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# engine/events.py # Copyright (C) 2005-2024 the SQLAlchemy authors and contributors # <see AUTHORS file> # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php from __future__ import annotations import typing from typing import Any from typing import Dict from typing import Optional from typing import Tuple from typing import Type from typing import Union from .base import Connection from .base import Engine from .interfaces import ConnectionEventsTarget from .interfaces import DBAPIConnection from .interfaces import DBAPICursor from .interfaces import Dialect from .. import event from .. import exc from ..util.typing import Literal if typing.TYPE_CHECKING: from .interfaces import _CoreMultiExecuteParams from .interfaces import _CoreSingleExecuteParams from .interfaces import _DBAPIAnyExecuteParams from .interfaces import _DBAPIMultiExecuteParams from .interfaces import _DBAPISingleExecuteParams from .interfaces import _ExecuteOptions from .interfaces import ExceptionContext from .interfaces import ExecutionContext from .result import Result from ..pool import ConnectionPoolEntry from ..sql import Executable from ..sql.elements import BindParameter class ConnectionEvents(event.Events[ConnectionEventsTarget]): """Available events for :class:`_engine.Connection` and :class:`_engine.Engine`. The methods here define the name of an event as well as the names of members that are passed to listener functions. An event listener can be associated with any :class:`_engine.Connection` or :class:`_engine.Engine` class or instance, such as an :class:`_engine.Engine`, e.g.:: from sqlalchemy import event, create_engine def before_cursor_execute(conn, cursor, statement, parameters, context, executemany): log.info("Received statement: %s", statement) engine = create_engine('postgresql+psycopg2://scott:tiger@localhost/test') event.listen(engine, "before_cursor_execute", before_cursor_execute) or with a specific :class:`_engine.Connection`:: with engine.begin() as conn: @event.listens_for(conn, 'before_cursor_execute') def before_cursor_execute(conn, cursor, statement, parameters, context, executemany): log.info("Received statement: %s", statement) When the methods are called with a `statement` parameter, such as in :meth:`.after_cursor_execute` or :meth:`.before_cursor_execute`, the statement is the exact SQL string that was prepared for transmission to the DBAPI ``cursor`` in the connection's :class:`.Dialect`. The :meth:`.before_execute` and :meth:`.before_cursor_execute` events can also be established with the ``retval=True`` flag, which allows modification of the statement and parameters to be sent to the database. The :meth:`.before_cursor_execute` event is particularly useful here to add ad-hoc string transformations, such as comments, to all executions:: from sqlalchemy.engine import Engine from sqlalchemy import event @event.listens_for(Engine, "before_cursor_execute", retval=True) def comment_sql_calls(conn, cursor, statement, parameters, context, executemany): statement = statement + " -- some comment" return statement, parameters .. note:: :class:`_events.ConnectionEvents` can be established on any combination of :class:`_engine.Engine`, :class:`_engine.Connection`, as well as instances of each of those classes. Events across all four scopes will fire off for a given instance of :class:`_engine.Connection`. However, for performance reasons, the :class:`_engine.Connection` object determines at instantiation time whether or not its parent :class:`_engine.Engine` has event listeners established. Event listeners added to the :class:`_engine.Engine` class or to an instance of :class:`_engine.Engine` *after* the instantiation of a dependent :class:`_engine.Connection` instance will usually *not* be available on that :class:`_engine.Connection` instance. The newly added listeners will instead take effect for :class:`_engine.Connection` instances created subsequent to those event listeners being established on the parent :class:`_engine.Engine` class or instance. :param retval=False: Applies to the :meth:`.before_execute` and :meth:`.before_cursor_execute` events only. When True, the user-defined event function must have a return value, which is a tuple of parameters that replace the given statement and parameters. See those methods for a description of