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: /proc/self/root/opt/hc_python/lib64/python3.8/site-packages/sqlalchemy/engine/ Upload File: files >> //proc/self/root/opt/hc_python/lib64/python3.8/site-packages/sqlalchemy/engine/base.py # engine/base.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 """Defines :class:`_engine.Connection` and :class:`_engine.Engine`. """ from __future__ import annotations import contextlib import sys import typing from typing import Any from typing import Callable from typing import cast from typing import Iterable from typing import Iterator from typing import List from typing import Mapping from typing import NoReturn from typing import Optional from typing import overload from typing import Tuple from typing import Type from typing import TypeVar from typing import Union from .interfaces import BindTyping from .interfaces import ConnectionEventsTarget from .interfaces import DBAPICursor from .interfaces import ExceptionContext from .interfaces import ExecuteStyle from .interfaces import ExecutionContext from .interfaces import IsolationLevel from .util import _distill_params_20 from .util import _distill_raw_params from .util import TransactionalContext from .. import exc from .. import inspection from .. import log from .. import util from ..sql import compiler from ..sql import util as sql_util if typing.TYPE_CHECKING: from . import CursorResult from . import ScalarResult from .interfaces import _AnyExecuteParams from .interfaces import _AnyMultiExecuteParams from .interfaces import _CoreAnyExecuteParams from .interfaces import _CoreMultiExecuteParams from .interfaces import _CoreSingleExecuteParams from .interfaces import _DBAPIAnyExecuteParams from .interfaces import _DBAPISingleExecuteParams from .interfaces import _ExecuteOptions from .interfaces import CompiledCacheType from .interfaces import CoreExecuteOptionsParameter from .interfaces import Dialect from .interfaces import SchemaTranslateMapType from .reflection import Inspector # noqa from .url import URL from ..event import dispatcher from ..log import _EchoFlagType from ..pool import _ConnectionFairy from ..pool import Pool from ..pool import PoolProxiedConnection from ..sql import Executable from ..sql._typing import _InfoType from ..sql.compiler import Compiled from ..sql.ddl import ExecutableDDLElement from ..sql.ddl import SchemaDropper from ..sql.ddl import SchemaGenerator from ..sql.functions import FunctionElement from ..sql.schema import DefaultGenerator from ..sql.schema import HasSchemaAttr from ..sql.schema import SchemaItem from ..sql.selectable import TypedReturnsRows _T = TypeVar("_T", bound=Any) _EMPTY_EXECUTION_OPTS: _ExecuteOptions = util.EMPTY_DICT NO_OPTIONS: Mapping[str, Any] = util.EMPTY_DICT class Connection(ConnectionEventsTarget, inspection.Inspectable["Inspector"]): """Provides high-level functionality for a wrapped DB-API connection. The :class:`_engine.Connection` object is procured by calling the :meth:`_engine.Engine.connect` method of the :class:`_engine.Engine` object, and provides services for execution of SQL statements as well as transaction control. The Connection object is **not** thread-safe. While a Connection can be shared among threads using properly synchronized access, it is still possible that the underlying DBAPI connection may not support shared access between threads. Check the DBAPI documentation for details. The Connection object represents a single DBAPI connection checked out from the connection pool. In this state, the connection pool has no affect upon the connection, including its expiration or timeout state. For the connection pool to properly manage connections, connections should be returned to the connection pool (i.e. ``connection.close()``) whenever the connection is not in use. .. index:: single: thread safety; Connection """ dialect: Dialect dispatch: dispatcher[ConnectionEventsTarget] _sqla_logger_namespace = "sqlalchemy.engine.Connection" # used by sqlalchemy.engine.util.TransactionalContext _trans_context_manager: Optional[TransactionalContext] = None # legacy as of 2.0, should be eventually deprecated and # removed. was used in the "pre_ping" recipe that's been in the docs # a long time should_close_with_result = False _dbapi_connection: Optional[PoolProxiedConnection] _execution_options: _ExecuteOptions _transaction: Optional[RootTransaction] _nested_transaction: Optional[NestedTransaction] def __init__( self, engine: Engine, connection: Optional[PoolProxiedConnection] = None, _has_events: Optional[bool] = None, _allow_revalidate: bool = True, _allow_autobegin: bool = True, ): """Construct a new Connection.""" self.engine = engine self.dialect = dialect = engine.dialect if connection is None: try: self._dbapi_connection = engine.raw_connection() except dialect.loaded_dbapi.Error as err: Connection._handle_dbapi_exception_noconnection( err, dialect, engine ) raise else: self._dbapi_connection = connection self._transaction = self._nested_transaction = None self.__savepoint_seq = 0 self.__in_begin = False self.__can_reconnect = _allow_revalidate self._allow_autobegin = _allow_autobegin self._echo = self.engine._should_log_info() if _has_events is None: # if _has_events is sent explicitly as False, # then don't join the dispatch of the engine; we don't # want to handle any of the engine's events in that case. self.dispatch = self.dispatch._join(engine.dispatch) self._has_events = _has_events or ( _has_events is None and engine._has_events ) self._execution_options = engine._execution_options if self._has_events or self.engine._has_events: self.dispatch.engine_connect(self) # this can be assigned differently via # characteristics.LoggingTokenCharacteristic _message_formatter: Any = None def _log_info(self, message: str, *arg: Any, **kw: Any) -> None: fmt = self._message_formatter if fmt: message = fmt(message) if log.STACKLEVEL: kw["stacklevel"] = 1 + log.STACKLEVEL_OFFSET self.engine.logger.info(message, *arg, **kw) def _log_debug(self, message: str, *arg: Any, **kw: Any) -> None: fmt = self._message_formatter if fmt: message = fmt(message) if log.STACKLEVEL: kw["stacklevel"] = 1 + log.STACKLEVEL_OFFSET self.engine.logger.debug(message, *arg, **kw) @property def _schema_translate_map(self) -> Optional[SchemaTranslateMapType]: schema_translate_map: Optional[SchemaTranslateMapType] = ( self._execution_options.get("schema_translate_map", None) ) return schema_translate_map def schema_for_object(self, obj: HasSchemaAttr) -> Optional[str]: """Return the schema name for the given schema item taking into account current schema translate map. """ name = obj.schema schema_translate_map: Optional[SchemaTranslateMapType] = ( self._execution_options.get("schema_translate_map", None) ) if ( schema_translate_map and name in schema_translate_map and obj._use_schema_map ): return schema_translate_map[name] else: return name def __enter__(self) -> Connection: return self def __exit__(self, type_: Any, value: Any, traceback: Any) -> None: self.close() @overload def execution_options( self, *, compiled_cache: Optional[CompiledCacheType] = ..., logging_token: str = ..., isolation_level: IsolationLevel = ..., no_parameters: bool = False, stream_results: bool = False, max_row_buffer: int = ..., yield_per: int = ..., insertmanyvalues_page_size: int = ..., schema_translate_map: Optional[SchemaTranslateMapType] = ..., preserve_rowcount: bool = False, **opt: Any, ) -> Connection: ... @overload def execution_options(self, **opt: Any) -> Connection: ... def execution_options(self, **opt: Any) -> Connection: r"""Set non-SQL options for the connection which take effect during execution. This method modifies this :class:`_engine.Connection` **in-place**; the return value is the same :class:`_engine.Connection` object upon which the method is called. Note that this is in contrast to the behavior of the ``execution_options`` methods on other objects such as :meth:`_engine.Engine.execution_options` and :meth:`_sql.Executable.execution_options`. The rationale is that many such execution options necessarily modify the state of the base DBAPI connection in any case so there is no feasible means of keeping the effect of such an option localized to a "sub" connection. .. versionchanged:: 2.0 The :meth:`_engine.Connection.execution_options` method, in contrast to other objects with this method, modifies the connection in-place without creating copy of it. As discussed elsewhere, the :meth:`_engine.Connection.execution_options` method accepts any arbitrary parameters including user defined names. All parameters given are consumable in a number of ways including by using the :meth:`_engine.Connection.get_execution_options` method. See the examples at :meth:`_sql.Executable.execution_options` and :meth:`_engine.Engine.execution_options`. The keywords that are currently recognized by SQLAlchemy itself include all those listed under :meth:`.Executable.execution_options`, as well as others that are specific to :class:`_engine.Connection`. :param compiled_cache: Available on: :class:`_engine.Connection`, :class:`_engine.Engine`. A dictionary where :class:`.Compiled` objects will be cached when the :class:`_engine.Connection` compiles a clause expression into a :class:`.Compiled` object. This dictionary will supersede the statement cache that may be configured on the :class:`_engine.Engine` itself. If set to None, caching is disabled, even if the engine has a configured cache size. Note that the ORM makes use of its own "compiled" caches for some operations, including flush operations. The caching used by the ORM internally supersedes a cache dictionary specified here. :param logging_token: Available on: :class:`_engine.Connection`, :class:`_engine.Engine`, :class:`_sql.Executable`. Adds the specified string token surrounded by brackets in log messages logged by the connection, i.e. the logging that's enabled either via the :paramref:`_sa.create_engine.echo` flag or via the ``logging.getLogger("sqlalchemy.engine")`` logger. This allows a per-connection or per-sub-engine token to be available which is useful for debugging concurrent connection scenarios. .. versionadded:: 1.4.0b2 .. seealso:: :ref:`dbengine_logging_tokens` - usage example :paramref:`_sa.create_engine.logging_name` - adds a name to the name used by the Python logger object itself. :param isolation_level: Available on: :class:`_engine.Connection`, :class:`_engine.Engine`. Set the transaction isolation level for the lifespan of this :class:`_engine.Connection` object. Valid values include those string values accepted by the :paramref:`_sa.create_engine.isolation_level` parameter passed to :func:`_sa.create_engine`. These levels are semi-database specific; see individual dialect documentation for valid levels. The isolation level option applies the isolation level by emitting statements on the DBAPI connection, and **necessarily affects the original Connection object overall**. The isolation level will remain at the given setting until explicitly changed, or when the DBAPI connection itself is :term:`released` to the connection pool, i.e. the :meth:`_engine.Connection.close` method is called, at which time an event handler will emit additional statements on the DBAPI connection in order to revert the isolation level change. .. note:: The ``isolation_level`` execution option may only be established before the :meth:`_engine.Connection.begin` method is called, as well as before any SQL statements are emitted which would otherwise trigger "autobegin", or directly after a call to :meth:`_engine.Connection.commit` or :meth:`_engine.Connection.rollback`. A database cannot change the isolation level on a transaction in