map_fields[key] = RepeatedField(
113 ProtoType.MESSAGE,
114 number=field.number,
115 message=map_fields[msg_name],
116 )
118 # Add the new entries to the attrs
119 attrs.update(map_fields)
121 # Okay, now we deal with all the rest of the fields.
122 # Iterate over all the attributes and separate the fields into
123 # their own sequence.
124 fields = []
125 new_attrs = {}
126 oneofs = collections.OrderedDict()
127 proto_imports = set()
128 index = 0
129 for key, field in attrs.items():
130 # Sanity check: If this is not a field, do nothing.
131 if not isinstance(field, Field):
132 # The field objects themselves should not be direct attributes.
133 new_attrs[key] = field
134 continue
136 # Add data that the field requires that we do not take in the
137 # constructor because we can derive it from the metaclass.
138 # (The goal is to make the declaration syntax as nice as possible.)
139 field.mcls_data = {
140 "name": key,
141 "parent_name": full_name,
142 "index": index,
143 "package": package,
144 }
146 # Add the field to the list of fields.
147 fields.append(field)
148 # If this field is part of a "oneof", ensure the oneof itself
149 # is represented.
150 if field.oneof:
151 # Keep a running tally of the index of each oneof, and assign
152 # that index to the field's descriptor.
153 oneofs.setdefault(field.oneof, len(oneofs))
154 field.descriptor.oneof_index = oneofs[field.oneof]
156 # If this field references a message, it may be from another
157 # proto file; ensure we know about the import (to faithfully
158 # construct our file descriptor proto).
159 if field.message and not isinstance(field.message, str):
160 field_msg = field.message
161 if hasattr(field_msg, "pb") and callable(field_msg.pb):
162 field_msg = field_msg.pb()
163 # Sanity check: The field's message may not yet be defined if
164 # it was a Message defined in the same file, and the file
165 # descriptor proto has not yet been generated.
166 #
167 # We do nothing in this situation; everything will be handled
168 # correctly when the file descriptor is created later.
169 if field_msg:
170 proto_imports.add(field_msg.DESCRIPTOR.file.name)
172 # Same thing, but for enums.
173 elif field.enum and not isinstance(field.enum, str):
174 field_enum = (
175 field.enum._meta.pb
176 if hasattr(field.enum, "_meta")
177 else field.enum.DESCRIPTOR
178 )
180 if field_enum:
181 proto_imports.add(field_enum.file.name)
183 # Increment the field index counter.
184 index += 1
186 # As per descriptor.proto, all synthetic oneofs must be ordered after
187 # 'real' oneofs.
188 opt_attrs = {}
189 for field in fields:
190 if field.optional:
191 field.oneof = "_{}".format(field.name)
192 field.descriptor.oneof_index = oneofs[field.oneof] = len(oneofs)
193 opt_attrs[field.name] = field.name
195 # Generating a metaclass dynamically provides class attributes that
196 # instances can't see. This provides idiomatically named constants
197 # that enable the following pattern to check for field presence:
198 #
199 # class MyMessage(proto.Message):
200 # field = proto.Field(proto.INT32, number=1, optional=True)
201 #
202 # m = MyMessage()
203 # MyMessage.field in m
204 if opt_attrs:
205 mcls = type("AttrsMeta", (mcls,), opt_attrs)
207 # Determine the filename.
208 # We determine an appropriate proto filename based on the
209 # Python module.
210 filename = _file_info._FileInfo.proto_file_name(
211 new_attrs.get("__module__", name.lower())
212 )
214 # Get or create the information about the file, including the
215 # descriptor to which the new message descriptor shall be added.
216 file_info = _file_info._FileInfo.maybe_add_descriptor(filename, package)
218 # Ensure any imports that would be necessary are assigned to the file
219 # descriptor proto being created.
220 for proto_import in proto_imports:
221 if proto_import not in file_info.descriptor.dependency:
222 file_info.descriptor.dependency.append(proto_import)
224 # Retrieve any message options.
225 opts = descriptor_pb2.MessageOptions(**new_attrs.pop("_pb_options", {}))
227 # Create the underlying proto descriptor.