specific return arguments. """ # noqa _target_class_doc = "SomeEngine" _dispatch_target = ConnectionEventsTarget @classmethod def _accept_with( cls, target: Union[ConnectionEventsTarget, Type[ConnectionEventsTarget]], identifier: str, ) -> Optional[Union[ConnectionEventsTarget, Type[ConnectionEventsTarget]]]: default_dispatch = super()._accept_with(target, identifier) if default_dispatch is None and hasattr( target, "_no_async_engine_events" ): target._no_async_engine_events() return default_dispatch @classmethod def _listen( cls, event_key: event._EventKey[ConnectionEventsTarget], *, retval: bool = False, **kw: Any, ) -> None: target, identifier, fn = ( event_key.dispatch_target, event_key.identifier, event_key._listen_fn, ) target._has_events = True if not retval: if identifier == "before_execute": orig_fn = fn def wrap_before_execute( # type: ignore conn, clauseelement, multiparams, params, execution_options ): orig_fn( conn, clauseelement, multiparams, params, execution_options, ) return clauseelement, multiparams, params fn = wrap_before_execute elif identifier == "before_cursor_execute": orig_fn = fn def wrap_before_cursor_execute( # type: ignore conn, cursor, statement, parameters, context, executemany ): orig_fn( conn, cursor, statement, parameters, context, executemany, ) return statement, parameters fn = wrap_before_cursor_execute elif retval and identifier not in ( "before_execute", "before_cursor_execute", ): raise exc.ArgumentError( "Only the 'before_execute', " "'before_cursor_execute' and 'handle_error' engine " "event listeners accept the 'retval=True' " "argument." ) event_key.with_wrapper(fn).base_listen() @event._legacy_signature( "1.4", ["conn", "clauseelement", "multiparams", "params"], lambda conn, clauseelement, multiparams, params, execution_options: ( conn, clauseelement, multiparams, params, ), ) def before_execute( self, conn: Connection, clauseelement: Executable, multiparams: _CoreMultiExecuteParams, params: _CoreSingleExecuteParams, execution_options: _ExecuteOptions, ) -> Optional[ Tuple[Executable, _CoreMultiExecuteParams, _CoreSingleExecuteParams] ]: """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` """ @event._legacy_signature( "1.4", ["conn", "clauseelement", "multiparams", "params", "result"], lambda conn, clauseelement, multiparams, params, execution_options, result: ( # noqa conn, clauseelement, multiparams, params, result, ), ) def after_execute( self, conn: Connection, clauseelement: Executable, multiparams: _CoreMultiExecuteParams, params: _CoreSingleExecuteParams, execution_options: _ExecuteOptions, result: Result[Any], ) -> None: """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. """ def before_cursor_execute( self, conn: Connection, cursor: DBAPICursor, statement: str, parameters: _DBAPIAnyExecuteParams, context: Optional[ExecutionContext], executemany: bool, ) -> Optional[Tuple[str, _DBAPIAnyExecuteParams]]: """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` """ def after_cursor_execute( self, conn: Connection, cursor: DBAPICursor, statement: str, parameters: _DBAPIAnyExecuteParams, context: Optional[ExecutionContext], executemany: bool, ) -> None: """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. """ @event._legacy_signature( "2.0", ["conn", "branch"], converter=lambda conn: (conn, False) ) def engine_connect(self, conn: Connection) -> None: """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 """ def set_connection_execution_options( self, conn: Connection, opts: Dict[str, Any] ) -> None: """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. """ def set_engine_execution_options( self, engine: Engine, opts: Dict[str, Any] ) -> None: """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. """ def engine_disposed(self, engine: Engine) -> None: """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. """ def begin(self, conn: Connection) -> None: """Intercept begin() events. :param conn: :class:`_engine.Connection` object """ def rollback(self, conn: Connection) -> None: """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` """ def commit(self, conn: Connection) -> None: """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 """ def savepoint(self, conn: Connection, name: str) -> None: """Intercept savepoint() events. :param conn: :class:`_engine.Connection` object :param name: specified name used for the