progress. .. note:: The ``isolation_level`` execution option is implicitly reset if the :class:`_engine.Connection` is invalidated, e.g. via the :meth:`_engine.Connection.invalidate` method, or if a disconnection error occurs. The new connection produced after the invalidation will **not** have the selected isolation level re-applied to it automatically. .. seealso:: :ref:`dbapi_autocommit` :meth:`_engine.Connection.get_isolation_level` - view current actual level :param no_parameters: Available on: :class:`_engine.Connection`, :class:`_sql.Executable`. When ``True``, if the final parameter list or dictionary is totally empty, will invoke the statement on the cursor as ``cursor.execute(statement)``, not passing the parameter collection at all. Some DBAPIs such as psycopg2 and mysql-python consider percent signs as significant only when parameters are present; this option allows code to generate SQL containing percent signs (and possibly other characters) that is neutral regarding whether it's executed by the DBAPI or piped into a script that's later invoked by command line tools. :param stream_results: Available on: :class:`_engine.Connection`, :class:`_sql.Executable`. Indicate to the dialect that results should be "streamed" and not pre-buffered, if possible. For backends such as PostgreSQL, MySQL and MariaDB, this indicates the use of a "server side cursor" as opposed to a client side cursor. Other backends such as that of Oracle may already use server side cursors by default. The usage of :paramref:`_engine.Connection.execution_options.stream_results` is usually combined with setting a fixed number of rows to to be fetched in batches, to allow for efficient iteration of database rows while at the same time not loading all result rows into memory at once; this can be configured on a :class:`_engine.Result` object using the :meth:`_engine.Result.yield_per` method, after execution has returned a new :class:`_engine.Result`. If :meth:`_engine.Result.yield_per` is not used, the :paramref:`_engine.Connection.execution_options.stream_results` mode of operation will instead use a dynamically sized buffer which buffers sets of rows at a time, growing on each batch based on a fixed growth size up until a limit which may be configured using the :paramref:`_engine.Connection.execution_options.max_row_buffer` parameter. When using the ORM to fetch ORM mapped objects from a result, :meth:`_engine.Result.yield_per` should always be used with :paramref:`_engine.Connection.execution_options.stream_results`, so that the ORM does not fetch all rows into new ORM objects at once. For typical use, the :paramref:`_engine.Connection.execution_options.yield_per` execution option should be preferred, which sets up both :paramref:`_engine.Connection.execution_options.stream_results` and :meth:`_engine.Result.yield_per` at once. This option is supported both at a core level by :class:`_engine.Connection` as well as by the ORM :class:`_engine.Session`; the latter is described at :ref:`orm_queryguide_yield_per`. .. seealso:: :ref:`engine_stream_results` - background on :paramref:`_engine.Connection.execution_options.stream_results` :paramref:`_engine.Connection.execution_options.max_row_buffer` :paramref:`_engine.Connection.execution_options.yield_per` :ref:`orm_queryguide_yield_per` - in the :ref:`queryguide_toplevel` describing the ORM version of ``yield_per`` :param max_row_buffer: Available on: :class:`_engine.Connection`, :class:`_sql.Executable`. Sets a maximum buffer size to use when the :paramref:`_engine.Connection.execution_options.stream_results` execution option is used on a backend that supports server side cursors. The default value if not specified is 1000. .. seealso:: :paramref:`_engine.Connection.execution_options.stream_results` :ref:`engine_stream_results` :param yield_per: Available on: :class:`_engine.Connection`, :class:`_sql.Executable`. Integer value applied which will set the :paramref:`_engine.Connection.execution_options.stream_results` execution option and invoke :meth:`_engine.Result.yield_per` automatically at once. Allows equivalent functionality as is present when using this parameter with the ORM. .. versionadded:: 1.4.40 .. seealso:: :ref:`engine_stream_results` - background and examples on using server side cursors with Core. :ref:`orm_queryguide_yield_per` - in the :ref:`queryguide_toplevel` describing the ORM version of ``yield_per`` :param insertmanyvalues_page_size: Available on: :class:`_engine.Connection`, :class:`_engine.Engine`. Number of rows to format into an INSERT statement when the statement uses "insertmanyvalues" mode, which is a paged form of bulk insert that is used for many backends when using :term:`executemany` execution typically in conjunction with RETURNING. Defaults to 1000. May also be modified on a per-engine basis using the :paramref:`_sa.create_engine.insertmanyvalues_page_size` parameter. .. versionadded:: 2.0 .. seealso:: :ref:`engine_insertmanyvalues` :param schema_translate_map: Available on: :class:`_engine.Connection`, :class:`_engine.Engine`, :class:`_sql.Executable`. A dictionary mapping schema names to schema names, that will be applied to the :paramref:`_schema.Table.schema` element of each :class:`_schema.Table` encountered when SQL or DDL expression elements are compiled into strings; the resulting schema name will be converted based on presence in the map of the original name. .. seealso:: :ref:`schema_translating` :param preserve_rowcount: Boolean; when True, the ``cursor.rowcount`` attribute will be unconditionally memoized within the result and made available via the :attr:`.CursorResult.rowcount` attribute. Normally, this attribute is only preserved for UPDATE and DELETE statements. Using this option, the DBAPIs rowcount value can be accessed for other kinds of statements such as INSERT and SELECT, to the degree that the DBAPI supports these statements. See :attr:`.CursorResult.rowcount` for notes regarding the behavior of this attribute. .. versionadded:: 2.0.28 .. seealso:: :meth:`_engine.Engine.execution_options` :meth:`.Executable.execution_options` :meth:`_engine.Connection.get_execution_options` :ref:`orm_queryguide_execution_options` - documentation on all ORM-specific execution options """ # noqa if self._has_events or self.engine._has_events: self.dispatch.set_connection_execution_options(self, opt) self._execution_options = self._execution_options.union(opt) self.dialect.set_connection_execution_options(self, opt) return self def get_execution_options(self) -> _ExecuteOptions: """Get the non-SQL options which will take effect during execution. .. versionadded:: 1.3 .. seealso:: :meth:`_engine.Connection.execution_options` """ return self._execution_options @property def _still_open_and_dbapi_connection_is_valid(self) -> bool: pool_proxied_connection = self._dbapi_connection return ( pool_proxied_connection is not None and pool_proxied_connection.is_valid ) @property def closed(self) -> bool: """Return True if this connection is closed.""" return self._dbapi_connection is None and not self.__can_reconnect @property def invalidated(self) -> bool: """Return True if this connection was invalidated. This does not indicate whether or not the connection was invalidated at the pool level, however """ # prior to 1.4, "invalid" was stored as a state independent of # "closed", meaning an invalidated connection could be "closed", # the _dbapi_connection would be None and closed=True, yet the # "invalid" flag would stay True. This meant that there were # three separate states (open/valid, closed/valid, closed/invalid) # when there is really no reason for that; a connection that's # "closed" does not need to be "invalid". So the state is now # represented by the two facts alone. pool_proxied_connection = self._dbapi_connection return pool_proxied_connection is None and self.__can_reconnect @property def connection(self) -> PoolProxiedConnection: """The underlying DB-API connection managed by this Connection. This is a SQLAlchemy connection-pool proxied connection which then has the attribute :attr:`_pool._ConnectionFairy.dbapi_connection` that refers to the actual driver connection. .. seealso:: :ref:`dbapi_connections` """ if self._dbapi_connection is None: try: return self._revalidate_connection() except (exc.PendingRollbackError, exc.ResourceClosedError): raise except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) else: return self._dbapi_connection def get_isolation_level(self) -> IsolationLevel: """Return the current **actual** isolation level that's present on the database within the scope of this connection. This attribute will perform a live SQL operation against the database in order to procure the current isolation level, so the value returned is the actual level on the underlying DBAPI connection regardless of how this state was set. This will be one of the four actual isolation modes ``READ UNCOMMITTED``, ``READ COMMITTED``, ``REPEATABLE READ``, ``SERIALIZABLE``. It will **not** include the ``AUTOCOMMIT`` isolation level setting. Third party dialects may also feature additional isolation level settings. .. note:: This method **will not report** on the ``AUTOCOMMIT`` isolation level, which is a separate :term:`dbapi` setting that's independent of **actual** isolation level. When ``AUTOCOMMIT`` is in use, the database connection still has a "traditional" isolation mode in effect, that is typically one of the four values ``READ UNCOMMITTED``, ``READ COMMITTED``, ``REPEATABLE READ``, ``SERIALIZABLE``. Compare to the :attr:`_engine.Connection.default_isolation_level` accessor which returns the isolation level that is present on the database at initial connection time. .. seealso:: :attr:`_engine.Connection.default_isolation_level` - view default level :paramref:`_sa.create_engine.isolation_level` - set per :class:`_engine.Engine` isolation level :paramref:`.Connection.execution_options.isolation_level` - set per :class:`_engine.Connection` isolation level """ dbapi_connection = self.connection.dbapi_connection assert dbapi_connection is not None try: return self.dialect.get_isolation_level(dbapi_connection) except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) @property def default_isolation_level(self) -> Optional[IsolationLevel]: """The initial-connection time isolation level associated with the :class:`_engine.Dialect` in use. This value is independent of the :paramref:`.Connection.execution_options.isolation_level` and :paramref:`.Engine.execution_options.isolation_level` execution options, and is determined by the :class:`_engine.Dialect` when the first connection is created, by performing a SQL query against the database for the current isolation level before any additional commands have been emitted. Calling this accessor does not invoke any new SQL queries. .. seealso:: :meth:`_engine.Connection.get_isolation_level` - view current actual isolation level :paramref:`_sa.create_engine.isolation_level` - set per :class:`_engine.Engine` isolation level :paramref:`.Connection.execution_options.isolation_level` - set per :class:`_engine.Connection` isolation level """ return self.dialect.default_isolation_level def _invalid_transaction(self) -> NoReturn: raise exc.PendingRollbackError( "Can't reconnect until invalid %stransaction is rolled " "back. Please rollback() fully before proceeding" % ("savepoint " if self._nested_transaction is not None else ""), code="8s2b", ) def _revalidate_connection(self) -> PoolProxiedConnection: if self.