228 desc = descriptor_pb2.DescriptorProto(
229 name=name,
230 field=[i.descriptor for i in fields],
231 oneof_decl=[
232 descriptor_pb2.OneofDescriptorProto(name=i) for i in oneofs.keys()
233 ],
234 options=opts,
235 )
237 # If any descriptors were nested under this one, they need to be
238 # attached as nested types here.
239 child_paths = [p for p in file_info.nested.keys() if local_path == p[:-1]]
240 for child_path in child_paths:
241 desc.nested_type.add().MergeFrom(file_info.nested.pop(child_path))
243 # Same thing, but for enums
244 child_paths = [p for p in file_info.nested_enum.keys() if local_path == p[:-1]]
245 for child_path in child_paths:
246 desc.enum_type.add().MergeFrom(file_info.nested_enum.pop(child_path))
248 # Add the descriptor to the file if it is a top-level descriptor,
249 # or to a "holding area" for nested messages otherwise.
250 if len(local_path) == 1:
251 file_info.descriptor.message_type.add().MergeFrom(desc)
252 else:
253 file_info.nested[local_path] = desc
255 # Create the MessageInfo instance to be attached to this message.
256 new_attrs["_meta"] = _MessageInfo(
257 fields=fields,
258 full_name=full_name,
259 marshal=marshal,
260 options=opts,
261 package=package,
262 )
264 # Run the superclass constructor.
265 cls = super().__new__(mcls, name, bases, new_attrs)
267 # The info class and fields need a reference to the class just created.
268 cls._meta.parent = cls
269 for field in cls._meta.fields.values():
270 field.parent = cls
272 # Add this message to the _FileInfo instance; this allows us to
273 # associate the descriptor with the message once the descriptor
274 # is generated.
275 file_info.messages[full_name] = cls
277 # Generate the descriptor for the file if it is ready.
278 if file_info.ready(new_class=cls):
279 file_info.generate_file_pb(new_class=cls, fallback_salt=full_name)
281 # Done; return the class.
282 return cls
284 @classmethod
285 def __prepare__(mcls, name, bases, **kwargs):
286 return collections.OrderedDict()
288 @property
289 def meta(cls):
290 return cls._meta
292 def __dir__(self):
293 try:
294 names = set(dir(type))
295 names.update(
296 (
297 "meta",
298 "pb",
299 "wrap",
300 "serialize",
301 "deserialize",
302 "to_json",
303 "from_json",
304 "to_dict",
305 "copy_from",
306 )
307 )
308 desc = self.pb().DESCRIPTOR
309 names.update(t.name for t in desc.nested_types)
310 names.update(e.name for e in desc.enum_types)
312 return names
313 except AttributeError:
314 return dir(type)
316 def pb(cls, obj=None, *, coerce: bool = False):
317 """Return the underlying protobuf Message class or instance.
319 Args:
320 obj: If provided, and an instance of ``cls``, return the
321 underlying protobuf instance.
322 coerce (bool): If provided, will attempt to coerce ``obj`` to
323 ``cls`` if it is not already an instance.
324 """
325 if obj is None:
326 return cls.meta.pb
327 if not isinstance(obj, cls):
328 if coerce:
329 obj = cls(obj)
330 else:
331 raise TypeError(
332 "%r is not an instance of %s"
333 % (
334 obj,
335 cls.__name__,
336 )
337 )
338 return obj._pb
340 def wrap(cls, pb):
341 """Return a Message object that shallowly wraps the descriptor.
343 Args:
344 pb: A protocol buffer object, such as would be returned by
345 :meth:`pb`.
346 """
347 # Optimized fast path.
348 instance = cls.__new__(cls)
349 super(cls, instance).__setattr__("_pb", pb)
350 return instance
352 def serialize(cls, instance) -> bytes:
353 """Return the serialized proto.
355 Args:
356 instance: An instance of this message type, or something
357 compatible (accepted by the type's constructor).
359 Returns:
360 bytes: The serialized representation of the protocol buffer.
361 """
362 return cls.pb(instance, coerce=True).SerializeToString()
364 def deserialize(cls, payload: bytes) -> "Message":
365 """Given a serialized proto, deserialize it into a Message instance.
367 Args:
368 payload (bytes): The serialized proto.
