Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/sqlalchemy/engine/characteristics.py: 84%

1# engine/characteristics.py 

2# Copyright (C) 2005-2024 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 

7import abc 

8 

9from ..util import ABC 

10 

11 

12class ConnectionCharacteristic(ABC): 

13 """An abstract base for an object that can set, get and reset a 

14 per-connection characteristic, typically one that gets reset when the 

15 connection is returned to the connection pool. 

16 

17 transaction isolation is the canonical example, and the 

18 ``IsolationLevelCharacteristic`` implementation provides this for the 

19 ``DefaultDialect``. 

20 

21 The ``ConnectionCharacteristic`` class should call upon the ``Dialect`` for 

22 the implementation of each method. The object exists strictly to serve as 

23 a dialect visitor that can be placed into the 

24 ``DefaultDialect.connection_characteristics`` dictionary where it will take 

25 effect for calls to :meth:`_engine.Connection.execution_options` and 

26 related APIs. 

27 

28 .. versionadded:: 1.4 

29 

30 """ 

31 

32 __slots__ = () 

33 

34 transactional = False 

35 

36 @abc.abstractmethod 

37 def reset_characteristic(self, dialect, dbapi_conn): 

38 """Reset the characteristic on the connection to its default value.""" 

39 

40 @abc.abstractmethod 

41 def set_characteristic(self, dialect, dbapi_conn, value): 

42 """set characteristic on the connection to a given value.""" 

43 

44 @abc.abstractmethod 

45 def get_characteristic(self, dialect, dbapi_conn): 

46 """Given a DBAPI connection, get the current value of the 

47 characteristic. 

48 

49 """ 

50 

51 

52class IsolationLevelCharacteristic(ConnectionCharacteristic): 

53 transactional = True 

54 

55 def reset_characteristic(self, dialect, dbapi_conn): 

56 dialect.reset_isolation_level(dbapi_conn) 

57 

58 def set_characteristic(self, dialect, dbapi_conn, value): 

59 dialect.set_isolation_level(dbapi_conn, value) 

60 

61 def get_characteristic(self, dialect, dbapi_conn): 

62 return dialect.get_isolation_level(dbapi_conn)