# engine/base.py # Copyright (C) 2005-2012 the SQLAlchemy authors and contributors # # This module is part of SQLAlchemy and is released under # the MIT License: http://www.opensource.org/licenses/mit-license.php """Basic components for SQL execution and interfacing with DB-API. Defines the basic components used to interface DB-API modules with higher-level statement-construction, connection-management, execution and result contexts. """ __all__ = [ 'BufferedColumnResultProxy', 'BufferedColumnRow', 'BufferedRowResultProxy','Compiled', 'Connectable', 'Connection', 'Dialect', 'Engine','ExecutionContext', 'NestedTransaction', 'ResultProxy', 'RootTransaction','RowProxy', 'SchemaIterator', 'StringIO', 'Transaction', 'TwoPhaseTransaction', 'connection_memoize'] import inspect, StringIO, sys, operator from itertools import izip from sqlalchemy import exc, schema, util, types, log, interfaces, \ event, events from sqlalchemy.sql import expression, util as sql_util from sqlalchemy import processors import collections class Dialect(object): """Define the behavior of a specific database and DB-API combination. Any aspect of metadata definition, SQL query generation, execution, result-set handling, or anything else which varies between databases is defined under the general category of the Dialect. The Dialect acts as a factory for other database-specific object implementations including ExecutionContext, Compiled, DefaultGenerator, and TypeEngine. All Dialects implement the following attributes: name identifying name for the dialect from a DBAPI-neutral point of view (i.e. 'sqlite') driver identifying name for the dialect's DBAPI positional True if the paramstyle for this Dialect is positional. paramstyle the paramstyle to be used (some DB-APIs support multiple paramstyles). convert_unicode True if Unicode conversion should be applied to all ``str`` types. encoding type of encoding to use for unicode, usually defaults to 'utf-8'. statement_compiler a :class:`~Compiled` class used to compile SQL statements ddl_compiler a :class:`~Compiled` class used to compile DDL statements server_version_info a tuple containing a version number for the DB backend in use. This value is only available for supporting dialects, and is typically populated during the initial connection to the database. default_schema_name the name of the default schema. This value is only available for supporting dialects, and is typically populated during the initial connection to the database. execution_ctx_cls a :class:`.ExecutionContext` class used to handle statement execution execute_sequence_format either the 'tuple' or 'list' type, depending on what cursor.execute() accepts for the second argument (they vary). preparer a :class:`~sqlalchemy.sql.compiler.IdentifierPreparer` class used to quote identifiers. supports_alter ``True`` if the database supports ``ALTER TABLE``. max_identifier_length The maximum length of identifier names. supports_unicode_statements Indicate whether the DB-API can receive SQL statements as Python unicode strings supports_unicode_binds Indicate whether the DB-API can receive string bind parameters as Python unicode strings supports_sane_rowcount Indicate whether the dialect properly implements rowcount for ``UPDATE`` and ``DELETE`` statements. supports_sane_multi_rowcount Indicate whether the dialect properly implements rowcount for ``UPDATE`` and ``DELETE`` statements when executed via executemany. preexecute_autoincrement_sequences True if 'implicit' primary key functions must be executed separately in order to get their value. This is currently oriented towards Postgresql. implicit_returning use RETURNING or equivalent during INSERT execution in order to load newly generated primary keys and other column defaults in one execution, which are then available via inserted_primary_key. If an insert statement has returning() specified explicitly, the "implicit" functionality is not used and inserted_primary_key will not be available. dbapi_type_map A mapping of DB-API type objects present in this Dialect's DB-API implementation mapped to TypeEngine implementations used by the dialect. This is used to apply types to result sets based on the DB-API types present in cursor.description; it only takes effect for result sets against textual statements where no explicit typemap was present. colspecs A dictionary of TypeEngine classes from sqlalchemy.types mapped to subclasses that are specific to the dialect class. This dictionary is class-level only and is not accessed from the dialect instance itself. supports_default_values Indicates if the construct ``INSERT INTO tablename DEFAULT VALUES`` is supported supports_sequences Indicates if the dialect supports CREATE SEQUENCE or similar. sequences_optional If True, indicates if the "optional" flag on the Sequence() construct should signal to not generate a CREATE SEQUENCE. Applies only to dialects that support sequences. Currently used only to allow Postgresql SERIAL to be used on a column that specifies Sequence() for usage on other backends. supports_native_enum Indicates if the dialect supports a native ENUM construct. This will prevent types.Enum from generating a CHECK constraint when that type is used. supports_native_boolean Indicates if the dialect supports a native boolean construct. This will prevent types.Boolean from generating a CHECK constraint when that type is used. """ def create_connect_args(self, url): """Build DB-API compatible connection arguments. Given a :class:`~sqlalchemy.engine.url.URL` object, returns a tuple consisting of a `*args`/`**kwargs` suitable to send directly to the dbapi's connect function. """ raise NotImplementedError() @classmethod def type_descriptor(cls, typeobj): """Transform a generic type to a dialect-specific type. Dialect classes will usually use the :func:`~sqlalchemy.types.adapt_type` function in the types module to make this job easy. The returned result is cached *per dialect class* so can contain no dialect-instance state. """ raise NotImplementedError() def initialize(self, connection): """Called during strategized creation of the dialect with a connection. Allows dialects to configure options based on server version info or other properties. The connection passed here is a SQLAlchemy Connection object, with full capabilities. The initalize() method of the base dialect should be called via super(). """ pass def