370 Returns:
371 ~.Message: An instance of the message class against which this
372 method was called.
373 """
374 return cls.wrap(cls.pb().FromString(payload))
376 def _warn_if_including_default_value_fields_is_used_protobuf_5(
377 cls, including_default_value_fields: Optional[bool]
378 ) -> None:
379 """
380 Warn Protobuf 5.x+ users that `including_default_value_fields` is deprecated if it is set.
382 Args:
383 including_default_value_fields (Optional(bool)): The value of `including_default_value_fields` set by the user.
384 """
385 if (
386 PROTOBUF_VERSION[0] not in ("3", "4")
387 and including_default_value_fields is not None
388 ):
389 warnings.warn(
390 """The argument `including_default_value_fields` has been removed from
391 Protobuf 5.x. Please use `always_print_fields_with_no_presence` instead.
392 """,
393 DeprecationWarning,
394 )
396 def _raise_if_print_fields_values_are_set_and_differ(
397 cls,
398 always_print_fields_with_no_presence: Optional[bool],
399 including_default_value_fields: Optional[bool],
400 ) -> None:
401 """
402 Raise Exception if both `always_print_fields_with_no_presence` and `including_default_value_fields` are set
403 and the values differ.
405 Args:
406 always_print_fields_with_no_presence (Optional(bool)): The value of `always_print_fields_with_no_presence` set by the user.
407 including_default_value_fields (Optional(bool)): The value of `including_default_value_fields` set by the user.
408 Returns:
409 None
410 Raises:
411 ValueError: if both `always_print_fields_with_no_presence` and `including_default_value_fields` are set and
412 the values differ.
413 """
414 if (
415 always_print_fields_with_no_presence is not None
416 and including_default_value_fields is not None
417 and always_print_fields_with_no_presence != including_default_value_fields
418 ):
419 raise ValueError(
420 "Arguments `always_print_fields_with_no_presence` and `including_default_value_fields` must match"
421 )
423 def _normalize_print_fields_without_presence(
424 cls,
425 always_print_fields_with_no_presence: Optional[bool],
426 including_default_value_fields: Optional[bool],
427 ) -> bool:
428 """
429 Return true if fields with no presence should be included in the results.
430 By default, fields with no presence will be included in the results
431 when both `always_print_fields_with_no_presence` and
432 `including_default_value_fields` are not set
434 Args:
435 always_print_fields_with_no_presence (Optional(bool)): The value of `always_print_fields_with_no_presence` set by the user.
436 including_default_value_fields (Optional(bool)): The value of `including_default_value_fields` set by the user.
437 Returns:
438 None
439 Raises:
440 ValueError: if both `always_print_fields_with_no_presence` and `including_default_value_fields` are set and
441 the values differ.
442 """
444 cls._warn_if_including_default_value_fields_is_used_protobuf_5(
445 including_default_value_fields
446 )
447 cls._raise_if_print_fields_values_are_set_and_differ(
448 always_print_fields_with_no_presence, including_default_value_fields
449 )
450 # Default to True if neither `always_print_fields_with_no_presence` or `including_default_value_fields` is set
451 return (
452 (
453 always_print_fields_with_no_presence is None
454 and including_default_value_fields is None
455 )
456 or always_print_fields_with_no_presence
457 or including_default_value_fields
458 )
460 def to_json(
461 cls,
462 instance,
463 *,
464 use_integers_for_enums=True,
465 including_default_value_fields=None,
466 preserving_proto_field_name=False,
467 sort_keys=False,
468 indent=2,
469 float_precision=None,
470 always_print_fields_with_no_presence=None,
471 ) -> str:
472 """Given a message instance, serialize it to json
474 Args:
475 instance: An instance of this message type, or something
476 compatible (accepted by the type's constructor).
477 use_integers_for_enums (Optional(bool)): An option that determines whether enum
478 values should be represented by strings (False) or integers (True).
479 Default is True.
480 including_default_value_fields (Optional(bool)): Deprecated. Use argument
481 `always_print_fields_with_no_presence` instead. An option that
482 determines whether the default field values should be included in the results.
483 This value must match `always_print_fields_with_no_presence`,
484 if both arguments are explicitly set.