savepoint. """ def rollback_savepoint( self, conn: Connection, name: str, context: None ) -> None: """Intercept rollback_savepoint() events. :param conn: :class:`_engine.Connection` object :param name: specified name used for the savepoint. :param context: not used """ # TODO: deprecate "context" def release_savepoint( self, conn: Connection, name: str, context: None ) -> None: """Intercept release_savepoint() events. :param conn: :class:`_engine.Connection` object :param name: specified name used for the savepoint. :param context: not used """ # TODO: deprecate "context" def begin_twophase(self, conn: Connection, xid: Any) -> None: """Intercept begin_twophase() events. :param conn: :class:`_engine.Connection` object :param xid: two-phase XID identifier """ def prepare_twophase(self, conn: Connection, xid: Any) -> None: """Intercept prepare_twophase() events. :param conn: :class:`_engine.Connection` object :param xid: two-phase XID identifier """ def rollback_twophase( self, conn: Connection, xid: Any, is_prepared: bool ) -> None: """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. """ def commit_twophase( self, conn: Connection, xid: Any, is_prepared: bool ) -> None: """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. """ class DialectEvents(event.Events[Dialect]): """event interface for execution-replacement functions. These events allow direct instrumentation and replacement of key dialect functions which interact with the DBAPI. .. note:: :class:`.DialectEvents` hooks should be considered **semi-public** and experimental. These hooks are not for general use and are only for those situations where intricate re-statement of DBAPI mechanics must be injected onto an existing dialect. For general-use statement-interception events, please use the :class:`_events.ConnectionEvents` interface. .. seealso:: :meth:`_events.ConnectionEvents.before_cursor_execute` :meth:`_events.ConnectionEvents.before_execute` :meth:`_events.ConnectionEvents.after_cursor_execute` :meth:`_events.ConnectionEvents.after_execute` """ _target_class_doc = "SomeEngine" _dispatch_target = Dialect @classmethod def _listen( cls, event_key: event._EventKey[Dialect], *, retval: bool = False, **kw: Any, ) -> None: target = event_key.dispatch_target target._has_events = True event_key.base_listen() @classmethod def _accept_with( cls, target: Union[Engine, Type[Engine], Dialect, Type[Dialect]], identifier: str, ) -> Optional[Union[Dialect, Type[Dialect]]]: if isinstance(target, type): if issubclass(target, Engine): return Dialect elif issubclass(target, Dialect): return target elif isinstance(target, Engine): return target.dialect elif isinstance(target, Dialect): return target elif isinstance(target, Connection) and identifier == "handle_error": raise exc.InvalidRequestError( "The handle_error() event hook as of SQLAlchemy 2.0 is " "established on the Dialect, and may only be applied to the " "Engine as a whole or to a specific Dialect as a whole, " "not on a per-Connection basis." ) elif hasattr(target, "_no_async_engine_events"): target._no_async_engine_events() else: return None def handle_error( self, exception_context: ExceptionContext ) -> Optional[BaseException]: r"""Intercept all exceptions processed by the :class:`_engine.Dialect`, typically but not limited to those emitted within the scope of a :class:`_engine.Connection`. .. versionchanged:: 2.0 the :meth:`.DialectEvents.handle_error` event is moved to the :class:`.DialectEvents` class, moved from the :class:`.ConnectionEvents` class, so that it may also participate in the "pre ping" operation configured with the :paramref:`_sa.create_engine.pool_pre_ping` parameter. The event remains registered by using the :class:`_engine.Engine` as the event target, however note that using the :class:`_engine.Connection` as an event target for :meth:`.DialectEvents.handle_error` is no longer supported. This includes all exceptions emitted by the DBAPI as well as within SQLAlchemy's statement invocation process, including encoding errors and other statement validation errors. Other areas in which the event is invoked include transaction begin and end, result row fetching, cursor creation. Note that :meth:`.handle_error` may support new kinds of exceptions and new calling scenarios at *any time*. Code which uses this event must expect new calling patterns to be present in minor