__can_reconnect and self.invalidated: if self._transaction is not None: self._invalid_transaction() self._dbapi_connection = self.engine.raw_connection() return self._dbapi_connection raise exc.ResourceClosedError("This Connection is closed") @property def info(self) -> _InfoType: """Info dictionary associated with the underlying DBAPI connection referred to by this :class:`_engine.Connection`, allowing user-defined data to be associated with the connection. The data here will follow along with the DBAPI connection including after it is returned to the connection pool and used again in subsequent instances of :class:`_engine.Connection`. """ return self.connection.info def invalidate(self, exception: Optional[BaseException] = None) -> None: """Invalidate the underlying DBAPI connection associated with this :class:`_engine.Connection`. An attempt will be made to close the underlying DBAPI connection immediately; however if this operation fails, the error is logged but not raised. The connection is then discarded whether or not close() succeeded. Upon the next use (where "use" typically means using the :meth:`_engine.Connection.execute` method or similar), this :class:`_engine.Connection` will attempt to procure a new DBAPI connection using the services of the :class:`_pool.Pool` as a source of connectivity (e.g. a "reconnection"). If a transaction was in progress (e.g. the :meth:`_engine.Connection.begin` method has been called) when :meth:`_engine.Connection.invalidate` method is called, at the DBAPI level all state associated with this transaction is lost, as the DBAPI connection is closed. The :class:`_engine.Connection` will not allow a reconnection to proceed until the :class:`.Transaction` object is ended, by calling the :meth:`.Transaction.rollback` method; until that point, any attempt at continuing to use the :class:`_engine.Connection` will raise an :class:`~sqlalchemy.exc.InvalidRequestError`. This is to prevent applications from accidentally continuing an ongoing transactional operations despite the fact that the transaction has been lost due to an invalidation. The :meth:`_engine.Connection.invalidate` method, just like auto-invalidation, will at the connection pool level invoke the :meth:`_events.PoolEvents.invalidate` event. :param exception: an optional ``Exception`` instance that's the reason for the invalidation. is passed along to event handlers and logging functions. .. seealso:: :ref:`pool_connection_invalidation` """ if self.invalidated: return if self.closed: raise exc.ResourceClosedError("This Connection is closed") if self._still_open_and_dbapi_connection_is_valid: pool_proxied_connection = self._dbapi_connection assert pool_proxied_connection is not None pool_proxied_connection.invalidate(exception) self._dbapi_connection = None def detach(self) -> None: """Detach the underlying DB-API connection from its connection pool. E.g.:: with engine.connect() as conn: conn.detach() conn.execute(text("SET search_path TO schema1, schema2")) # work with connection # connection is fully closed (since we used "with:", can # also call .close()) This :class:`_engine.Connection` instance will remain usable. When closed (or exited from a context manager context as above), the DB-API connection will be literally closed and not returned to its originating pool. This method can be used to insulate the rest of an application from a modified state on a connection (such as a transaction isolation level or similar). """ if self.closed: raise exc.ResourceClosedError("This Connection is closed") pool_proxied_connection = self._dbapi_connection if pool_proxied_connection is None: raise exc.InvalidRequestError( "Can't detach an invalidated Connection" ) pool_proxied_connection.detach() def _autobegin(self) -> None: if self._allow_autobegin and not self.__in_begin: self.begin() def begin(self) -> RootTransaction: """Begin a transaction prior to autobegin occurring. E.g.:: with engine.connect() as conn: with conn.begin() as trans: conn.execute(table.insert(), {"username": "sandy"}) The returned object is an instance of :class:`_engine.RootTransaction`. This object represents the "scope" of the transaction, which completes when either the :meth:`_engine.Transaction.rollback` or :meth:`_engine.Transaction.commit` method is called; the object also works as a context manager as illustrated above. The :meth:`_engine.Connection.begin` method begins a transaction that normally will be begun in any case when the connection is first used to execute a statement. The reason this method might be used would be to invoke the :meth:`_events.ConnectionEvents.begin` event at a specific time, or to organize code within the scope of a connection checkout in terms of context managed blocks, such as:: with engine.connect() as conn: with conn.begin(): conn.execute(...) conn.execute(...) with conn.begin(): conn.execute(...) conn.execute(...) The above code is not fundamentally any different in its behavior than the following code which does not use :meth:`_engine.Connection.begin`; the below style is known as "commit as you go" style:: with engine.connect() as conn: conn.execute(...) conn.execute(...) conn.commit() conn.execute(...) conn.execute(...) conn.commit() From a database point of view, the :meth:`_engine.Connection.begin` method does not emit any SQL or change the state of the underlying DBAPI connection in any way; the Python DBAPI does not have any concept of explicit transaction begin. .. seealso:: :ref:`tutorial_working_with_transactions` - in the :ref:`unified_tutorial` :meth:`_engine.Connection.begin_nested` - use a SAVEPOINT :meth:`_engine.Connection.begin_twophase` - use a two phase /XID transaction :meth:`_engine.Engine.begin` - context manager available from :class:`_engine.Engine` """ if self._transaction is None: self._transaction = RootTransaction(self) return self._transaction else: raise exc.InvalidRequestError( "This connection has already initialized a SQLAlchemy " "Transaction() object via begin() or autobegin; can't " "call begin() here unless rollback() or commit() " "is called first." ) def begin_nested(self) -> NestedTransaction: """Begin a nested transaction (i.e. SAVEPOINT) and return a transaction handle that controls the scope of the SAVEPOINT. E.g.:: with engine.begin() as connection: with connection.begin_nested(): connection.execute(table.insert(), {"username": "sandy"}) The returned object is an instance of :class:`_engine.NestedTransaction`, which includes transactional methods :meth:`_engine.NestedTransaction.commit` and :meth:`_engine.NestedTransaction.rollback`; for a nested transaction, these methods correspond to the operations "RELEASE SAVEPOINT <name>" and "ROLLBACK TO SAVEPOINT <name>". The name of the savepoint is local to the :class:`_engine.NestedTransaction` object and is generated automatically. Like any other :class:`_engine.Transaction`, the :class:`_engine.NestedTransaction` may be used as a context manager as illustrated above which will "release" or "rollback" corresponding to if the operation within the block were successful or raised an exception. Nested transactions require SAVEPOINT support in the underlying database, else the behavior is undefined. SAVEPOINT is commonly used to run operations within a transaction that may fail, while continuing the outer transaction. E.g.:: from sqlalchemy import exc with engine.begin() as connection: trans = connection.begin_nested() try: connection.execute(table.insert(), {"username": "sandy"}) trans.commit() except exc.IntegrityError: # catch for duplicate username trans.rollback() # rollback to savepoint # outer transaction continues connection.execute( ... ) If :meth:`_engine.Connection.begin_nested` is called without first calling :meth:`_engine.Connection.begin` or :meth:`_engine.Engine.begin`, the :class:`_engine.Connection` object will "autobegin" the outer transaction first. This outer transaction may be committed using "commit-as-you-go" style, e.g.:: with engine.connect() as connection: # begin() wasn't called with connection.begin_nested(): will auto-"begin()" first connection.execute( ... ) # savepoint is released connection.execute( ... ) # explicitly commit outer transaction connection.commit() # can continue working with connection here .. versionchanged:: 2.0 :meth:`_engine.Connection.begin_nested` will now participate in the connection "autobegin" behavior that is new as of 2.0 / "future" style connections in 1.4. .. seealso:: :meth:`_engine.Connection.begin` :ref:`session_begin_nested` - ORM support for SAVEPOINT """ if self._transaction is None: self._autobegin() return NestedTransaction(self) def begin_twophase(self, xid: Optional[Any] = None) -> TwoPhaseTransaction: """Begin a two-phase or XA transaction and return a transaction handle. The returned object is an instance of :class:`.TwoPhaseTransaction`, which in addition to the methods provided by :class:`.Transaction`, also provides a :meth:`~.TwoPhaseTransaction.prepare` method. :param xid: the two phase transaction id. If not supplied, a random id will be generated. .. seealso:: :meth:`_engine.Connection.begin` :meth:`_engine.Connection.begin_twophase` """ if self._transaction is not None: raise exc.InvalidRequestError( "Cannot start a two phase transaction when a transaction " "is already in progress." ) if xid is None: xid = self.engine.dialect.create_xid() return TwoPhaseTransaction(self, xid) def commit(self) -> None: """Commit the transaction that is currently in progress. This method commits the current transaction if one has been started. If no transaction was started, the method has no effect, assuming the connection is in a non-invalidated state. A transaction is begun on a :class:`_engine.Connection` automatically whenever a statement is first executed, or when the :meth:`_engine.Connection.begin` method is called. .. note:: The :meth:`_engine.Connection.commit` method only acts upon the primary database transaction that is linked to the :class:`_engine.Connection` object. It does not operate upon a SAVEPOINT that would have been invoked from the :meth:`_engine.Connection.begin_nested` method; for control of a SAVEPOINT, call :meth:`_engine.NestedTransaction.commit` on the :class:`_engine.NestedTransaction` that is returned by the :meth:`_engine.Connection.begin_nested` method itself. """ if self._transaction: self._transaction.commit() def rollback(self) -> None: """Roll back the transaction that is currently in progress. This method rolls back the current transaction if one has been started. If no transaction was started, the method has no effect. If a transaction was started and the connection is in an invalidated state, the transaction is cleared using this method. A transaction is begun on a :class:`_engine.Connection` automatically whenever a statement is first executed, or when the :meth:`_engine.Connection.begin` method is called. .. note:: The :meth:`_engine.Connection.rollback` method only acts upon the primary database transaction that is linked to the :class:`_engine.Connection` object. It does not operate upon a SAVEPOINT that would have been invoked from the :meth:`_engine.Connection.begin_nested` method; for control of a SAVEPOINT, call :meth:`_engine.NestedTransaction.rollback` on the :class:`_engine.NestedTransaction` that is returned by the :meth:`_engine.Connection.begin_nested` method itself. """ if self._transaction: self._transaction.rollback() def recover_twophase(self) -> List[Any]: return self.engine.dialect.do_recover_twophase(self) def rollback_prepared(self, xid: Any, recover: bool = False) -> None: self.engine.dialect.do_rollback_twophase(self, xid, recover=recover) def commit_prepared(self, xid: Any, recover: bool = False) -> None: self.engine.dialect.do_commit_twophase(self, xid, recover=recover) def in_transaction(self) -> bool: """Return True if a transaction is in progress.""" return self._transaction is not None and self._transaction.is_active def in_nested_transaction(self) -> bool: """Return True if a transaction is in progress.""" return ( self._nested_transaction is not None and self._nested_transaction.is_active ) def _is_autocommit_isolation(self) -> bool: opt_iso = self._execution_options.get("isolation_level", None) return bool( opt_iso == "AUTOCOMMIT" or ( opt_iso is None and self.engine.dialect._on_connect_isolation_level == "AUTOCOMMIT" ) ) def _get_required_transaction(self) -> RootTransaction: trans = self._transaction if trans is None: raise exc.InvalidRequestError("connection is not in a transaction") return trans def _get_required_nested_transaction(self) -> NestedTransaction: trans = self._nested_transaction if trans is None: raise exc.InvalidRequestError( "connection is not in a nested transaction" ) return trans def get_transaction(self) -> Optional[RootTransaction]: """Return the current root transaction in progress, if any. .. versionadded:: 1.4 """ return self._transaction def get_nested_transaction(self) -> Optional[NestedTransaction]: """Return the current nested transaction in progress, if any. .. versionadded:: 1.4 """ return self._nested_transaction def _begin_impl(self, transaction: RootTransaction) -> None: if self._echo: if self._is_autocommit_isolation(): self._log_info( "BEGIN (implicit; DBAPI should not BEGIN due to " "autocommit mode)" ) else: self._log_info("BEGIN (implicit)") self.