485 preserving_proto_field_name (Optional(bool)): An option that
486 determines whether field name representations preserve
487 proto case (snake_case) or use lowerCamelCase. Default is False.
488 sort_keys (Optional(bool)): If True, then the output will be sorted by field names.
489 Default is False.
490 indent (Optional(int)): The JSON object will be pretty-printed with this indent level.
491 An indent level of 0 or negative will only insert newlines.
492 Pass None for the most compact representation without newlines.
493 float_precision (Optional(int)): If set, use this to specify float field valid digits.
494 Default is None.
495 always_print_fields_with_no_presence (Optional(bool)): If True, fields without
496 presence (implicit presence scalars, repeated fields, and map fields) will
497 always be serialized. Any field that supports presence is not affected by
498 this option (including singular message fields and oneof fields).
499 This value must match `including_default_value_fields`,
500 if both arguments are explicitly set.
501 Returns:
502 str: The json string representation of the protocol buffer.
503 """
505 print_fields = cls._normalize_print_fields_without_presence(
506 always_print_fields_with_no_presence, including_default_value_fields
507 )
509 if PROTOBUF_VERSION[0] in ("3", "4"):
510 return MessageToJson(
511 cls.pb(instance),
512 use_integers_for_enums=use_integers_for_enums,
513 including_default_value_fields=print_fields,
514 preserving_proto_field_name=preserving_proto_field_name,
515 sort_keys=sort_keys,
516 indent=indent,
517 float_precision=float_precision,
518 )
519 else:
520 # The `including_default_value_fields` argument was removed from protobuf 5.x
521 # and replaced with `always_print_fields_with_no_presence` which very similar but has
522 # handles optional fields consistently by not affecting them.
523 # The old flag accidentally had inconsistent behavior between proto2
524 # optional and proto3 optional fields.
525 return MessageToJson(
526 cls.pb(instance),
527 use_integers_for_enums=use_integers_for_enums,
528 always_print_fields_with_no_presence=print_fields,
529 preserving_proto_field_name=preserving_proto_field_name,
530 sort_keys=sort_keys,
531 indent=indent,
532 float_precision=float_precision,
533 )
535 def from_json(cls, payload, *, ignore_unknown_fields=False) -> "Message":
536 """Given a json string representing an instance,
537 parse it into a message.
539 Args:
540 payload: A json string representing a message.
541 ignore_unknown_fields (Optional(bool)): If True, do not raise errors
542 for unknown fields.
544 Returns:
545 ~.Message: An instance of the message class against which this
546 method was called.
547 """
548 instance = cls()
549 Parse(payload, instance._pb, ignore_unknown_fields=ignore_unknown_fields)
550 return instance
552 def to_dict(
553 cls,
554 instance,
555 *,
556 use_integers_for_enums=True,
557 preserving_proto_field_name=True,
558 including_default_value_fields=None,
559 float_precision=None,
560 always_print_fields_with_no_presence=None,
561 ) -> Dict[str, Any]:
562 """Given a message instance, return its representation as a python dict.
564 Args:
565 instance: An instance of this message type, or something
566 compatible (accepted by the type's constructor).
567 use_integers_for_enums (Optional(bool)): An option that determines whether enum
568 values should be represented by strings (False) or integers (True).
569 Default is True.
570 preserving_proto_field_name (Optional(bool)): An option that
571 determines whether field name representations preserve
572 proto case (snake_case) or use lowerCamelCase. Default is True.
573 including_default_value_fields (Optional(bool)): Deprecated. Use argument
574 `always_print_fields_with_no_presence` instead. An option that
575 determines whether the default field values should be included in the results.
576 This value must match `always_print_fields_with_no_presence`,
577 if both arguments are explicitly set.
578 float_precision (Optional(int)): If set, use this to specify float field valid digits.
579 Default is None.
580 always_print_fields_with_no_presence (Optional(bool)): If True, fields without
581 presence (implicit presence scalars, repeated fields, and map fields) will
582 always be serialized. Any field that supports presence is not affected by
583 this option (including singular message fields and oneof fields). This value
584 must match `including_default_value_fields`, if both arguments are explicitly set.