releases. To support the wide variety of members that correspond to an exception, as well as to allow extensibility of the event without backwards incompatibility, the sole argument received is an instance of :class:`.ExceptionContext`. This object contains data members representing detail about the exception. Use cases supported by this hook include: * read-only, low-level exception handling for logging and debugging purposes * Establishing whether a DBAPI connection error message indicates that the database connection needs to be reconnected, including for the "pre_ping" handler used by **some** dialects * Establishing or disabling whether a connection or the owning connection pool is invalidated or expired in response to a specific exception * exception re-writing The hook is called while the cursor from the failed operation (if any) is still open and accessible. Special cleanup operations can be called on this cursor; SQLAlchemy will attempt to close this cursor subsequent to this hook being invoked. As of SQLAlchemy 2.0, the "pre_ping" handler enabled using the :paramref:`_sa.create_engine.pool_pre_ping` parameter will also participate in the :meth:`.handle_error` process, **for those dialects that rely upon disconnect codes to detect database liveness**. Note that some dialects such as psycopg, psycopg2, and most MySQL dialects make use of a native ``ping()`` method supplied by the DBAPI which does not make use of disconnect codes. .. versionchanged:: 2.0.0 The :meth:`.DialectEvents.handle_error` event hook participates in connection pool "pre-ping" operations. Within this usage, the :attr:`.ExceptionContext.engine` attribute will be ``None``, however the :class:`.Dialect` in use is always available via the :attr:`.ExceptionContext.dialect` attribute. .. versionchanged:: 2.0.5 Added :attr:`.ExceptionContext.is_pre_ping` attribute which will be set to ``True`` when the :meth:`.DialectEvents.handle_error` event hook is triggered within a connection pool pre-ping operation. .. versionchanged:: 2.0.5 An issue was repaired that allows for the PostgreSQL ``psycopg`` and ``psycopg2`` drivers, as well as all MySQL drivers, to properly participate in the :meth:`.DialectEvents.handle_error` event hook during connection pool "pre-ping" operations; previously, the implementation was non-working for these drivers. A handler function has two options for replacing the SQLAlchemy-constructed exception into one that is user defined. It can either raise this new exception directly, in which case all further event listeners are bypassed and the exception will be raised, after appropriate cleanup as taken place:: @event.listens_for(Engine, "handle_error") def handle_exception(context): if isinstance(context.original_exception, psycopg2.OperationalError) and \ "failed" in str(context.original_exception): raise MySpecialException("failed operation") .. warning:: Because the :meth:`_events.DialectEvents.handle_error` event specifically provides for exceptions to be re-thrown as the ultimate exception raised by the failed statement, **stack traces will be misleading** if the user-defined event handler itself fails and throws an unexpected exception; the stack trace may not illustrate the actual code line that failed! It is advised to code carefully here and use logging and/or inline debugging if unexpected exceptions are occurring. Alternatively, a "chained" style of event handling can be used, by configuring the handler with the ``retval=True`` modifier and returning the new exception instance from the function. In this case, event handling will continue onto the next handler. The "chained" exception is available using :attr:`.ExceptionContext.chained_exception`:: @event.listens_for(Engine, "handle_error", retval=True) def handle_exception(context): if context.chained_exception is not None and \ "special" in context.chained_exception.message: return MySpecialException("failed", cause=context.chained_exception) Handlers that return ``None`` may be used within the chain; when a handler returns ``None``, the previous exception instance, if any, is maintained as the current exception that is passed onto the next handler. When a custom exception is raised or returned, SQLAlchemy raises this new exception as-is, it is not wrapped by any SQLAlchemy object. If the exception is not a subclass of :class:`sqlalchemy.exc.StatementError`, certain