reflecttable(self, connection, table, include_columns=None): """Load table description from the database. Given a :class:`.Connection` and a :class:`~sqlalchemy.schema.Table` object, reflect its columns and properties from the database. If include_columns (a list or set) is specified, limit the autoload to the given column names. The default implementation uses the :class:`~sqlalchemy.engine.reflection.Inspector` interface to provide the output, building upon the granular table/column/ constraint etc. methods of :class:`.Dialect`. """ raise NotImplementedError() def get_columns(self, connection, table_name, schema=None, **kw): """Return information about columns in `table_name`. Given a :class:`.Connection`, a string `table_name`, and an optional string `schema`, return column information as a list of dictionaries with these keys: name the column's name type [sqlalchemy.types#TypeEngine] nullable boolean default the column's default value autoincrement boolean sequence a dictionary of the form {'name' : str, 'start' :int, 'increment': int} Additional column attributes may be present. """ raise NotImplementedError() def get_primary_keys(self, connection, table_name, schema=None, **kw): """Return information about primary keys in `table_name`. Given a :class:`.Connection`, a string `table_name`, and an optional string `schema`, return primary key information as a list of column names. """ raise NotImplementedError() def get_pk_constraint(self, table_name, schema=None, **kw): """Return information about the primary key constraint on table_name`. Given a string `table_name`, and an optional string `schema`, return primary key information as a dictionary with these keys: constrained_columns a list of column names that make up the primary key name optional name of the primary key constraint. """ raise NotImplementedError() def get_foreign_keys(self, connection, table_name, schema=None, **kw): """Return information about foreign_keys in `table_name`. Given a :class:`.Connection`, a string `table_name`, and an optional string `schema`, return foreign key information as a list of dicts with these keys: name the constraint's name constrained_columns a list of column names that make up the foreign key referred_schema the name of the referred schema referred_table the name of the referred table referred_columns a list of column names in the referred table that correspond to constrained_columns """ raise NotImplementedError() def get_table_names(self, connection, schema=None, **kw): """Return a list of table names for `schema`.""" raise NotImplementedError def get_view_names(self, connection, schema=None, **kw): """Return a list of all view names available in the database. schema: Optional, retrieve names from a non-default schema. """ raise NotImplementedError() def get_view_definition(self, connection, view_name, schema=None, **kw): """Return view definition. Given a :class:`.Connection`, a string `view_name`, and an optional string `schema`, return the view definition. """ raise NotImplementedError() def get_indexes(self, connection, table_name, schema=None, **kw): """Return information about indexes in `table_name`. Given a :class:`.Connection`, a string `table_name` and an optional string `schema`, return index information as a list of dictionaries with these keys: name the index's name column_names list of column names in order unique boolean """ raise NotImplementedError() def normalize_name(self, name): """convert the given name to lowercase if it is detected as case insensitive. this method is only used if the dialect defines requires_name_normalize=True. """ raise NotImplementedError() def denormalize_name(self, name): """convert the given name to a case insensitive identifier for the backend if it is an all-lowercase name. this method is only used if the dialect defines requires_name_normalize=True. """ raise NotImplementedError() def has_table(self, connection, table_name, schema=None): """Check the existence of a particular table in the database. Given a :class:`.Connection` object and a string `table_name`, return True if the given table (possibly within the specified `schema`) exists in the database, False otherwise. """ raise NotImplementedError() def has_sequence(self, connection, sequence_name, schema=None): """Check the existence of a particular sequence in the database. Given a :class:`.Connection` object and a string `sequence_name`, return True if the given sequence exists in the database, False otherwise. """ raise NotImplementedError() def _get_server_version_info(self, connection): """Retrieve the server version info from the given connection. This is used by the default implementation to populate the "server_version_info" attribute and is called exactly once upon first connect. """ raise NotImplementedError() def _get_default_schema_name(self, connection): """Return the string name of the currently selected schema from the given connection. This is used by the default implementation to populate the "default_schema_name" attribute and is called exactly once upon first connect. """ raise NotImplementedError() def do_begin(self, connection): """Provide an implementation of *connection.begin()*, given a DB-API connection.""" raise NotImplementedError() def do_rollback(self, connection): """Provide an implementation of *connection.rollback()*, given a DB-API connection.""" raise NotImplementedError() def create_xid(self): """Create a two-phase transaction ID. This id will be passed to do_begin_twophase(), do_rollback_twophase(), do_commit_twophase(). Its format is unspecified. """ raise NotImplementedError() def do_commit(self, connection): """Provide an implementation of *connection.commit()*, given a DB-API connection.""" raise NotImplementedError() def do_savepoint(self, connection, name): """Create a savepoint with the given name on a SQLAlchemy connection.""" raise NotImplementedError() def do_rollback_to_savepoint(self, connection, name): """Rollback a SQL Alchemy connection to the named savepoint.""" raise NotImplementedError() def do_release_savepoint(self, connection, name): """Release the named savepoint on a SQL Alchemy connection.""" raise NotImplementedError() def do_begin_twophase(self, connection, xid): """Begin a two phase transaction on the given connection.""" raise NotImplementedError() def do_prepare_twophase(self, connection, xid): """Prepare a two phase transaction on the given