586 Returns:
587 dict: A representation of the protocol buffer using pythonic data structures.
588 Messages and map fields are represented as dicts,
589 repeated fields are represented as lists.
590 """
592 print_fields = cls._normalize_print_fields_without_presence(
593 always_print_fields_with_no_presence, including_default_value_fields
594 )
596 if PROTOBUF_VERSION[0] in ("3", "4"):
597 return MessageToDict(
598 cls.pb(instance),
599 including_default_value_fields=print_fields,
600 preserving_proto_field_name=preserving_proto_field_name,
601 use_integers_for_enums=use_integers_for_enums,
602 float_precision=float_precision,
603 )
604 else:
605 # The `including_default_value_fields` argument was removed from protobuf 5.x
606 # and replaced with `always_print_fields_with_no_presence` which very similar but has
607 # handles optional fields consistently by not affecting them.
608 # The old flag accidentally had inconsistent behavior between proto2
609 # optional and proto3 optional fields.
610 return MessageToDict(
611 cls.pb(instance),
612 always_print_fields_with_no_presence=print_fields,
613 preserving_proto_field_name=preserving_proto_field_name,
614 use_integers_for_enums=use_integers_for_enums,
615 float_precision=float_precision,
616 )
618 def copy_from(cls, instance, other):
619 """Equivalent for protobuf.Message.CopyFrom
621 Args:
622 instance: An instance of this message type
623 other: (Union[dict, ~.Message):
624 A dictionary or message to reinitialize the values for this message.
625 """
626 if isinstance(other, cls):
627 # Just want the underlying proto.
628 other = Message.pb(other)
629 elif isinstance(other, cls.pb()):
630 # Don't need to do anything.
631 pass
632 elif isinstance(other, collections.abc.Mapping):
633 # Coerce into a proto
634 other = cls._meta.pb(**other)
635 else:
636 raise TypeError(
637 "invalid argument type to copy to {}: {}".format(
638 cls.__name__, other.__class__.__name__
639 )
640 )
642 # Note: we can't just run self.__init__ because this may be a message field
643 # for a higher order proto; the memory layout for protos is NOT LIKE the
644 # python memory model. We cannot rely on just setting things by reference.
645 # Non-trivial complexity is (partially) hidden by the protobuf runtime.
646 cls.pb(instance).CopyFrom(other)
649class Message(metaclass=MessageMeta):
650 """The abstract base class for a message.
652 Args:
653 mapping (Union[dict, ~.Message]): A dictionary or message to be
654 used to determine the values for this message.
655 ignore_unknown_fields (Optional(bool)): If True, do not raise errors for
656 unknown fields. Only applied if `mapping` is a mapping type or there
657 are keyword parameters.
658 kwargs (dict): Keys and values corresponding to the fields of the
659 message.
660 """
662 def __init__(
663 self,
664 mapping=None,
665 *,
666 ignore_unknown_fields=False,
667 **kwargs,
668 ):
669 # We accept several things for `mapping`:
670 # * An instance of this class.
671 # * An instance of the underlying protobuf descriptor class.
672 # * A dict
673 # * Nothing (keyword arguments only).
674 if mapping is None:
675 if not kwargs:
676 # Special fast path for empty construction.
677 super().__setattr__("_pb", self._meta.pb())
678 return
680 mapping = kwargs
681 elif isinstance(mapping, self._meta.pb):
682 # Make a copy of the mapping.
683 # This is a constructor for a new object, so users will assume
684 # that it will not have side effects on the arguments being
685 # passed in.
686 #
687 # The `wrap` method on the metaclass is the public API for taking
688 # ownership of the passed in protobuf object.
689 mapping = copy.deepcopy(mapping)
690 if kwargs:
691 mapping.MergeFrom(self._meta.pb(**kwargs))
693 super().__setattr__("_pb", mapping)
694 return
695 elif isinstance(mapping, type(self)):
696 # Just use the above logic on mapping's underlying pb.
697 self.__init__(mapping=mapping._pb, **kwargs)
698 return
699 elif isinstance(mapping, collections.abc.Mapping):
700 # Can't have side effects on mapping.
701 mapping = copy.copy(mapping)
702 # kwargs entries take priority for duplicate keys.