__in_begin = True if self._has_events or self.engine._has_events: self.dispatch.begin(self) try: self.engine.dialect.do_begin(self.connection) except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) finally: self.__in_begin = False def _rollback_impl(self) -> None: if self._has_events or self.engine._has_events: self.dispatch.rollback(self) if self._still_open_and_dbapi_connection_is_valid: if self._echo: if self._is_autocommit_isolation(): self._log_info( "ROLLBACK using DBAPI connection.rollback(), " "DBAPI should ignore due to autocommit mode" ) else: self._log_info("ROLLBACK") try: self.engine.dialect.do_rollback(self.connection) except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) def _commit_impl(self) -> None: if self._has_events or self.engine._has_events: self.dispatch.commit(self) if self._echo: if self._is_autocommit_isolation(): self._log_info( "COMMIT using DBAPI connection.commit(), " "DBAPI should ignore due to autocommit mode" ) else: self._log_info("COMMIT") try: self.engine.dialect.do_commit(self.connection) except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) def _savepoint_impl(self, name: Optional[str] = None) -> str: if self._has_events or self.engine._has_events: self.dispatch.savepoint(self, name) if name is None: self.__savepoint_seq += 1 name = "sa_savepoint_%s" % self.__savepoint_seq self.engine.dialect.do_savepoint(self, name) return name def _rollback_to_savepoint_impl(self, name: str) -> None: if self._has_events or self.engine._has_events: self.dispatch.rollback_savepoint(self, name, None) if self._still_open_and_dbapi_connection_is_valid: self.engine.dialect.do_rollback_to_savepoint(self, name) def _release_savepoint_impl(self, name: str) -> None: if self._has_events or self.engine._has_events: self.dispatch.release_savepoint(self, name, None) self.engine.dialect.do_release_savepoint(self, name) def _begin_twophase_impl(self, transaction: TwoPhaseTransaction) -> None: if self._echo: self._log_info("BEGIN TWOPHASE (implicit)") if self._has_events or self.engine._has_events: self.dispatch.begin_twophase(self, transaction.xid) self.__in_begin = True try: self.engine.dialect.do_begin_twophase(self, transaction.xid) except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) finally: self.__in_begin = False def _prepare_twophase_impl(self, xid: Any) -> None: if self._has_events or self.engine._has_events: self.dispatch.prepare_twophase(self, xid) assert isinstance(self._transaction, TwoPhaseTransaction) try: self.engine.dialect.do_prepare_twophase(self, xid) except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) def _rollback_twophase_impl(self, xid: Any, is_prepared: bool) -> None: if self._has_events or self.engine._has_events: self.dispatch.rollback_twophase(self, xid, is_prepared) if self._still_open_and_dbapi_connection_is_valid: assert isinstance(self._transaction, TwoPhaseTransaction) try: self.engine.dialect.do_rollback_twophase( self, xid, is_prepared ) except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) def _commit_twophase_impl(self, xid: Any, is_prepared: bool) -> None: if self._has_events or self.engine._has_events: self.dispatch.commit_twophase(self, xid, is_prepared) assert isinstance(self._transaction, TwoPhaseTransaction) try: self.engine.dialect.do_commit_twophase(self, xid, is_prepared) except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) def close(self) -> None: """Close this :class:`_engine.Connection`. This results in a release of the underlying database resources, that is, the DBAPI connection referenced internally. The DBAPI connection is typically restored back to the connection-holding :class:`_pool.Pool` referenced by the :class:`_engine.Engine` that produced this :class:`_engine.Connection`. Any transactional state present on the DBAPI connection is also unconditionally released via the DBAPI connection's ``rollback()`` method, regardless of any :class:`.Transaction` object that may be outstanding with regards to this :class:`_engine.Connection`. This has the effect of also calling :meth:`_engine.Connection.rollback` if any transaction is in place. After :meth:`_engine.Connection.close` is called, the :class:`_engine.Connection` is permanently in a closed state, and will allow no further operations. """ if self._transaction: self._transaction.close() skip_reset = True else: skip_reset = False if self._dbapi_connection is not None: conn = self._dbapi_connection # as we just closed the transaction, close the connection # pool connection without doing an additional reset if skip_reset: cast("_ConnectionFairy", conn)._close_special( transaction_reset=True ) else: conn.close() # There is a slight chance that conn.close() may have # triggered an invalidation here in which case # _dbapi_connection would already be None, however usually # it will be non-None here and in a "closed" state. self._dbapi_connection = None self.__can_reconnect = False @overload def scalar( self, statement: TypedReturnsRows[Tuple[_T]], parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> Optional[_T]: ... @overload def scalar( self, statement: Executable, parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> Any: ... def scalar( self, statement: Executable, parameters: Optional[_CoreSingleExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> Any: r"""Executes a SQL statement construct and returns a scalar object. This method is shorthand for invoking the :meth:`_engine.Result.scalar` method after invoking the :meth:`_engine.Connection.execute` method. Parameters are equivalent. :return: a scalar Python value representing the first column of the first row returned. """ distilled_parameters = _distill_params_20(parameters) try: meth = statement._execute_on_scalar except AttributeError as err: raise exc.ObjectNotExecutableError(statement) from err else: return meth( self, distilled_parameters, execution_options or NO_OPTIONS, ) @overload def scalars( self, statement: TypedReturnsRows[Tuple[_T]], parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> ScalarResult[_T]: ... @overload def scalars( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> ScalarResult[Any]: ... def scalars( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> ScalarResult[Any]: """Executes and returns a scalar result set, which yields scalar values from the first column of each row. This method is equivalent to calling :meth:`_engine.Connection.execute` to receive a :class:`_result.Result` object, then invoking the :meth:`_result.Result.scalars` method to produce a :class:`_result.ScalarResult` instance. :return: a :class:`_result.ScalarResult` .. versionadded:: 1.4.24 """ return self.execute( statement, parameters, execution_options=execution_options ).scalars() @overload def execute( self, statement: TypedReturnsRows[_T], parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> CursorResult[_T]: ... @overload def execute( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> CursorResult[Any]: ... def execute( self, statement: Executable, parameters: Optional[_CoreAnyExecuteParams] = None, *, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> CursorResult[Any]: r"""Executes a SQL statement construct and returns a :class:`_engine.CursorResult`. :param statement: The statement to be executed. This is always an object that is in both the :class:`_expression.ClauseElement` and :class:`_expression.Executable` hierarchies, including: * :class:`_expression.Select` * :class:`_expression.Insert`, :class:`_expression.Update`, :class:`_expression.Delete` * :class:`_expression.TextClause` and :class:`_expression.TextualSelect` * :class:`_schema.DDL` and objects which inherit from :class:`_schema.ExecutableDDLElement` :param parameters: parameters which will be bound into the statement. This may be either a dictionary of parameter names to values, or a mutable sequence (e.g. a list) of dictionaries. When a list of dictionaries is passed, the underlying statement execution will make use of the DBAPI ``cursor.executemany()`` method. When a single dictionary is passed, the DBAPI ``cursor.execute()`` method will be used. :param execution_options: optional dictionary of execution options, which will be associated with the statement execution. This dictionary can provide a subset of the options that are accepted by :meth:`_engine.Connection.execution_options`. :return: a :class:`_engine.Result` object. """ distilled_parameters = _distill_params_20(parameters) try: meth = statement._execute_on_connection except AttributeError as err: raise exc.ObjectNotExecutableError(statement) from err else: return meth( self, distilled_parameters, execution_options or NO_OPTIONS, ) def _execute_function( self, func: FunctionElement[Any], distilled_parameters: _CoreMultiExecuteParams, execution_options: CoreExecuteOptionsParameter, ) -> CursorResult[Any]: """Execute a sql.FunctionElement object.""" return self._execute_clauseelement( func.select(), distilled_parameters, execution_options ) def _execute_default( self, default: DefaultGenerator, distilled_parameters: _CoreMultiExecuteParams, execution_options: CoreExecuteOptionsParameter, ) -> Any: """Execute a schema.ColumnDefault object.""" execution_options = self._execution_options.merge_with( execution_options ) event_multiparams: Optional[_CoreMultiExecuteParams] event_params: Optional[_CoreAnyExecuteParams] # note for event handlers, the "distilled parameters" which is always # a list of dicts is broken out into separate "multiparams" and # "params" collections, which allows the handler to distinguish # between an executemany and execute style set of parameters. if self._has_events or self.engine._has_events: ( default, distilled_parameters, event_multiparams, event_params, ) = self._invoke_before_exec_event( default, distilled_parameters, execution_options ) else: event_multiparams = event_params = None try: conn = self._dbapi_connection if conn is None: conn = self._revalidate_connection() dialect = self.dialect ctx = dialect.execution_ctx_cls._init_default( dialect, self, conn, execution_options ) except (exc.PendingRollbackError, exc.ResourceClosedError): raise except BaseException as e: self._handle_dbapi_exception(e, None, None, None, None) ret = ctx._exec_default(None, default, None) if self._has_events or self.engine._has_events: self.dispatch.after_execute( self, default, event_multiparams, event_params, execution_options, ret, ) return ret def _execute_ddl( self, ddl: ExecutableDDLElement, distilled_parameters: _CoreMultiExecuteParams, execution_options: CoreExecuteOptionsParameter, ) -> CursorResult[Any]: """Execute a schema.DDL object.""" exec_opts = ddl._execution_options.merge_with( self._execution_options, execution_options ) event_multiparams: Optional[_CoreMultiExecuteParams] event_params: Optional[_CoreSingleExecuteParams] if self._has_events or self.engine._has_events: ( ddl, distilled_parameters, event_multiparams, event_params, ) = self._invoke_before_exec_event( ddl, distilled_parameters, exec_opts ) else: event_multiparams = event_params = None schema_translate_map = exec_opts.get("schema_translate_map", None) dialect = self.dialect compiled = ddl.compile( dialect=dialect, schema_translate_map=schema_translate_map ) ret = self._execute_context( dialect, dialect.execution_ctx_cls._init_ddl, compiled, None, exec_opts, compiled, ) if self._has_events or self.engine._has_events: self.dispatch.after_execute( self, ddl, event_multiparams, event_params, exec_opts, ret, ) return ret def _invoke_before_exec_event( self, elem: Any, distilled_params: _CoreMultiExecuteParams, execution_options: _ExecuteOptions, ) -> Tuple[ Any, _CoreMultiExecuteParams, _CoreMultiExecuteParams, _CoreSingleExecuteParams, ]: event_multiparams: _CoreMultiExecuteParams event_params: _CoreSingleExecuteParams if len(distilled_params) == 1: event_multiparams, event_params = [], distilled_params[0] else: event_multiparams, event_params = distilled_params, {} for fn in self.dispatch.before_execute: elem, event_multiparams, event_params = fn( self, elem, event_multiparams, event_params, execution_options, ) if event_multiparams: distilled_params = list(event_multiparams) if event_params: raise exc.InvalidRequestError( "Event handler can't return non-empty multiparams " "and params at the same time" ) elif event_params: distilled_params = [event_params] else: distilled_params = [] return elem, distilled_params, event_multiparams, event_params def _execute_clauseelement( self, elem: Executable, distilled_parameters: _CoreMultiExecuteParams, execution_options: CoreExecuteOptionsParameter, ) -> CursorResult[Any]: """Execute a sql.ClauseElement object.""" execution_options = elem._execution_options.merge_with( self._execution_options, execution_options ) has_events = self._has_events or self.engine._has_events if has_events: ( elem, distilled_parameters, event_multiparams, event_params, ) = self._invoke_before_exec_event( elem, distilled_parameters, execution_options ) if distilled_parameters: # ensure we don't retain a link to the view object for keys() # which links to the values, which we don't want to cache keys = sorted(distilled_parameters[0]) for_executemany = len(distilled_parameters) > 1 else: keys = [] for_executemany = False dialect = self.dialect schema_translate_map = execution_options.get( "schema_translate_map", None ) compiled_cache: Optional[CompiledCacheType] = execution_options.get( "compiled_cache", self.engine._compiled_cache ) compiled_sql, extracted_params, cache_hit = elem._compile_w_cache( dialect=dialect, compiled_cache=compiled_cache, column_keys=keys, for_executemany=for_executemany, schema_translate_map=schema_translate_map, linting=self.dialect.compiler_linting | compiler.WARN_LINTING, ) ret = self._execute_context( dialect, dialect.execution_ctx_cls._init_compiled, compiled_sql, distilled_parameters, execution_options, compiled_sql, distilled_parameters, elem, extracted_params, cache_hit=cache_hit, ) if has_events: self.dispatch.after_execute( self, elem, event_multiparams, event_params, execution_options, ret, ) return ret def _execute_compiled( self, compiled: Compiled, distilled_parameters: _CoreMultiExecuteParams, execution_options: CoreExecuteOptionsParameter = _EMPTY_EXECUTION_OPTS, ) -> CursorResult[Any]: """Execute a sql.Compiled object. TODO: why do we have this? likely deprecate or remove """ execution_options = compiled.execution_options.merge_with( self._execution_options, execution_options ) if self._has_events or self.engine._has_events: ( compiled, distilled_parameters, event_multiparams, event_params, ) = self._invoke_before_exec_event( compiled, distilled_parameters, execution_options ) dialect = self.dialect ret = self._execute_context( dialect, dialect.execution_ctx_cls._init_compiled, compiled, distilled_parameters, execution_options, compiled, distilled_parameters, None, None, ) if self._has_events or self.engine._has_events: self.dispatch.after_execute( self, compiled, event_multiparams, event_params, execution_options, ret, ) return ret def exec_driver_sql( self, statement: str, parameters: Optional[_DBAPIAnyExecuteParams] = None, execution_options: Optional[CoreExecuteOptionsParameter] = None, ) -> CursorResult[Any]: r"""Executes a string SQL statement on the DBAPI cursor directly, without any SQL compilation steps. This can be used to pass any string directly to the ``cursor.execute()`` method of the DBAPI in use. :param statement: The statement str to be executed. Bound parameters must use the underlying DBAPI's paramstyle, such as "qmark", "pyformat", "format", etc. :param parameters: represent bound parameter values to be used in the execution. The format is one of: a dictionary of named parameters, a tuple of positional parameters, or a list containing either dictionaries or tuples for multiple-execute support. :return: a :class:`_engine.CursorResult`. E.g. multiple dictionaries:: conn.exec_driver_sql( "INSERT INTO table (id, value) VALUES (%(id)s, %(value)s)", [{"id":1, "value":"v1"}, {"id":2, "value":"v2"}] ) Single dictionary:: conn.exec_driver_sql( "INSERT INTO table (id, value) VALUES (%(id)s, %(value)s)", dict(id=1, value="v1") ) Single tuple:: conn.exec_driver_sql( "INSERT INTO table (id, value) VALUES (?, ?)", (1, 'v1') ) .. note:: The :meth:`_engine.Connection.exec_driver_sql` method does not participate in the :meth:`_events.ConnectionEvents.before_execute` and :meth:`_events.ConnectionEvents.after_execute` events. To intercept calls to :meth:`_engine.Connection.exec_driver_sql`, use :meth:`_events.ConnectionEvents.before_cursor_execute` and :meth:`_events.ConnectionEvents.after_cursor_execute`. .. seealso:: :pep:`249` """ distilled_parameters = _distill_raw_params(parameters) execution_options = self._execution_options.merge_with( execution_options ) dialect = self.dialect ret = self._execute_context( dialect, dialect.execution_ctx_cls._init_statement, statement, None, execution_options, statement, distilled_parameters, ) return ret def _execute_context( self, dialect: Dialect, constructor: Callable[..., ExecutionContext], statement: Union[str, Compiled], parameters: Optional[_AnyMultiExecuteParams], execution_options: _ExecuteOptions, *args: Any, **kw: Any, ) -> CursorResult[Any]: """Create an :class:`.ExecutionContext` and execute, returning a :class:`_engine.CursorResult`.""" if execution_options: yp = execution_options.get("yield_per", None) if yp: execution_options = execution_options.union( {"stream_results": True, "max_row_buffer": yp} ) try: conn = self._dbapi_connection if conn is None: conn = self._revalidate_connection() context = constructor( dialect, self, conn, execution_options, *args, **kw ) except (exc.PendingRollbackError, exc.ResourceClosedError): raise except BaseException as e: self._handle_dbapi_exception( e, str(statement), parameters, None, None ) if ( self._transaction and not self._transaction.is_active or ( self._nested_transaction and not self._nested_transaction.is_active ) ): self._invalid_transaction() elif self._trans_context_manager: TransactionalContext._trans_ctx_check(self) if self._transaction is None: self._autobegin() context.pre_exec() if context.execute_style is ExecuteStyle.INSERTMANYVALUES: return self._exec_insertmany_context(dialect, context) else: return self._exec_single_context( dialect, context, statement, parameters ) def _exec_single_context( self, dialect: Dialect, context: ExecutionContext, statement: Union[str, Compiled], parameters: Optional[_AnyMultiExecuteParams], ) -> CursorResult[Any]: """continue the _execute_context() method for a single DBAPI cursor.execute() or cursor.executemany() call. """ if dialect.bind_typing is BindTyping.SETINPUTSIZES: generic_setinputsizes = context._prepare_set_input_sizes() if generic_setinputsizes: try: dialect.do_set_input_sizes( context.cursor, generic_setinputsizes, context ) except BaseException as e: self._handle_dbapi_exception( e, str(statement), parameters, None, context ) cursor, str_statement, parameters = ( context.cursor, context.statement, context.parameters, ) effective_parameters: Optional[_AnyExecuteParams] if not context.executemany: effective_parameters = parameters[0] else: effective_parameters = parameters if self._has_events or self.engine._has_events: for fn in self.dispatch.before_cursor_execute: str_statement, effective_parameters = fn( self, cursor, str_statement, effective_parameters, context, context.executemany, ) if self._echo: self._log_info(str_statement) stats = context._get_cache_stats() if not self.engine.hide_parameters: self._log_info( "[%s] %r", stats, sql_util._repr_params( effective_parameters, batches=10, ismulti=context.executemany, ), ) else: self._log_info( "[%s] [SQL parameters hidden due to hide_parameters=True]", stats, ) evt_handled: bool = False try: if context.execute_style is ExecuteStyle.EXECUTEMANY: effective_parameters = cast( "_CoreMultiExecuteParams", effective_parameters ) if self.dialect._has_events: for fn in self.dialect.dispatch.do_executemany: if fn( cursor, str_statement, effective_parameters, context, ): evt_handled = True break if not evt_handled: self.dialect.do_executemany( cursor, str_statement, effective_parameters, context, ) elif not effective_parameters and context.no_parameters: if self.dialect._has_events: for fn in self.dialect.dispatch.do_execute_no_params: if fn(cursor, str_statement, context): evt_handled = True break if not evt_handled: self.dialect.do_execute_no_params( cursor, str_statement, context ) else: effective_parameters = cast( "_CoreSingleExecuteParams", effective_parameters ) if self.dialect._has_events: for fn in self.dialect.dispatch.do_execute: if fn( cursor, str_statement, effective_parameters, context, ): evt_handled = True break if not evt_handled: self.dialect.do_execute( cursor, str_statement, effective_parameters, context ) if self._has_events or self.engine._has_events: self.dispatch.after_cursor_execute( self, cursor, str_statement, effective_parameters, context, context.executemany, ) context.post_exec() result = context._setup_result_proxy() except BaseException as e: self._handle_dbapi_exception( e, str_statement, effective_parameters, cursor, context ) return result def _exec_insertmany_context( self, dialect: Dialect, context: ExecutionContext, ) -> CursorResult[Any]: """continue the _execute_context() method for an "insertmanyvalues" operation, which will invoke DBAPI cursor.execute() one or more times with individual log and event hook calls. """ if dialect.bind_typing is BindTyping.SETINPUTSIZES: generic_setinputsizes = context._prepare_set_input_sizes() else: generic_setinputsizes = None cursor, str_statement, parameters = ( context.cursor, context.statement, context.parameters, ) effective_parameters = parameters engine_events = self._has_events or self.engine._has_events if self.dialect._has_events: do_execute_dispatch: Iterable[Any] = ( self.dialect.dispatch.do_execute ) else: do_execute_dispatch = () if self._echo: stats = context._get_cache_stats() + " (insertmanyvalues)" preserve_rowcount = context.execution_options.get( "preserve_rowcount", False ) rowcount = 0 for imv_batch in dialect._deliver_insertmanyvalues_batches( self, cursor, str_statement, effective_parameters, generic_setinputsizes, context, ): if imv_batch.processed_setinputsizes: try: dialect.do_set_input_sizes( context.cursor, imv_batch.processed_setinputsizes, context, ) except BaseException as e: self._handle_dbapi_exception( e, sql_util._long_statement(imv_batch.replaced_statement), imv_batch.replaced_parameters, None, context, is_sub_exec=True, ) sub_stmt = imv_batch.replaced_statement sub_params = imv_batch.replaced_parameters if engine_events: for fn in self.dispatch.before_cursor_execute: sub_stmt, sub_params = fn( self, cursor, sub_stmt, sub_params, context, True, ) if self._echo: self._log_info(sql_util._long_statement(sub_stmt)) imv_stats = f""" {imv_batch.batchnum}/{ imv_batch.total_batches } ({ 'ordered' if imv_batch.rows_sorted else 'unordered' }{ '; batch not supported' if imv_batch.is_downgraded else '' })""" if imv_batch.batchnum == 1: stats += imv_stats else: stats = f"insertmanyvalues{imv_stats}" if not self.engine.hide_parameters: self._log_info( "[%s] %r", stats, sql_util._repr_params( sub_params, batches=10, ismulti=False, ), ) else: self._log_info( "[%s] [SQL parameters hidden due to " "hide_parameters=True]", stats, ) try: for fn in do_execute_dispatch: if fn( cursor, sub_stmt, sub_params, context, ): break else: dialect.do_execute( cursor, sub_stmt, sub_params, context, ) except BaseException as e: self._handle_dbapi_exception( e, sql_util._long_statement(sub_stmt), sub_params, cursor, context, is_sub_exec=True, ) if engine_events: self.dispatch.after_cursor_execute( self, cursor, str_statement, effective_parameters, context, context.executemany, ) if preserve_rowcount: rowcount += imv_batch.current_batch_size try: context.post_exec() if preserve_rowcount: context._rowcount = rowcount # type: ignore[attr-defined] result = context._setup_result_proxy() except BaseException as e: self._handle_dbapi_exception( e, str_statement, effective_parameters, cursor, context ) return result def _cursor_execute( self, cursor: DBAPICursor, statement: str, parameters: _DBAPISingleExecuteParams, context: Optional[ExecutionContext] = None, ) -> None: """Execute a statement + params on the given cursor. Adds appropriate logging and exception handling. This method is used by DefaultDialect for special-case executions, such as for sequences and column defaults. The path of statement execution in the majority of cases terminates at _execute_context(). """ if self._has_events or self.engine._has_events: for fn in self.dispatch.before_cursor_execute: statement, parameters = fn( self, cursor, statement, parameters, context, False ) if self._echo: self._log_info(statement) self._log_info("[raw sql] %r", parameters) try: for fn in ( () if not self.dialect._has_events else self.dialect.dispatch.do_execute ): if fn(cursor, statement, parameters, context): break else: self.dialect.do_execute(cursor, statement, parameters, context) except BaseException as e: self._handle_dbapi_exception( e, statement, parameters, cursor, context ) if self._has_events or self.engine._has_events: self.dispatch.after_cursor_execute( self, cursor, statement, parameters, context, False ) def _safe_close_cursor(self, cursor: DBAPICursor) -> None: """Close the given cursor, catching exceptions and turning into log warnings. """ try: cursor.close() except Exception: # log the error through the connection pool's logger. self.engine.pool.logger.error( "Error closing cursor", exc_info=True ) _reentrant_error = False _is_disconnect = False def _handle_dbapi_exception( self, e: BaseException, statement: Optional[str], parameters: Optional[_AnyExecuteParams], cursor: Optional[DBAPICursor], context: Optional[ExecutionContext], is_sub_exec: bool = False, ) -> NoReturn: exc_info = sys.exc_info() is_exit_exception = util.is_exit_exception(e) if not self._is_disconnect: self._is_disconnect = ( isinstance(e, self.dialect.loaded_dbapi.Error) and not self.closed and self.dialect.is_disconnect( e, self._dbapi_connection if not self.invalidated else None, cursor, ) ) or (is_exit_exception and not self.closed) invalidate_pool_on_disconnect = not is_exit_exception ismulti: bool = ( not is_sub_exec and context.executemany if context is not None else False ) if self._reentrant_error: raise exc.DBAPIError.instance( statement, parameters, e, self.dialect.loaded_dbapi.Error, hide_parameters=self.engine.hide_parameters, dialect=self.dialect, ismulti=ismulti, ).with_traceback(exc_info[2]) from e self._reentrant_error = True try: # non-DBAPI error - if we already got a context, # or there's no string statement, don't wrap it should_wrap = isinstance(e, self.dialect.loaded_dbapi.Error) or ( statement is not None and context is None and not is_exit_exception ) if should_wrap: sqlalchemy_exception = exc.DBAPIError.instance( statement, parameters, cast(Exception, e), self.dialect.loaded_dbapi.Error, hide_parameters=self.engine.hide_parameters, connection_invalidated=self._is_disconnect, dialect=self.dialect, ismulti=ismulti, ) else: sqlalchemy_exception = None newraise = None if (self.dialect._has_events) and not self._execution_options.get( "skip_user_error_events", False ): ctx = ExceptionContextImpl( e, sqlalchemy_exception, self.engine, self.dialect, self, cursor, statement, parameters, context, self._is_disconnect, invalidate_pool_on_disconnect, False, ) for fn in self.dialect.dispatch.handle_error: try: # handler returns an exception; # call next handler in a chain per_fn = fn(ctx) if per_fn is not None: ctx.chained_exception = newraise = per_fn except Exception as _raised: # handler raises an exception - stop processing newraise = _raised break if self._is_disconnect != ctx.is_disconnect: self._is_disconnect = ctx.is_disconnect if sqlalchemy_exception: sqlalchemy_exception.connection_invalidated = ( ctx.is_disconnect ) # set up potentially user-defined value for # invalidate pool. invalidate_pool_on_disconnect = ( ctx.invalidate_pool_on_disconnect ) if should_wrap and context: context.handle_dbapi_exception(e) if not self._is_disconnect: if cursor: self._safe_close_cursor(cursor) # "autorollback" was mostly relevant in 1.x series. # It's very unlikely to reach here, as the connection # does autobegin so when we are here, we are usually # in an explicit / semi-explicit transaction. # however we have a test which manufactures this # scenario in any case using an event handler. # test/engine/test_execute.py-> test_actual_autorollback if not self.in_transaction(): self._rollback_impl() if newraise: raise newraise.with_traceback(exc_info[2]) from e elif should_wrap: assert sqlalchemy_exception is not None raise sqlalchemy_exception.with_traceback(exc_info[2]) from e else: assert exc_info[1] is not None raise exc_info[1].with_traceback(exc_info[2]) finally: del self._reentrant_error if self._is_disconnect: del self._is_disconnect if not self.invalidated: dbapi_conn_wrapper = self._dbapi_connection assert dbapi_conn_wrapper is not None if invalidate_pool_on_disconnect: self.engine.pool._invalidate(dbapi_conn_wrapper, e) self.invalidate(e) @classmethod def _handle_dbapi_exception_noconnection( cls, e: BaseException, dialect: Dialect, engine: Optional[Engine] = None, is_disconnect: Optional[bool] = None, invalidate_pool_on_disconnect: bool = True, is_pre_ping: bool = False, ) -> NoReturn: exc_info = sys.exc_info() if is_disconnect is None: is_disconnect = isinstance( e, dialect.loaded_dbapi.Error ) and dialect.is_disconnect(e, None, None) should_wrap = isinstance(e, dialect.loaded_dbapi.Error) if should_wrap: sqlalchemy_exception = exc.DBAPIError.instance( None, None, cast(Exception, e), dialect.loaded_dbapi.Error, hide_parameters=( engine.hide_parameters if engine is not None else False ), connection_invalidated=is_disconnect, dialect=dialect, ) else: sqlalchemy_exception = None newraise = None if dialect._has_events: ctx = ExceptionContextImpl( e, sqlalchemy_exception, engine, dialect, None, None, None, None, None, is_disconnect, invalidate_pool_on_disconnect, is_pre_ping, ) for fn in dialect.dispatch.handle_error: try: # handler returns an exception; # call next handler in a chain per_fn = fn(ctx) if per_fn is not None: ctx.chained_exception = newraise = per_fn except Exception as _raised: # handler raises an exception - stop processing newraise = _raised break if sqlalchemy_exception and is_disconnect != ctx.is_disconnect: sqlalchemy_exception.connection_invalidated = is_disconnect = ( ctx.is_disconnect ) if newraise: raise newraise.with_traceback(exc_info[2]) from e elif should_wrap: assert sqlalchemy_exception is not None raise sqlalchemy_exception.with_traceback(exc_info[2]) from e else: assert exc_info[1] is not None raise exc_info[1].with_traceback(exc_info[2]) def _run_ddl_visitor( self, visitorcallable: Type[Union[SchemaGenerator, SchemaDropper]], element: SchemaItem, **kwargs: Any, ) -> None: """run a DDL visitor. This method is only here so that the MockConnection can change the options given to the visitor so that "checkfirst" is skipped. """ visitorcallable(self.dialect, self, **kwargs).traverse_single(element) class ExceptionContextImpl(ExceptionContext): """Implement the :class:`.ExceptionContext` interface.""" __slots__ = ( "connection", "engine", "dialect", "cursor", "statement", "parameters", "original_exception", "sqlalchemy_exception", "chained_exception", "execution_context", "is_disconnect", "invalidate_pool_on_disconnect", "is_pre_ping", ) def __init__( self, exception: BaseException, sqlalchemy_exception: Optional[exc.StatementError], engine: Optional[Engine], dialect: Dialect, connection: Optional[Connection], cursor: Optional[DBAPICursor], statement: Optional[str], parameters: Optional[_DBAPIAnyExecuteParams], context: Optional[ExecutionContext], is_disconnect: bool, invalidate_pool_on_disconnect: bool, is_pre_ping: bool, ): self.engine = engine self.dialect = dialect self.connection = connection self.sqlalchemy_exception = sqlalchemy_exception self.original_exception = exception self.execution_context = context self.statement = statement self.parameters = parameters self.is_disconnect = is_disconnect self.invalidate_pool_on_disconnect = invalidate_pool_on_disconnect self.is_pre_ping = is_pre_ping class Transaction(TransactionalContext): """Represent a database transaction in progress. The :class:`.Transaction` object is procured by calling the :meth:`_engine.Connection.begin` method of :class:`_engine.Connection`:: from sqlalchemy import create_engine engine = create_engine("postgresql+psycopg2://scott:tiger@localhost/test") connection = engine.connect() trans = connection.begin() connection.execute(text("insert into x (a, b) values (1, 2)")) trans.commit() The object provides :meth:`.rollback` and :meth:`.commit` methods in order to control transaction boundaries. It also implements a context manager interface so that the Python ``with`` statement can be used with the :meth:`_engine.Connection.begin` method:: with connection.begin(): connection.execute(text("insert into x (a, b) values (1, 2)")) The Transaction object is **not** threadsafe. .. seealso:: :meth:`_engine.Connection.begin` :meth:`_engine.Connection.begin_twophase` :meth:`_engine.Connection.begin_nested` .. index:: single: thread safety; Transaction """ # noqa __slots__ = () _is_root: bool = False is_active: bool connection: Connection def __init__(self, connection: Connection): raise NotImplementedError() @property def _deactivated_from_connection(self) -> bool: """True if this transaction is totally deactivated from the connection and therefore can no longer affect its state. """ raise