connection.""" raise NotImplementedError() def do_rollback_twophase(self, connection, xid, is_prepared=True, recover=False): """Rollback a two phase transaction on the given connection.""" raise NotImplementedError() def do_commit_twophase(self, connection, xid, is_prepared=True, recover=False): """Commit a two phase transaction on the given connection.""" raise NotImplementedError() def do_recover_twophase(self, connection): """Recover list of uncommited prepared two phase transaction identifiers on the given connection.""" raise NotImplementedError() def do_executemany(self, cursor, statement, parameters, context=None): """Provide an implementation of *cursor.executemany(statement, parameters)*.""" raise NotImplementedError() def do_execute(self, cursor, statement, parameters, context=None): """Provide an implementation of *cursor.execute(statement, parameters)*.""" raise NotImplementedError() def is_disconnect(self, e, connection, cursor): """Return True if the given DB-API error indicates an invalid connection""" raise NotImplementedError() def connect(self): """return a callable which sets up a newly created DBAPI connection. The callable accepts a single argument "conn" which is the DBAPI connection itself. It has no return value. This is used to set dialect-wide per-connection options such as isolation modes, unicode modes, etc. If a callable is returned, it will be assembled into a pool listener that receives the direct DBAPI connection, with all wrappers removed. If None is returned, no listener will be generated. """ return None def reset_isolation_level(self, dbapi_conn): """Given a DBAPI connection, revert its isolation to the default.""" raise NotImplementedError() def set_isolation_level(self, dbapi_conn, level): """Given a DBAPI connection, set its isolation level.""" raise NotImplementedError() def get_isolation_level(self, dbapi_conn): """Given a DBAPI connection, return its isolation level.""" raise NotImplementedError() class ExecutionContext(object): """A messenger object for a Dialect that corresponds to a single execution. ExecutionContext should have these data members: connection Connection object which can be freely used by default value generators to execute SQL. This Connection should reference the same underlying connection/transactional resources of root_connection. root_connection Connection object which is the source of this ExecutionContext. This Connection may have close_with_result=True set, in which case it can only be used once. dialect dialect which created this ExecutionContext. cursor DB-API cursor procured from the connection, compiled if passed to constructor, sqlalchemy.engine.base.Compiled object being executed, statement string version of the statement to be executed. Is either passed to the constructor, or must be created from the sql.Compiled object by the time pre_exec() has completed. parameters bind parameters passed to the execute() method. For compiled statements, this is a dictionary or list of dictionaries. For textual statements, it should be in a format suitable for the dialect's paramstyle (i.e. dict or list of dicts for non positional, list or list of lists/tuples for positional). isinsert True if the statement is an INSERT. isupdate True if the statement is an UPDATE. should_autocommit True if the statement is a "committable" statement. postfetch_cols a list of Column objects for which a server-side default or inline SQL expression value was fired off. Applies to inserts and updates. """ def create_cursor(self): """Return a new cursor generated from this ExecutionContext's connection. Some dialects may wish to change the behavior of connection.cursor(), such as postgresql which may return a PG "server side" cursor. """ raise NotImplementedError() def pre_exec(self): """Called before an execution of a compiled statement. If a compiled statement was passed to this ExecutionContext, the `statement` and `parameters` datamembers must be initialized after this statement is complete. """ raise NotImplementedError() def post_exec(self): """Called after the execution of a compiled statement. If a compiled statement was passed to this ExecutionContext, the `last_insert_ids`, `last_inserted_params`, etc. datamembers should be available after this method completes. """ raise NotImplementedError() def result(self): """Return a result object corresponding to this ExecutionContext. Returns a ResultProxy. """ raise NotImplementedError() def handle_dbapi_exception(self, e): """Receive a DBAPI exception which occurred upon execute, result fetch, etc.""" raise NotImplementedError() def should_autocommit_text(self, statement): """Parse the given textual statement and return True if it refers to a "committable" statement""" raise NotImplementedError() def lastrow_has_defaults(self): """Return True if the last INSERT or UPDATE row contained inlined or database-side defaults. """ raise NotImplementedError() def get_rowcount(self): """Return the number of rows produced (by a SELECT query) or affected (by an INSERT/UPDATE/DELETE statement). Note that this row count may not be properly implemented in some dialects; this is indicated by the ``supports_sane_rowcount`` and ``supports_sane_multi_rowcount`` dialect attributes. """ raise NotImplementedError() class Compiled(object): """Represent a compiled SQL or DDL expression. The ``__str__`` method of the ``Compiled`` object should produce the actual text of the statement. ``Compiled`` objects are specific to their underlying database dialect, and also may or may not be specific to the columns referenced within a particular set of bind parameters. In no case should the ``Compiled`` object be dependent on the actual values of those bind parameters, even though it may reference those values as defaults. """ def __init__(self, dialect, statement, bind=None): """Construct a new ``Compiled`` object. :param dialect: ``Dialect`` to compile against. :param statement: ``ClauseElement`` to be compiled. :param bind: Optional Engine or Connection to compile this statement against. """ self.dialect = dialect self.bind = bind if statement is not None: self.statement = statement self.can_execute = statement.supports_execution self.string = self.process(self.statement) @util.deprecated("0.7", ":class:`.Compiled` objects now compile " "within the constructor.") def compile(self): """Produce the internal string representation of this element.""" pass @property def sql_compiler(self): """Return a Compiled that is capable of processing SQL expressions. If this compiler is one, it would likely just return 'self'. """ raise NotImplementedError() def process(self, obj, **kwargs): return obj._compiler_dispatch(self, **kwargs) def __str__(self): """Return the string text of the generated SQL or DDL.""" return self.string or '' def construct_params(self, params=None): """Return the bind params for this compiled object. :param params: a dict of string/object pairs whos values will override bind values compiled in to the statement. """ raise NotImplementedError() @property def params(self): """Return the bind params for this compiled object.""" return self.construct_params() def execute(self, *multiparams, **params): """Execute this compiled object.""" e = self.bind if e is None: raise exc.UnboundExecutionError( "This Compiled object is not bound to any Engine " "or Connection.") return e._execute_compiled(self, multiparams, params) def scalar(self, *multiparams, **params): """Execute this compiled object and return the result's scalar value.""" return self.execute(*multiparams, **params).scalar() class TypeCompiler(object): """Produces DDL specification for TypeEngine objects.""" def __init__(self, dialect): self.dialect = dialect def process(self, type_): return type_._compiler_dispatch(self) class Connectable(object): """Interface for an object which supports execution of SQL constructs. The two implementations of :class:`.Connectable` are :class:`.Connection` and :class:`.Engine`. Connectable must also implement the 'dialect' member which references a :class:`.Dialect` instance. """ def connect(self, **kwargs): """Return a :class:`.Connection` object. Depending on context, this may be ``self`` if this object is already an instance of :class:`.Connection`, or a newly procured :class:`.Connection` if this object is an instance of :class:`.Engine`. """ def contextual_connect(self): """Return a :class:`.Connection` object which may be part of an ongoing context. Depending on context, this may be ``self`` if this object is already an instance of :class:`.Connection`, or a newly procured :class:`.Connection` if this object is an instance of :class:`.Engine`. """ raise NotImplementedError() @util.deprecated("0.7", "Use the create() method on the given schema " "object directly, i.e. :meth:`.Table.create`, " ":meth:`.Index.create`, :meth:`.MetaData.create_all`") def create(self, entity, **kwargs): """Emit CREATE statements for the given schema entity.""" raise NotImplementedError() @util.deprecated("0.7", "Use the drop() method on the given schema " "object directly, i.e. :meth:`.Table.drop`, " ":meth:`.Index.drop`, :meth:`.MetaData.drop_all`") def drop(self, entity, **kwargs): """Emit DROP statements for the given schema entity.""" raise NotImplementedError() def execute(self, object, *multiparams, **params): """Executes the given construct and returns a :class:`.ResultProxy`.""" raise NotImplementedError() def scalar(self, object, *multiparams, **params): """Executes and returns the first column of the first row. The underlying cursor is closed after execution. """ raise NotImplementedError() def _run_visitor(self, visitorcallable, element, **kwargs): raise NotImplementedError() def _execute_clauseelement(self, elem, multiparams=None, params=None): raise NotImplementedError() class Connection(Connectable): """Provides high-level functionality for a wrapped DB-API connection. Provides execution support for string-based SQL statements as well as :class:`.ClauseElement`, :class:`.Compiled` and :class:`.DefaultGenerator` objects. Provides a :meth:`begin` method to return :class:`.Transaction` objects. 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 """ def __init__(self, engine, connection=None, close_with_result=False, _branch=False, _execution_options=None): """Construct a new Connection. The constructor here is not public and is only called only by an :class:`.Engine`. See :meth:`.Engine.connect` and :meth:`.Engine.contextual_connect` methods. """ self.engine = engine self.dialect = engine.dialect self.__connection = connection or engine.raw_connection() self.__transaction = None self.should_close_with_result = close_with_result self.__savepoint_seq = 0 self.__branch = _branch self.__invalid = False self._has_events = engine._has_events self._echo = self.engine._should_log_info() if _execution_options: self._execution_options =\ engine._execution_options.union(_execution_options) else: self._execution_options = engine._execution_options def _branch(self): """Return a new Connection which references this Connection's engine and connection; but does not have close_with_result enabled, and also whose close() method does nothing. This is used to execute "sub" statements within a single execution, usually an INSERT statement. """ return self.engine._connection_cls( self.engine, self.__connection, _branch=True) def _clone(self): """Create a shallow copy of this Connection. """ c = self.__class__.__new__(self.__class__) c.__dict__ = self.__dict__.copy() return c def execution_options(self, **opt): """ Set non-SQL options for the connection which take effect during execution. The method returns a copy of this :class:`.Connection` which references the same underlying DBAPI connection, but also defines the given execution options which will take effect for a call to :meth:`execute`. As the new :class:`.Connection` references the same underlying resource, it is probably best to ensure that the copies would be discarded immediately, which is implicit if used as in:: result = connection.execution_options(stream_results=True).