703 mapping.update(kwargs)
704 else:
705 # Sanity check: Did we get something not a map? Error if so.
706 raise TypeError(
707 "Invalid constructor input for %s: %r"
708 % (
709 self.__class__.__name__,
710 mapping,
711 )
712 )
714 params = {}
715 # Update the mapping to address any values that need to be
716 # coerced.
717 marshal = self._meta.marshal
718 for key, value in mapping.items():
719 (key, pb_type) = self._get_pb_type_from_key(key)
720 if pb_type is None:
721 if ignore_unknown_fields:
722 continue
724 raise ValueError(
725 "Unknown field for {}: {}".format(self.__class__.__name__, key)
726 )
728 pb_value = marshal.to_proto(pb_type, value)
730 if pb_value is not None:
731 params[key] = pb_value
733 # Create the internal protocol buffer.
734 super().__setattr__("_pb", self._meta.pb(**params))
736 def _get_pb_type_from_key(self, key):
737 """Given a key, return the corresponding pb_type.
739 Args:
740 key(str): The name of the field.
742 Returns:
743 A tuple containing a key and pb_type. The pb_type will be
744 the composite type of the field, or the primitive type if a primitive.
745 If no corresponding field exists, return None.
746 """
748 pb_type = None
750 try:
751 pb_type = self._meta.fields[key].pb_type
752 except KeyError:
753 # Underscores may be appended to field names
754 # that collide with python or proto-plus keywords.
755 # In case a key only exists with a `_` suffix, coerce the key
756 # to include the `_` suffix. It's not possible to
757 # natively define the same field with a trailing underscore in protobuf.
758 # See related issue
759 # https://github.com/googleapis/python-api-core/issues/227
760 if f"{key}_" in self._meta.fields:
761 key = f"{key}_"
762 pb_type = self._meta.fields[key].pb_type
764 return (key, pb_type)
766 def __dir__(self):
767 desc = type(self).pb().DESCRIPTOR
768 names = {f_name for f_name in self._meta.fields.keys()}
769 names.update(m.name for m in desc.nested_types)
770 names.update(e.name for e in desc.enum_types)
771 names.update(dir(object()))
772 # Can't think of a better way of determining
773 # the special methods than manually listing them.
774 names.update(
775 (
776 "__bool__",
777 "__contains__",
778 "__dict__",
779 "__getattr__",
780 "__getstate__",
781 "__module__",
782 "__setstate__",
783 "__weakref__",
784 )
785 )
787 return names
789 def __bool__(self):
790 """Return True if any field is truthy, False otherwise."""
791 return any(k in self and getattr(self, k) for k in self._meta.fields.keys())
793 def __contains__(self, key):
794 """Return True if this field was set to something non-zero on the wire.
796 In most cases, this method will return True when ``__getattr__``
797 would return a truthy value and False when it would return a falsy
798 value, so explicitly calling this is not useful.
800 The exception case is empty messages explicitly set on the wire,
801 which are falsy from ``__getattr__``. This method allows to
802 distinguish between an explicitly provided empty message and the
803 absence of that message, which is useful in some edge cases.
805 The most common edge case is the use of ``google.protobuf.BoolValue``
806 to get a boolean that distinguishes between ``False`` and ``None``
807 (or the same for a string, int, etc.). This library transparently
808 handles that case for you, but this method remains available to
809 accommodate cases not automatically covered.
811 Args:
812 key (str): The name of the field.
814 Returns:
815 bool: Whether the field's value corresponds to a non-empty
816 wire serialization.
817 """
818 pb_value = getattr(self._pb, key)
819 try:
820 # Protocol buffers "HasField" is unfriendly; it only works
821 # against composite, non-repeated fields, and raises ValueError
822 # against any repeated field or primitive.
823 #
824 # There is no good way to test whether it is valid to provide
825 # a field to this method, so sadly we are stuck with a
826 # somewhat inefficient try/except.
827 return self._pb.HasField(key)
828 except ValueError:
829 return bool(pb_value)
831 def __delattr__(self, key):
832 """Delete the value on the given field.
834 This is generally equivalent to setting a falsy value.
835 """
836 self._pb.ClearField(key)
838 def __eq__(self, other):
839 """Return True if the messages are equal, False otherwise."""
