sqlalchemy.engine.events.ConnectionEvents

Intercept low-level cursor execute() events after execution. :param conn: :class:`_engine.Connection` object :param cursor: DBAPI cursor object. Will have results pending if the statement was a SELECT, but these should not be consumed as they will be needed by the :class:`_engine.CursorResult`. :param statement: string SQL statement, as passed to the DBAPI :param parameters: Dictionary, tuple, or list of parameters being passed to the ``execute()`` or ``executemany()`` method of the DBAPI ``cursor``. In some cases may be ``None``. :param context: :class:`.ExecutionContext` object in use. May be ``None``. :param executemany: boolean, if ``True``, this is an ``executemany()`` call, if ``False``, this is an ``execute()`` call.

Intercept high level execute() events after execute. :param conn: :class:`_engine.Connection` object :param clauseelement: SQL expression construct, :class:`.Compiled` instance, or string statement passed to :meth:`_engine.Connection.execute`. :param multiparams: Multiple parameter sets, a list of dictionaries. :param params: Single parameter set, a single dictionary. :param execution_options: dictionary of execution options passed along with the statement, if any. This is a merge of all options that will be used, including those of the statement, the connection, and those passed in to the method itself for the 2.0 style of execution. .. versionadded: 1.4 :param result: :class:`_engine.CursorResult` generated by the execution.

Intercept low-level cursor execute() events before execution, receiving the string SQL statement and DBAPI-specific parameter list to be invoked against a cursor. This event is a good choice for logging as well as late modifications to the SQL string. It's less ideal for parameter modifications except for those which are specific to a target backend. This event can be optionally established with the ``retval=True`` flag. The ``statement`` and ``parameters`` arguments should be returned as a two-tuple in this case:: @event.listens_for(Engine, "before_cursor_execute", retval=True) def before_cursor_execute(conn, cursor, statement, parameters, context, executemany): # do something with statement, parameters return statement, parameters See the example at :class:`_events.ConnectionEvents`. :param conn: :class:`_engine.Connection` object :param cursor: DBAPI cursor object :param statement: string SQL statement, as to be passed to the DBAPI :param parameters: Dictionary, tuple, or list of parameters being passed to the ``execute()`` or ``executemany()`` method of the DBAPI ``cursor``. In some cases may be ``None``. :param context: :class:`.ExecutionContext` object in use. May be ``None``. :param executemany: boolean, if ``True``, this is an ``executemany()`` call, if ``False``, this is an ``execute()`` call. .. seealso:: :meth:`.before_execute` :meth:`.after_cursor_execute`

Intercept high level execute() events, receiving uncompiled SQL constructs and other objects prior to rendering into SQL. This event is good for debugging SQL compilation issues as well as early manipulation of the parameters being sent to the database, as the parameter lists will be in a consistent format here. This event can be optionally established with the ``retval=True`` flag. The ``clauseelement``, ``multiparams``, and ``params`` arguments should be returned as a three-tuple in this case:: @event.listens_for(Engine, "before_execute", retval=True) def before_execute(conn, clauseelement, multiparams, params): # do something with clauseelement, multiparams, params return clauseelement, multiparams, params :param conn: :class:`_engine.Connection` object :param clauseelement: SQL expression construct, :class:`.Compiled` instance, or string statement passed to :meth:`_engine.Connection.execute`. :param multiparams: Multiple parameter sets, a list of dictionaries. :param params: Single parameter set, a single dictionary. :param execution_options: dictionary of execution options passed along with the statement, if any. This is a merge of all options that will be used, including those of the statement, the connection, and those passed in to the method itself for the 2.0 style of execution. .. versionadded: 1.4 .. seealso:: :meth:`.before_cursor_execute`

Intercept begin() events. :param conn: :class:`_engine.Connection` object

Intercept begin_twophase() events. :param conn: :class:`_engine.Connection` object :param xid: two-phase XID identifier

Intercept commit() events, as initiated by a :class:`.Transaction`. Note that the :class:`_pool.Pool` may also "auto-commit" a DBAPI connection upon checkin, if the ``reset_on_return`` flag is set to the value ``'commit'``. To intercept this commit, use the :meth:`_events.PoolEvents.reset` hook. :param conn: :class:`_engine.Connection` object

Intercept commit_twophase() events. :param conn: :class:`_engine.Connection` object :param xid: two-phase XID identifier :param is_prepared: boolean, indicates if :meth:`.TwoPhaseTransaction.prepare` was called.