\\ execute(stmt) :meth:`.Connection.execution_options` accepts all options as those accepted by :meth:`.Executable.execution_options`. Additionally, it includes options that are applicable only to :class:`.Connection`. :param autocommit: Available on: Connection, statement. When True, a COMMIT will be invoked after execution when executed in 'autocommit' mode, i.e. when an explicit transaction is not begun on the connection. Note that DBAPI connections by default are always in a transaction - SQLAlchemy uses rules applied to different kinds of statements to determine if COMMIT will be invoked in order to provide its "autocommit" feature. Typically, all INSERT/UPDATE/DELETE statements as well as CREATE/DROP statements have autocommit behavior enabled; SELECT constructs do not. Use this option when invoking a SELECT or other specific SQL construct where COMMIT is desired (typically when calling stored procedures and such), and an explicit transaction is not in progress. :param compiled_cache: Available on: Connection. A dictionary where :class:`.Compiled` objects will be cached when the :class:`.Connection` compiles a clause expression into a :class:`.Compiled` object. It is the user's responsibility to manage the size of this dictionary, which will have keys corresponding to the dialect, clause element, the column names within the VALUES or SET clause of an INSERT or UPDATE, as well as the "batch" mode for an INSERT or UPDATE statement. The format of this dictionary is not guaranteed to stay the same in future releases. 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 isolation_level: Available on: Connection. Set the transaction isolation level for the lifespan of this connection. Valid values include those string values accepted by the ``isolation_level`` parameter passed to :func:`.create_engine`, and are database specific, including those for :ref:`sqlite_toplevel`, :ref:`postgresql_toplevel` - see those dialect's documentation for further info. Note that this option necessarily affects the underying DBAPI connection for the lifespan of the originating :class:`.Connection`, and is not per-execution. This setting is not removed until the underying DBAPI connection is returned to the connection pool, i.e. the :meth:`.Connection.close` method is called. :param stream_results: Available on: Connection, statement. Indicate to the dialect that results should be "streamed" and not pre-buffered, if possible. This is a limitation of many DBAPIs. The flag is currently understood only by the psycopg2 dialect. """ c = self._clone() c._execution_options = c._execution_options.union(opt) if 'isolation_level' in opt: c._set_isolation_level() return c def _set_isolation_level(self): self.dialect.set_isolation_level(self.connection, self._execution_options['isolation_level']) self.connection._connection_record.finalize_callback = \ self.dialect.reset_isolation_level @property def closed(self): """Return True if this connection is closed.""" return not self.__invalid and '_Connection__connection' \ not in self.__dict__ @property def invalidated(self): """Return True if this connection was invalidated.""" return self.__invalid @property def connection(self): "The underlying DB-API connection managed by this Connection." try: return self.__connection except AttributeError: return self._revalidate_connection() def _revalidate_connection(self): if self.__invalid: if self.__transaction is not None: raise exc.InvalidRequestError( "Can't reconnect until invalid " "transaction is rolled back") self.__connection = self.engine.raw_connection() self.__invalid = False return self.__connection raise exc.ResourceClosedError("This Connection is closed") @property def _connection_is_valid(self): # use getattr() for is_valid to support exceptions raised in # dialect initializer, where the connection is not wrapped in # _ConnectionFairy return getattr(self.__connection, 'is_valid', False) @property def _still_open_and_connection_is_valid(self): return \ not self.closed and \ not self.invalidated and \ getattr(self.__connection, 'is_valid', False) @property def info(self): """A collection of per-DB-API connection instance properties.""" return self.connection.info def connect(self): """Returns self. This ``Connectable`` interface method returns self, allowing Connections to be used interchangably with Engines in most situations that require a bind. """ return self def contextual_connect(self, **kwargs): """Returns self. This ``Connectable`` interface method returns self, allowing Connections to be used interchangably with Engines in most situations that require a bind. """ return self def invalidate(self, exception=None): """Invalidate the underlying DBAPI connection associated with this Connection. The underlying DB-API connection is literally closed (if possible), and is discarded. Its source connection pool will typically lazily create a new connection to replace it. Upon the next usage, this Connection will attempt to reconnect to the pool with a new connection. Transactions in progress remain in an "opened" state (even though the actual transaction is gone); these must be explicitly rolled back before a reconnect on this Connection can proceed. This is to prevent applications from accidentally continuing their transactional operations in a non-transactional state. """ if self.invalidated: return if self.closed: raise exc.ResourceClosedError("This Connection is closed") if self._connection_is_valid: self.__connection.invalidate(exception) del self.__connection self.__invalid = True def detach(self): """Detach the underlying DB-API connection from its connection pool. This Connection instance will remain useable. When closed, the DB-API connection will be literally closed and not returned to its pool. The pool will typically lazily create a new connection to replace the detached connection. 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). Also see :class:`~sqlalchemy.interfaces.PoolListener` for a mechanism to modify connection state when connections leave and return to their connection pool. """ self.__connection.detach() def begin(self): """Begin a transaction and return a transaction handle. The returned object is an instance of :class:`.Transaction`. Repeated calls to ``begin`` on the same Connection will create a lightweight, emulated nested transaction. Only the outermost transaction may ``commit``. Calls to ``commit`` on inner transactions are ignored. Any transaction in the hierarchy may ``rollback``, however. See also :meth:`.Connection.begin_nested`, :meth:`.Connection.begin_twophase`. """ if self.__transaction is None: self.__transaction = RootTransaction(self) return self.__transaction else: return Transaction(self, self.__transaction) def begin_nested(self): """Begin a nested transaction and return a transaction handle. The returned object is an instance of :class:`.NestedTransaction`. Nested transactions require SAVEPOINT support in the underlying database. Any transaction in the hierarchy may ``commit`` and ``rollback``, however the outermost transaction still controls the overall ``commit`` or ``rollback`` of the transaction of a whole. See also :meth:`.Connection.begin`, :meth:`.Connection.begin_twophase`. """ if self.