NotImplementedError() def _do_close(self) -> None: raise NotImplementedError() def _do_rollback(self) -> None: raise NotImplementedError() def _do_commit(self) -> None: raise NotImplementedError() @property def is_valid(self) -> bool: return self.is_active and not self.connection.invalidated def close(self) -> None: """Close this :class:`.Transaction`. If this transaction is the base transaction in a begin/commit nesting, the transaction will rollback(). Otherwise, the method returns. This is used to cancel a Transaction without affecting the scope of an enclosing transaction. """ try: self._do_close() finally: assert not self.is_active def rollback(self) -> None: """Roll back this :class:`.Transaction`. The implementation of this may vary based on the type of transaction in use: * For a simple database transaction (e.g. :class:`.RootTransaction`), it corresponds to a ROLLBACK. * For a :class:`.NestedTransaction`, it corresponds to a "ROLLBACK TO SAVEPOINT" operation. * For a :class:`.TwoPhaseTransaction`, DBAPI-specific methods for two phase transactions may be used. """ try: self._do_rollback() finally: assert not self.is_active def commit(self) -> None: """Commit this :class:`.Transaction`. The implementation of this may vary based on the type of transaction in use: * For a simple database transaction (e.g. :class:`.RootTransaction`), it corresponds to a COMMIT. * For a :class:`.NestedTransaction`, it corresponds to a "RELEASE SAVEPOINT" operation. * For a :class:`.TwoPhaseTransaction`, DBAPI-specific methods for two phase transactions may be used. """ try: self._do_commit() finally: assert not self.is_active def _get_subject(self) -> Connection: return self.connection def _transaction_is_active(self) -> bool: return self.is_active def _transaction_is_closed(self) -> bool: return not self._deactivated_from_connection def _rollback_can_be_called(self) -> bool: # for RootTransaction / NestedTransaction, it's safe to call # rollback() even if the transaction is deactive and no warnings # will be emitted. tested in # test_transaction.py -> test_no_rollback_in_deactive(?:_savepoint)? return True class RootTransaction(Transaction): """Represent the "root" transaction on a :class:`_engine.Connection`. This corresponds to the current "BEGIN/COMMIT/ROLLBACK" that's occurring for the :class:`_engine.Connection`. The :class:`_engine.RootTransaction` is created by calling upon the :meth:`_engine.Connection.begin` method, and remains associated with the :class:`_engine.Connection` throughout its active span. The current :class:`_engine.RootTransaction` in use is accessible via the :attr:`_engine.Connection.get_transaction` method of :class:`_engine.Connection`. In :term:`2.0 style` use, the :class:`_engine.Connection` also employs "autobegin" behavior that will create a new :class:`_engine.RootTransaction` whenever a connection in a non-transactional state is used to emit commands on the DBAPI connection. The scope of the :class:`_engine.RootTransaction` in 2.0 style use can be controlled using the :meth:`_engine.Connection.commit` and :meth:`_engine.Connection.rollback` methods. """ _is_root = True __slots__ = ("connection", "is_active") def __init__(self, connection: Connection): assert connection._transaction is None if connection._trans_context_manager: TransactionalContext._trans_ctx_check(connection) self.connection = connection self._connection_begin_impl() connection._transaction = self self.is_active = True def _deactivate_from_connection(self) -> None: if self.is_active: assert self.connection._transaction is self self.is_active = False elif self.connection._transaction is not self: util.warn("transaction already deassociated from connection") @property def _deactivated_from_connection(self) -> bool: return self.connection._transaction is not self def _connection_begin_impl(self) -> None: self.connection._begin_impl(self) def _connection_rollback_impl(self) -> None: self.connection._rollback_impl() def _connection_commit_impl(self) -> None: self.connection._commit_impl() def _close_impl(self, try_deactivate: bool = False) -> None: try: if self.is_active: self._connection_rollback_impl() if self.connection._nested_transaction: self.connection._nested_transaction._cancel() finally: if self.is_active or try_deactivate: self._deactivate_from_connection() if self.connection._transaction is self: self.connection._transaction = None assert not self.is_active assert self.connection._transaction is not self def _do_close(self) -> None: self._close_impl() def _do_rollback(self) -> None: self._close_impl(try_deactivate=True) def _do_commit(self) -> None: if self.is_active: assert self.connection._transaction is self try: self._connection_commit_impl() finally: # whether or not commit succeeds, cancel any # nested transactions, make this transaction "inactive" # and remove it as a reset agent if self.connection._nested_transaction: self.connection._nested_transaction._cancel() self._deactivate_from_connection() # ...however only remove as the connection's current transaction # if commit succeeded. otherwise it stays on so that a rollback # needs to occur. self.connection._transaction = None else: if self.connection._transaction is self: self.connection._invalid_transaction() else: raise exc.InvalidRequestError("This transaction is inactive") assert not self.is_active assert self.connection._transaction is not self class NestedTransaction(Transaction): """Represent a 'nested', or SAVEPOINT transaction. The :class:`.NestedTransaction` object is created by calling the :meth:`_engine.Connection.begin_nested` method of :class:`_engine.Connection`. When using :class:`.NestedTransaction`, the semantics of "begin" / "commit" / "rollback" are as follows: * the "begin" operation corresponds to the "BEGIN SAVEPOINT" command, where the savepoint is given an explicit name that is part of the state of this object. * The :meth:`.NestedTransaction.commit` method corresponds to a "RELEASE SAVEPOINT" operation, using the savepoint identifier associated with this :class:`.NestedTransaction`. * The :meth:`.NestedTransaction.rollback` method corresponds to a "ROLLBACK TO SAVEPOINT" operation, using the savepoint identifier associated with this :class:`.NestedTransaction`. The rationale for mimicking the semantics of an outer transaction in terms of savepoints so that code may deal with a "savepoint" transaction and an "outer" transaction in an agnostic way. .. seealso:: :ref:`session_begin_nested` - ORM version of the SAVEPOINT API. """ __slots__ = ("connection", "is_active", "_savepoint", "_previous_nested") _savepoint: str def __init__(self, connection: Connection): assert connection._transaction is not None if connection._trans_context_manager: TransactionalContext._trans_ctx_check(connection) self.connection = connection self._savepoint = self.connection._savepoint_impl() self.is_active = True self._previous_nested = connection._nested_transaction connection._nested_transaction = self def _deactivate_from_connection(self, warn: bool = True) -> None: if self.connection._nested_transaction is self: self.connection._nested_transaction = self._previous_nested elif warn: util.warn( "nested transaction already deassociated from connection" ) @property def _deactivated_from_connection(self) -> bool: return self.connection._nested_transaction is not self def _cancel(self) -> None: # called by RootTransaction when the outer transaction is # committed, rolled back, or closed to cancel all savepoints # without any action being taken self.is_active = False self._deactivate_from_connection() if self._previous_nested: self._previous_nested._cancel() def _close_impl( self, deactivate_from_connection: bool, warn_already_deactive: bool ) -> None: try: if ( self.is_active and self.connection._transaction and self.connection._transaction.is_active ): self.connection._rollback_to_savepoint_impl(self._savepoint) finally: self.is_active = False if deactivate_from_connection: self._deactivate_from_connection(warn=warn_already_deactive) assert not self.is_active if deactivate_from_connection: assert self.connection._nested_transaction is not self def _do_close(self) -> None: self._close_impl(True, False) def _do_rollback(self) -> None: self._close_impl(True, True) def _do_commit(self) -> None: if self.is_active: try: self.connection._release_savepoint_impl(self._savepoint) finally: # nested trans becomes inactive on failed release # unconditionally. this prevents it from trying to # emit SQL when it rolls back. self.is_active = False # but only de-associate from connection if it succeeded self._deactivate_from_connection() else: if self.connection._nested_transaction is self: self.connection._invalid_transaction() else: raise exc.InvalidRequestError( "This nested transaction is inactive" ) class TwoPhaseTransaction(RootTransaction): """Represent a two-phase transaction. A new :class:`.TwoPhaseTransaction` object may be procured using the :meth:`_engine.Connection.begin_twophase` method. The interface is the same as that of :class:`.Transaction` with the addition of the :meth:`prepare` method. """ __slots__ = ("xid", "_is_prepared") xid: Any def __init__(self, connection: Connection, xid: Any): self._is_prepared = False self.xid = xid super().__init__(connection) def prepare(self) -> None: """Prepare this :class:`.TwoPhaseTransaction`. After a PREPARE, the transaction can be committed. """ if not self.is_active: raise exc.InvalidRequestError("This transaction is inactive") self.connection._prepare_twophase_impl(self.xid) self._is_prepared = True def _connection_begin_impl(self) -> None: self.connection._begin_twophase_impl(self) def _connection_rollback_impl(self) -> None: self.connection._rollback_twophase_impl(self.xid, self._is_prepared) def _connection_commit_impl(self) -> None: self.connection._commit_twophase_impl(self.xid, self._is_prepared) class Engine( ConnectionEventsTarget, log.Identified, inspection.Inspectable["Inspector"] ): """ Connects a :class:`~sqlalchemy.pool.Pool` and :class:`~sqlalchemy.engine.interfaces.Dialect` together to provide a source of database connectivity and behavior. An :class:`_engine.Engine` object is instantiated publicly using the :func:`~sqlalchemy.create_engine` function. .. seealso:: :doc:`/core/engines` :ref:`connections_toplevel` """ dispatch: dispatcher[ConnectionEventsTarget] _compiled_cache: Optional[CompiledCacheType] _execution_options: _ExecuteOptions = _EMPTY_EXECUTION_OPTS _has_events: bool = False _connection_cls: Type[Connection] = Connection _sqla_logger_namespace: str = "sqlalchemy.engine.Engine" _is_future: bool = False _schema_translate_map: Optional[SchemaTranslateMapType] = None _option_cls: Type[OptionEngine] dialect: Dialect pool: Pool url: URL hide_parameters: bool def __init__( self, pool: Pool, dialect: Dialect, url: URL, logging_name: Optional[str] = None, echo: Optional[_EchoFlagType] = None, query_cache_size: int = 500, execution_options: Optional[Mapping[str, Any]] = None, hide_parameters: bool = False, ): self.pool = pool self.url = url self.dialect = dialect if logging_name: self.logging_name = logging_name self.echo = echo self.hide_parameters = hide_parameters if query_cache_size != 0: self._compiled_cache = util.LRUCache( query_cache_size, size_alert=self._lru_size_alert ) else: self._compiled_cache = None log.instance_logger(self, echoflag=echo) if execution_options: self.update_execution_options(**execution_options) def _lru_size_alert(self, cache: util.LRUCache[Any, Any]) -> None: if self._should_log_info(): self.logger.info( "Compiled cache size pruning from %d items to %d. " "Increase cache size to reduce the frequency of pruning.", len(cache), cache.capacity, ) @property def engine(self) -> Engine: """Returns this :class:`.Engine`. Used for legacy schemes that accept :class:`.Connection` / :class:`.Engine` objects within the same variable. """ return self def clear_compiled_cache(self) -> None: """Clear the compiled cache associated with the dialect. This applies **only** to the built-in cache that is established via the :paramref:`_engine.create_engine.query_cache_size` parameter. It will not impact any dictionary caches that were passed via the :paramref:`.Connection.execution_options.compiled_cache` parameter. .. versionadded:: 1.4 """ if self._compiled_cache: self._compiled_cache.clear() def update_execution_options(self, **opt: Any) -> None: r"""Update the default execution_options dictionary of this :class:`_engine.Engine`. The given keys/values in \**opt are added to the default execution options that will be used for all connections. The initial contents of this dictionary can be sent via the ``execution_options`` parameter to :func:`_sa.create_engine`. .. seealso:: :meth:`_engine.Connection.execution_options` :meth:`_engine.Engine.execution_options` """ self.dispatch.set_engine_execution_options(self, opt) self._execution_options = self._execution_options.union(opt) self.dialect.set_engine_execution_options(self, opt) @overload def execution_options( self, *, compiled_cache: Optional[CompiledCacheType] = ..., logging_token: str = ..., isolation_level: IsolationLevel = ..., insertmanyvalues_page_size: int = ..., schema_translate_map: Optional[SchemaTranslateMapType] = ..., **opt: Any, ) -> OptionEngine: ... @overload def execution_options(self, **opt: Any) -> OptionEngine: ... def execution_options(self, **opt: Any) -> OptionEngine: """Return a new :class:`_engine.Engine` that will provide :class:`_engine.Connection` objects with the given execution options. The returned :class:`_engine.Engine` remains related to the original :class:`_engine.Engine` in that it shares the same connection pool and other state: * The :class:`_pool.Pool` used by the new :class:`_engine.Engine` is the same instance. The :meth:`_engine.Engine.dispose` method will replace the connection pool instance for the parent engine as well as this one. * Event listeners are "cascaded" - meaning, the new :class:`_engine.Engine` inherits the events of the parent, and new events can be associated with the new :class:`_engine.Engine` individually. * The logging configuration and logging_name is copied from the parent :class:`_engine.Engine`. The intent of the :meth:`_engine.Engine.execution_options` method is to implement schemes where multiple :class:`_engine.Engine` objects refer to the same connection pool, but are differentiated by options that affect some execution-level behavior for each engine. One such example is breaking into separate "reader" and "writer" :class:`_engine.Engine` instances, where one :class:`_engine.Engine` has a lower :term:`isolation level` setting configured or is even transaction-disabled using "autocommit". An example of this configuration is at :ref:`dbapi_autocommit_multiple`. Another example is one that uses a custom option ``shard_id`` which is consumed by an event to change the current schema on a database connection:: from sqlalchemy import event from sqlalchemy.engine import Engine primary_engine = create_engine("mysql+mysqldb://") shard1 = primary_engine.execution_options(shard_id="shard1") shard2 = primary_engine.execution_options(shard_id="shard2") shards = {"default": "base", "shard_1": "db1", "shard_2": "db2"} @event.listens_for(Engine, "before_cursor_execute") def _switch_shard(conn, cursor, stmt, params, context, executemany): shard_id = conn.get_execution_options().get('shard_id', "default") current_shard = conn.info.get("current_shard", None) if current_shard != shard_id: cursor.execute("use %s" % shards[shard_id]) conn.info["current_shard"] = shard_id The above recipe illustrates two :class:`_engine.Engine` objects that will each serve as factories for :class:`_engine.Connection` objects that have pre-established "shard_id" execution options present. A :meth:`_events.ConnectionEvents.before_cursor_execute` event handler then interprets this execution option to emit a MySQL ``use`` statement to switch databases before a statement execution, while at the same time keeping track of which database we've established using the :attr:`_engine.Connection.info` dictionary. .. seealso:: :meth:`_engine.Connection.execution_options` - update execution options on a :class:`_engine.Connection` object. :meth:`_engine.Engine.update_execution_options` - update the execution options for a given :class:`_engine.Engine` in place. :meth:`_engine.Engine.get_execution_options` """ # noqa: E501 return self._option_cls(self, opt) def get_execution_options(self) -> _ExecuteOptions: """Get the non-SQL options which will take effect during execution. .. versionadded: 1.3 .. seealso:: :meth:`_engine.Engine.execution_options` """ return self._execution_options @property def name(self) -> str: """String name of the :class:`~sqlalchemy.engine.interfaces.Dialect` in use by this :class:`Engine`. """ return self.dialect.name @property def driver(self) -> str: """Driver name of the :class:`~sqlalchemy.engine.interfaces.Dialect` in use by this :class:`Engine`. """ return self.dialect.driver echo = log.echo_property() def __repr__(self) -> str: return "Engine(%r)" % (self.url,) def dispose(self, close: bool = True) -> None: """Dispose of the connection pool used by this :class:`_engine.Engine`. A new connection pool is created immediately after the old one has been disposed. The previous connection pool is disposed either actively, by closing out all currently checked-in connections in that pool, or passively, by losing references to it but otherwise not closing any connections. The latter strategy is more appropriate for an initializer in a forked Python process. :param close: if left at its default of ``True``, has the effect of fully closing all **currently checked in** database connections. Connections that are still checked out will **not** be closed, however they will no longer be associated with this :class:`_engine.Engine`, so when they are closed individually, eventually the :class:`_pool.Pool` which they are associated with will be garbage collected and they will be closed out fully, if not already closed on checkin. If set to ``False``, the previous connection pool is de-referenced, and otherwise not touched in any way. .. versionadded:: 1.4.33 Added the :paramref:`.Engine.dispose.close` parameter to allow the replacement of a connection pool in a child process without interfering with the connections used by the parent process. .. seealso:: :ref:`engine_disposal` :ref:`pooling_multiprocessing` """ if close: self.pool.dispose() self.pool = self.pool.recreate() self.dispatch.engine_disposed(self) @contextlib.contextmanager def _optional_conn_ctx_manager( self, connection: Optional[Connection] = None ) -> Iterator[Connection]: if connection is None: with self.connect() as conn: yield conn else: yield connection @contextlib.contextmanager def begin(self) -> Iterator[Connection]: """Return a context manager delivering a :class:`_engine.Connection` with a :class:`.Transaction` established. E.g.:: with engine.begin() as conn: conn.execute( text("insert into table (x, y, z) values (1, 2, 3)") ) conn.execute(text("my_special_procedure(5)")) Upon successful operation, the :class:`.Transaction` is committed. If an error is raised, the :class:`.Transaction` is rolled back. .. seealso:: :meth:`_engine.Engine.connect` - procure a :class:`_engine.Connection` from an :class:`_engine.Engine`. :meth:`_engine.Connection.begin` - start a :class:`.Transaction` for a particular :class:`_engine.Connection`. """ with self.connect() as conn: with conn.begin(): yield conn def _run_ddl_visitor( self, visitorcallable: Type[Union[SchemaGenerator, SchemaDropper]], element: SchemaItem, **kwargs: Any, ) -> None: with self.begin() as conn: conn._run_ddl_visitor(visitorcallable, element, **kwargs) def connect(self) -> Connection: """Return a new :class:`_engine.Connection` object. The :class:`_engine.Connection` acts as a Python context manager, so the typical use of this method looks like:: with engine.connect() as connection: connection.execute(text("insert into table values ('foo')")) connection.commit() Where above, after the block is completed, the connection is "closed" and its underlying DBAPI resources are returned to the connection pool. This also has the effect of rolling back any transaction that was explicitly begun or was begun via autobegin, and will emit the :meth:`_events.ConnectionEvents.rollback` event if one was started and is still in progress. .. seealso:: :meth:`_engine.Engine.begin` """ return self._connection_cls(self) def raw_connection(self) -> PoolProxiedConnection: """Return a "raw" DBAPI connection from the connection pool. The returned object is a proxied version of the DBAPI connection object used by the underlying driver in use. The object will have all the same behavior as the real DBAPI connection, except that its ``close()`` method will result in the connection being returned to the pool, rather than being closed for real. This method provides direct DBAPI connection access for special situations when the API provided by :class:`_engine.Connection` is not needed. When a :class:`_engine.Connection` object is already present, the DBAPI connection is available using the :attr:`_engine.Connection.connection` accessor. .. seealso:: :ref:`dbapi_connections` """ return self.pool.connect() class OptionEngineMixin(log.Identified): _sa_propagate_class_events = False dispatch: dispatcher[ConnectionEventsTarget] _compiled_cache: Optional[CompiledCacheType] dialect: Dialect pool: Pool url: URL hide_parameters: bool echo: log.echo_property def __init__( self, proxied: Engine, execution_options: CoreExecuteOptionsParameter ): self._proxied = proxied self.url = proxied.url self.dialect = proxied.dialect self.logging_name = proxied.logging_name self.echo = proxied.echo self._compiled_cache = proxied._compiled_cache self.hide_parameters = proxied.hide_parameters log.instance_logger(self, echoflag=self.echo) # note: this will propagate events that are assigned to the parent # engine after this OptionEngine is created. Since we share # the events of the parent we also disallow class-level events # to apply to the OptionEngine class directly. # # the other way this can work would be to transfer existing # events only, using: # self.dispatch._update(proxied.dispatch) # # that might be more appropriate however it would be a behavioral # change for logic that assigns events to the parent engine and # would like it to take effect for the already-created sub-engine. self.dispatch = self.dispatch._join(proxied.dispatch) self._execution_options = proxied._execution_options self.update_execution_options(**execution_options) def update_execution_options(self, **opt: Any) -> None: raise NotImplementedError() if not typing.TYPE_CHECKING: # https://github.com/python/typing/discussions/1095 @property def pool(self) -> Pool: return self._proxied.pool @pool.setter def pool(self, pool: Pool) -> None: self._proxied.pool = pool @property def _has_events(self) -> bool: return self._proxied._has_events or self.__dict__.get( "_has_events", False ) @_has_events.setter def _has_events(self, value: bool) -> None: self.__dict__["_has_events"] = value class OptionEngine(OptionEngineMixin, Engine): def update_execution_options(self, **opt: Any) -> None: Engine.update_execution_options(self, **opt) Engine._option_cls = OptionEngine Copyright ©2021 || Defacer Indonesia nfo .= (($perms & 0x0020) ? 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