840 # If these are the same type, use internal protobuf's equality check.
841 if isinstance(other, type(self)):
842 return self._pb == other._pb
844 # If the other type is the target protobuf object, honor that also.
845 if isinstance(other, self._meta.pb):
846 return self._pb == other
848 # Ask the other object.
849 return NotImplemented
851 def __getattr__(self, key):
852 """Retrieve the given field's value.
854 In protocol buffers, the presence of a field on a message is
855 sufficient for it to always be "present".
857 For primitives, a value of the correct type will always be returned
858 (the "falsy" values in protocol buffers consistently match those
859 in Python). For repeated fields, the falsy value is always an empty
860 sequence.
862 For messages, protocol buffers does distinguish between an empty
863 message and absence, but this distinction is subtle and rarely
864 relevant. Therefore, this method always returns an empty message
865 (following the official implementation). To check for message
866 presence, use ``key in self`` (in other words, ``__contains__``).
868 .. note::
870 Some well-known protocol buffer types
871 (e.g. ``google.protobuf.Timestamp``) will be converted to
872 their Python equivalents. See the ``marshal`` module for
873 more details.
874 """
875 (key, pb_type) = self._get_pb_type_from_key(key)
876 if pb_type is None:
877 raise AttributeError(
878 "Unknown field for {}: {}".format(self.__class__.__name__, key)
879 )
880 pb_value = getattr(self._pb, key)
881 marshal = self._meta.marshal
882 return marshal.to_python(pb_type, pb_value, absent=key not in self)
884 def __ne__(self, other):
885 """Return True if the messages are unequal, False otherwise."""
886 return not self == other
888 def __repr__(self):
889 return repr(self._pb)
891 def __setattr__(self, key, value):
892 """Set the value on the given field.
894 For well-known protocol buffer types which are marshalled, either
895 the protocol buffer object or the Python equivalent is accepted.
896 """
897 if key[0] == "_":
898 return super().__setattr__(key, value)
899 marshal = self._meta.marshal
900 (key, pb_type) = self._get_pb_type_from_key(key)
901 if pb_type is None:
902 raise AttributeError(
903 "Unknown field for {}: {}".format(self.__class__.__name__, key)
904 )
906 pb_value = marshal.to_proto(pb_type, value)
908 # Clear the existing field.
909 # This is the only way to successfully write nested falsy values,
910 # because otherwise MergeFrom will no-op on them.
911 self._pb.ClearField(key)
913 # Merge in the value being set.
914 if pb_value is not None:
915 self._pb.MergeFrom(self._meta.pb(**{key: pb_value}))
917 def __getstate__(self):
918 """Serialize for pickling."""
919 return self._pb.SerializeToString()
921 def __setstate__(self, value):
922 """Deserialization for pickling."""
923 new_pb = self._meta.pb().FromString(value)
924 super().__setattr__("_pb", new_pb)
927class _MessageInfo:
928 """Metadata about a message.
930 Args:
931 fields (Tuple[~.fields.Field]): The fields declared on the message.
932 package (str): The proto package.
933 full_name (str): The full name of the message.
934 file_info (~._FileInfo): The file descriptor and messages for the
935 file containing this message.
936 marshal (~.Marshal): The marshal instance to which this message was
937 automatically registered.
938 options (~.descriptor_pb2.MessageOptions): Any options that were
939 set on the message.
940 """
942 def __init__(
943 self,
944 *,
945 fields: List[Field],
946 package: str,
947 full_name: str,
948 marshal: Marshal,
949 options: descriptor_pb2.MessageOptions,
950 ) -> None:
951 self.package = package
952 self.full_name = full_name
953 self.options = options
954 self.fields = collections.OrderedDict((i.name, i) for i in fields)
955 self.fields_by_number = collections.OrderedDict((i.number, i) for i in fields)
956 self.marshal = marshal
957 self._pb = None
959 @property
960 def pb(self) -> Type[message.Message]:
961 """Return the protobuf message type for this descriptor.
963 If a field on the message references another message which has not
964 loaded, then this method returns None.
965 """
966 return self._pb
969__all__ = ("Message",)