__transaction is None: self.__transaction = RootTransaction(self) else: self.__transaction = NestedTransaction(self, self.__transaction) return self.__transaction def begin_twophase(self, xid=None): """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. See also :meth:`.Connection.begin`, :meth:`.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(); self.__transaction = TwoPhaseTransaction(self, xid) return self.__transaction def recover_twophase(self): return self.engine.dialect.do_recover_twophase(self) def rollback_prepared(self, xid, recover=False): self.engine.dialect.do_rollback_twophase(self, xid, recover=recover) def commit_prepared(self, xid, recover=False): self.engine.dialect.do_commit_twophase(self, xid, recover=recover) def in_transaction(self): """Return True if a transaction is in progress.""" return self.__transaction is not None def _begin_impl(self): if self._echo: self.engine.logger.info("BEGIN (implicit)") if self._has_events: self.engine.dispatch.begin(self) try: self.engine.dialect.do_begin(self.connection) except Exception, e: self._handle_dbapi_exception(e, None, None, None, None) raise def _rollback_impl(self): if self._has_events: self.engine.dispatch.rollback(self) if self._still_open_and_connection_is_valid: if self._echo: self.engine.logger.info("ROLLBACK") try: self.engine.dialect.do_rollback(self.connection) self.__transaction = None except Exception, e: self._handle_dbapi_exception(e, None, None, None, None) raise else: self.__transaction = None def _commit_impl(self): if self._has_events: self.engine.dispatch.commit(self) if self._echo: self.engine.logger.info("COMMIT") try: self.engine.dialect.do_commit(self.connection) self.__transaction = None except Exception, e: self._handle_dbapi_exception(e, None, None, None, None) raise def _savepoint_impl(self, name=None): if self._has_events: self.engine.dispatch.savepoint(self, name) if name is None: self.__savepoint_seq += 1 name = 'sa_savepoint_%s' % self.__savepoint_seq if self._still_open_and_connection_is_valid: self.engine.dialect.do_savepoint(self, name) return name def _rollback_to_savepoint_impl(self, name, context): if self._has_events: self.engine.dispatch.rollback_savepoint(self, name, context) if self._still_open_and_connection_is_valid: self.engine.dialect.do_rollback_to_savepoint(self, name) self.__transaction = context def _release_savepoint_impl(self, name, context): if self._has_events: self.engine.dispatch.release_savepoint(self, name, context) if self._still_open_and_connection_is_valid: self.engine.dialect.do_release_savepoint(self, name) self.__transaction = context def _begin_twophase_impl(self, xid): if self._has_events: self.engine.dispatch.begin_twophase(self, xid) if self._still_open_and_connection_is_valid: self.engine.dialect.do_begin_twophase(self, xid) def _prepare_twophase_impl(self, xid): if self._has_events: self.engine.dispatch.prepare_twophase(self, xid) if self._still_open_and_connection_is_valid: assert isinstance(self.__transaction, TwoPhaseTransaction) self.engine.dialect.do_prepare_twophase(self, xid) def _rollback_twophase_impl(self, xid, is_prepared): if self._has_events: self.engine.dispatch.rollback_twophase(self, xid, is_prepared) if self._still_open_and_connection_is_valid: assert isinstance(self.__transaction, TwoPhaseTransaction) self.engine.dialect.do_rollback_twophase(self, xid, is_prepared) self.__transaction = None def _commit_twophase_impl(self, xid, is_prepared): if self._has_events: self.engine.dispatch.commit_twophase(self, xid, is_prepared) if self._still_open_and_connection_is_valid: assert isinstance(self.__transaction, TwoPhaseTransaction) self.engine.dialect.do_commit_twophase(self, xid, is_prepared) self.__transaction = None def _autorollback(self): if not self.in_transaction(): self._rollback_impl() def close(self): """Close this :class:`.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` referenced by the :class:`.Engine` that produced this :class:`.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:`.Connection`. After :meth:`~.Connection.close` is called, the :class:`.Connection` is permanently in a closed state, and will allow no further operations. """ try: conn = self.__connection except AttributeError: return if not self.__branch: conn.close() self.__invalid = False del self.__connection self.__transaction = None def scalar(self, object, *multiparams, **params): """Executes and returns the first column of the first row. The underlying result/cursor is closed after execution. """ return self.execute(object, *multiparams, **params).scalar() def execute(self, object, *multiparams, **params): """Executes the a SQL statement construct and returns a :class:`.ResultProxy`. :param object: The statement to be executed. May be one of: * a plain string * any :class:`.ClauseElement` construct that is also a subclass of :class:`.Executable`, such as a :func:`~.expression.select` construct * a :class:`.FunctionElement`, such as that generated by :attr:`.func`, will be automatically wrapped in a SELECT statement, which is then executed. * a :class:`.DDLElement` object * a :class:`.DefaultGenerator` object * a :class:`.Compiled` object :param \*multiparams/\**params: represent bound parameter values to be used in the execution. Typically, the format is either a collection of one or more dictionaries passed to \*multiparams:: conn.execute( table.insert(), {"id":1, "value":"v1"}, {"id":2, "value":"v2"} ) ...or individual key/values interpreted by \**params:: conn.execute( table.insert(), id=1, value="v1" ) In the case that a plain SQL string is passed, and the underlying DBAPI accepts positional bind parameters, a collection of tuples or individual values in \*multiparams may be passed:: conn.execute( "INSERT INTO table (id, value) VALUES (?, ?)", (1, "v1"), (2, "v2") ) conn.execute( "INSERT INTO table (id, value) VALUES (?, ?)", 1, "v1" ) Note above, the usage of a question mark "?" or other symbol is contingent upon the "paramstyle" accepted by the DBAPI in use, which may be any of "qmark", "named", "pyformat", "format", "numeric". See `pep-249 `_ for details on paramstyle. To execute a textual SQL statement which uses bound parameters in a DBAPI-agnostic way, use the :func:`~.expression.text` construct. """ for c in type(object).