features may not be available; currently this includes the ORM's feature of adding a detail hint about "autoflush" to exceptions raised within the autoflush process. :param context: an :class:`.ExceptionContext` object. See this class for details on all available members. .. seealso:: :ref:`pool_new_disconnect_codes` """ def do_connect( self, dialect: Dialect, conn_rec: ConnectionPoolEntry, cargs: Tuple[Any, ...], cparams: Dict[str, Any], ) -> Optional[DBAPIConnection]: """Receive connection arguments before a connection is made. This event is useful in that it allows the handler to manipulate the cargs and/or cparams collections that control how the DBAPI ``connect()`` function will be called. ``cargs`` will always be a Python list that can be mutated in-place, and ``cparams`` a Python dictionary that may also be mutated:: e = create_engine("postgresql+psycopg2://user@host/dbname") @event.listens_for(e, 'do_connect') def receive_do_connect(dialect, conn_rec, cargs, cparams): cparams["password"] = "some_password" The event hook may also be used to override the call to ``connect()`` entirely, by returning a non-``None`` DBAPI connection object:: e = create_engine("postgresql+psycopg2://user@host/dbname") @event.listens_for(e, 'do_connect') def receive_do_connect(dialect, conn_rec, cargs, cparams): return psycopg2.connect(*cargs, **cparams) .. seealso:: :ref:`custom_dbapi_args` """ def do_executemany( self, cursor: DBAPICursor, statement: str, parameters: _DBAPIMultiExecuteParams, context: ExecutionContext, ) -> Optional[Literal[True]]: """Receive a cursor to have executemany() called. Return the value True to halt further events from invoking, and to indicate that the cursor execution has already taken place within the event handler. """ def do_execute_no_params( self, cursor: DBAPICursor, statement: str, context: ExecutionContext ) -> Optional[Literal[True]]: """Receive a cursor to have execute() with no parameters called. Return the value True to halt further events from invoking, and to indicate that the cursor execution has already taken place within the event handler. """ def do_execute( self, cursor: DBAPICursor, statement: str, parameters: _DBAPISingleExecuteParams, context: ExecutionContext, ) -> Optional[Literal[True]]: """Receive a cursor to have execute() called. Return the value True to halt further events from invoking, and to indicate that the cursor execution has already taken place within the event handler. """ def do_setinputsizes( self, inputsizes: Dict[BindParameter[Any], Any], cursor: DBAPICursor, statement: str, parameters: _DBAPIAnyExecuteParams, context: ExecutionContext, ) -> None: """Receive the setinputsizes dictionary for possible modification. This event is emitted in the case where the dialect makes use of the DBAPI ``cursor.setinputsizes()`` method which passes information about parameter binding for a particular statement. The given ``inputsizes`` dictionary will contain :class:`.BindParameter` objects as keys, linked to DBAPI-specific type objects as values; for parameters that are not bound, they are added to the dictionary with ``None`` as the value, which means the parameter will not be included in the ultimate setinputsizes call. The event may be used to inspect and/or log the datatypes that are being bound, as well as to modify the dictionary in place. Parameters can be added, modified, or removed from this dictionary. Callers will typically want to inspect the :attr:`.BindParameter.type` attribute of the given bind objects in order to make decisions about the DBAPI object. After the event, the ``inputsizes`` dictionary is converted into an appropriate datastructure to be passed to ``cursor.setinputsizes``; either a list for a positional bound parameter execution style, or a dictionary of string parameter keys to DBAPI type objects for a named bound parameter execution style. The setinputsizes hook overall is only used for dialects which include the flag ``use_setinputsizes=True``. Dialects which use this include cx_Oracle, pg8000, asyncpg, and pyodbc dialects. .. note:: For use with pyodbc, the ``use_setinputsizes`` flag must be passed to the dialect, e.g.:: create_engine("mssql+pyodbc://...", use_setinputsizes=True) .. seealso:: :ref:`mssql_pyodbc_setinputsizes` .. versionadded:: 1.2.9 .. seealso:: :ref:`cx_oracle_setinputsizes` """ pass