Intercept the creation of a new :class:`_engine.Connection`. This event is called typically as the direct result of calling the :meth:`_engine.Engine.connect` method. It differs from the :meth:`_events.PoolEvents.connect` method, which refers to the actual connection to a database at the DBAPI level; a DBAPI connection may be pooled and reused for many operations. In contrast, this event refers only to the production of a higher level :class:`_engine.Connection` wrapper around such a DBAPI connection. It also differs from the :meth:`_events.PoolEvents.checkout` event in that it is specific to the :class:`_engine.Connection` object, not the DBAPI connection that :meth:`_events.PoolEvents.checkout` deals with, although this DBAPI connection is available here via the :attr:`_engine.Connection.connection` attribute. But note there can in fact be multiple :meth:`_events.PoolEvents.checkout` events within the lifespan of a single :class:`_engine.Connection` object, if that :class:`_engine.Connection` is invalidated and re-established. :param conn: :class:`_engine.Connection` object. .. seealso:: :meth:`_events.PoolEvents.checkout` the lower-level pool checkout event for an individual DBAPI connection

Intercept when the :meth:`_engine.Engine.dispose` method is called. The :meth:`_engine.Engine.dispose` method instructs the engine to "dispose" of it's connection pool (e.g. :class:`_pool.Pool`), and replaces it with a new one. Disposing of the old pool has the effect that existing checked-in connections are closed. The new pool does not establish any new connections until it is first used. This event can be used to indicate that resources related to the :class:`_engine.Engine` should also be cleaned up, keeping in mind that the :class:`_engine.Engine` can still be used for new requests in which case it re-acquires connection resources. .. versionadded:: 1.0.5

Intercept prepare_twophase() events. :param conn: :class:`_engine.Connection` object :param xid: two-phase XID identifier

Intercept release_savepoint() events. :param conn: :class:`_engine.Connection` object :param name: specified name used for the savepoint. :param context: not used

Intercept rollback() events, as initiated by a :class:`.Transaction`. Note that the :class:`_pool.Pool` also "auto-rolls back" a DBAPI connection upon checkin, if the ``reset_on_return`` flag is set to its default value of ``'rollback'``. To intercept this rollback, use the :meth:`_events.PoolEvents.reset` hook. :param conn: :class:`_engine.Connection` object .. seealso:: :meth:`_events.PoolEvents.reset`

Intercept rollback_savepoint() events. :param conn: :class:`_engine.Connection` object :param name: specified name used for the savepoint. :param context: not used

Intercept rollback_twophase() events. :param conn: :class:`_engine.Connection` object :param xid: two-phase XID identifier :param is_prepared: boolean, indicates if :meth:`.TwoPhaseTransaction.prepare` was called.

Intercept savepoint() events. :param conn: :class:`_engine.Connection` object :param name: specified name used for the savepoint.

Intercept when the :meth:`_engine.Connection.execution_options` method is called. This method is called after the new :class:`_engine.Connection` has been produced, with the newly updated execution options collection, but before the :class:`.Dialect` has acted upon any of those new options. Note that this method is not called when a new :class:`_engine.Connection` is produced which is inheriting execution options from its parent :class:`_engine.Engine`; to intercept this condition, use the :meth:`_events.ConnectionEvents.engine_connect` event. :param conn: The newly copied :class:`_engine.Connection` object :param opts: dictionary of options that were passed to the :meth:`_engine.Connection.execution_options` method. This dictionary may be modified in place to affect the ultimate options which take effect. .. versionadded:: 2.0 the ``opts`` dictionary may be modified in place. .. seealso:: :meth:`_events.ConnectionEvents.set_engine_execution_options` - event which is called when :meth:`_engine.Engine.execution_options` is called.

Intercept when the :meth:`_engine.Engine.execution_options` method is called. The :meth:`_engine.Engine.execution_options` method produces a shallow copy of the :class:`_engine.Engine` which stores the new options. That new :class:`_engine.Engine` is passed here. A particular application of this method is to add a :meth:`_events.ConnectionEvents.engine_connect` event handler to the given :class:`_engine.Engine` which will perform some per- :class:`_engine.Connection` task specific to these execution options. :param conn: The newly copied :class:`_engine.Engine` object :param opts: dictionary of options that were passed to the :meth:`_engine.Connection.execution_options` method. This dictionary may be modified in place to affect the ultimate options which take effect. .. versionadded:: 2.0 the ``opts`` dictionary may be modified in place. .. seealso:: :meth:`_events.ConnectionEvents.set_connection_execution_options` - event which is called when :meth:`_engine.Connection.execution_options` is called.