__mro__: if c in Connection.executors: return Connection.executors[c]( self, object, multiparams, params) else: raise exc.InvalidRequestError( "Unexecutable object type: %s" % type(object)) def __distill_params(self, multiparams, params): """Given arguments from the calling form *multiparams, **params, return a list of bind parameter structures, usually a list of dictionaries. In the case of 'raw' execution which accepts positional parameters, it may be a list of tuples or lists. """ if not multiparams: if params: return [params] else: return [] elif len(multiparams) == 1: zero = multiparams[0] if isinstance(zero, (list, tuple)): if not zero or hasattr(zero[0], '__iter__'): return zero else: return [zero] elif hasattr(zero, 'keys'): return [zero] else: return [[zero]] else: if hasattr(multiparams[0], '__iter__'): return multiparams else: return [multiparams] def _execute_function(self, func, multiparams, params): """Execute a sql.FunctionElement object.""" return self._execute_clauseelement(func.select(), multiparams, params) def _execute_default(self, default, multiparams, params): """Execute a schema.ColumnDefault object.""" if self._has_events: for fn in self.engine.dispatch.before_execute: default, multiparams, params = \ fn(self, default, multiparams, params) try: try: conn = self.__connection except AttributeError: conn = self._revalidate_connection() dialect = self.dialect ctx = dialect.execution_ctx_cls._init_default( dialect, self, conn) except Exception, e: self._handle_dbapi_exception(e, None, None, None, None) raise ret = ctx._exec_default(default, None) if self.should_close_with_result: self.close() if self._has_events: self.engine.dispatch.after_execute(self, default, multiparams, params, ret) return ret def _execute_ddl(self, ddl, multiparams, params): """Execute a schema.DDL object.""" if self._has_events: for fn in self.engine.dispatch.before_execute: ddl, multiparams, params = \ fn(self, ddl, multiparams, params) dialect = self.dialect compiled = ddl.compile(dialect=dialect) ret = self._execute_context( dialect, dialect.execution_ctx_cls._init_ddl, compiled, None, compiled ) if self._has_events: self.engine.dispatch.after_execute(self, ddl, multiparams, params, ret) return ret def _execute_clauseelement(self, elem, multiparams, params): """Execute a sql.ClauseElement object.""" if self._has_events: for fn in self.engine.dispatch.before_execute: elem, multiparams, params = \ fn(self, elem, multiparams, params) distilled_params = self.__distill_params(multiparams, params) if distilled_params: keys = distilled_params[0].keys() else: keys = [] dialect = self.dialect if 'compiled_cache' in self._execution_options: key = dialect, elem, tuple(keys), len(distilled_params) > 1 if key in self._execution_options['compiled_cache']: compiled_sql = self._execution_options['compiled_cache'][key] else: compiled_sql = elem.compile( dialect=dialect, column_keys=keys, inline=len(distilled_params) > 1) self._execution_options['compiled_cache'][key] = compiled_sql else: compiled_sql = elem.compile( dialect=dialect, column_keys=keys, inline=len(distilled_params) > 1) ret = self._execute_context( dialect, dialect.execution_ctx_cls._init_compiled, compiled_sql, distilled_params, compiled_sql, distilled_params ) if self._has_events: self.engine.dispatch.after_execute(self, elem, multiparams, params, ret) return ret def _execute_compiled(self, compiled, multiparams, params): """Execute a sql.Compiled object.""" if self._has_events: for fn in self.engine.dispatch.before_execute: compiled, multiparams, params = \ fn(self, compiled, multiparams, params) dialect = self.dialect parameters=self.__distill_params(multiparams, params) ret = self._execute_context( dialect, dialect.execution_ctx_cls._init_compiled, compiled, parameters, compiled, parameters ) if self._has_events: self.engine.dispatch.after_execute(self, compiled, multiparams, params, ret) return ret def _execute_text(self, statement, multiparams, params): """Execute a string SQL statement.""" if self._has_events: for fn in self.engine.dispatch.before_execute: statement, multiparams, params = \ fn(self, statement, multiparams, params) dialect = self.dialect parameters = self.__distill_params(multiparams, params) ret = self._execute_context( dialect, dialect.execution_ctx_cls._init_statement, statement, parameters, statement, parameters ) if self._has_events: self.engine.dispatch.after_execute(self, statement, multiparams, params, ret) return ret def _execute_context(self, dialect, constructor, statement, parameters, *args): """Create an :class:`.ExecutionContext` and execute, returning a :class:`.ResultProxy`.""" try: try: conn = self.__connection except AttributeError: conn = self._revalidate_connection() context = constructor(dialect, self, conn, *args) except Exception, e: self._handle_dbapi_exception(e, str(statement), parameters, None, None) raise if context.compiled: context.pre_exec() cursor, statement, parameters = context.cursor, \ context.statement, \ context.parameters if not context.executemany: parameters = parameters[0] if self._has_events: for fn in self.engine.dispatch.before_cursor_execute: statement, parameters = \ fn(self, cursor, statement, parameters, context, context.executemany) if self._echo: self.engine.logger.info(statement) self.engine.logger.info("%r", sql_util._repr_params(parameters, batches=10)) try: if context.executemany: self.dialect.do_executemany( cursor, statement, parameters, context) else: self.dialect.do_execute( cursor, statement, parameters, context) except Exception, e: self._handle_dbapi_exception( e, statement, parameters, cursor, context) raise if self._has_events: self.engine.dispatch.after_cursor_execute(self, cursor, statement, parameters, context, context.executemany) if context.compiled: context.post_exec() if context.isinsert and not context.executemany: context.post_insert() # create a resultproxy, get rowcount/implicit RETURNING # rows, close cursor if no further results pending result = context.get_result_proxy() if context.isinsert: if context._is_implicit_returning: context._fetch_implicit_returning(result) result.close(_autoclose_connection=False) elif not context._is_explicit_returning: result.close(_autoclose_connection=False) elif result._metadata is None: # no results, get rowcount # (which requires open cursor on some drivers # such as kintersbasdb, mxodbc), result.rowcount result.close(_autoclose_connection=False) if self.__transaction is None and context.should_autocommit: self._commit_impl() if result.closed and self.should_close_with_result: self.close() return result def _cursor_execute(self, cursor, statement, parameters): """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._echo: self.engine.logger.info(statement) self.engine.logger.info("%r", parameters) try: self.dialect.do_execute( cursor, statement, parameters) except Exception, e: self._handle_dbapi_exception( e, statement, parameters, cursor, None) raise def _safe_close_cursor(self, cursor): """Close the given cursor, catching exceptions and turning into log warnings. """ try: cursor.close() except Exception, e: try: ex_text = str(e) except TypeError: ex_text = repr(e) self.connection._logger.warn("Error closing cursor: %s", ex_text) if isinstance(e, (SystemExit, KeyboardInterrupt)): raise def _handle_dbapi_exception(self, e, statement, parameters, cursor, context): if getattr(self, '_reentrant_error', False): # Py3K #raise exc.DBAPIError.instance(statement, parameters, e, # self.dialect.dbapi.Error) from e # Py2K raise exc.DBAPIError.instance(statement, parameters, e, self.dialect.dbapi.Error), \ None, sys.exc_info()[2] # end Py2K self._reentrant_error = True try: # non-DBAPI error - if we already got a context, # or theres no string statement, don't wrap it should_wrap = isinstance(e, self.dialect.dbapi.Error) or \ (statement is not None and context is None) if should_wrap and context: context.handle_dbapi_exception(e) is_disconnect = isinstance(e, self.dialect.dbapi.Error) and \ self.dialect.is_disconnect(e, self.__connection, cursor) if is_disconnect: self.invalidate(e) self.engine.dispose() else: if cursor: self._safe_close_cursor(cursor) self._autorollback() if self.should_close_with_result: self.close() if not should_wrap: return # Py3K #raise exc.DBAPIError.instance( # statement, # parameters, # e, # self.dialect.dbapi.Error, # connection_invalidated=is_disconnect) \ # from e # Py2K raise exc.DBAPIError.instance( statement, parameters, e, self.dialect.dbapi.Error, connection_invalidated=is_disconnect), \ None, sys.exc_info()[2] # end Py2K finally: del self._reentrant_error # poor man's multimethod/generic function thingy executors = { expression.FunctionElement: _execute_function, expression.ClauseElement: _execute_clauseelement, Compiled: _execute_compiled, schema.SchemaItem: _execute_default, schema.DDLElement: _execute_ddl, basestring: _execute_text } @util.deprecated("0.7", "Use the create() method on the given schema " "object directly, i.e. :meth:`.Table.create`, " ":meth:`.Index.create`, :meth:`.MetaData.create_all`") def create(self, entity, **kwargs): """Emit CREATE statements for the given schema entity.""" return self.engine.create(entity, connection=self, **kwargs) @util.deprecated("0.7", "Use the drop() method on the given schema " "object directly, i.e. :meth:`.Table.drop`, " ":meth:`.Index.drop`, :meth:`.MetaData.drop_all`") def drop(self, entity, **kwargs): """Emit DROP statements for the given schema entity.""" return self.engine.drop(entity, connection=self, **kwargs) @util.deprecated("0.7", "Use autoload=True with :class:`.Table`, " "or use the :class:`.Inspector` object.") def reflecttable(self, table, include_columns=None): """Load table description from the database. Given a :class:`.Table` object, reflect its columns and properties from the database, populating the given :class:`.Table` object with attributes.. If include_columns (a list or set) is specified, limit the autoload to the given column names. The default implementation uses the :class:`.Inspector` interface to provide the output, building upon the granular table/column/ constraint etc. methods of :class:`.Dialect`. """ return self.engine.reflecttable(table, self, include_columns) def default_schema_name(self): return self.engine.dialect.get_default_schema_name(self) def transaction(self, callable_, *args, **kwargs): """Execute the given function within a transaction boundary. The function is passed this :class:`.Connection` as the first argument, followed by the given \*args and \**kwargs. This is a shortcut for explicitly invoking :meth:`.Connection.begin`, calling :meth:`.Transaction.commit` upon success or :meth:`.Transaction.rollback` upon an exception raise:: def do_something(conn, x, y): conn.execute("some statement", {'x':x, 'y':y}) conn.transaction(do_something, 5, 10) Note that context managers (i.e. the ``with`` statement) present a more modern way of accomplishing the above, using the :class:`.Transaction` object as a base:: with conn.begin(): conn.execute("some statement", {'x':5, 'y':10}) One advantage to the :meth:`.Connection.transaction` method is that the same method is also available on :class:`.Engine` as :meth:`.Engine.transaction` - this method procures a :class:`.Connection` and then performs the same operation, allowing equivalent usage with either a :class:`.Connection` or :class:`.Engine` without needing to know what kind of object it is. """ trans = self.begin() try: ret = self.run_callable(callable_, *args, **kwargs) trans.commit() return ret except: trans.rollback() raise def run_callable(self, callable_, *args, **kwargs): """Given a callable object or function, execute it, passing a :class:`.Connection` as the first argument. The given \*args and \**kwargs are passed subsequent to the :class:`.Connection` argument. This function, along with :meth:`.Engine.run_callable`, allows a function to be run with a :class:`.Connection` or :class:`.Engine` object without the need to know which one is being dealt with. """ return callable_(self, *args, **kwargs) def _run_visitor(self, visitorcallable, element, **kwargs): visitorcallable(self.dialect, self, **kwargs).traverse_single(element) class Transaction(object): """Represent a database transaction in progress. The :class:`.Transaction` object is procured by calling the :meth:`~.Connection.begin` method of :class:`.Connection`:: from sqlalchemy import create_engine engine = create_engine("postgresql://scott:tiger@localhost/test") connection = engine.connect() trans = connection.begin() connection.execute("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:`.Connection.begin` method:: with connection.begin(): connection.execute("insert into x (a, b) values (1, 2)") The Transaction object is **not** threadsafe. See also: :meth:`.Connection.begin`, :meth:`.Connection.begin_twophase`, :meth:`.Connection.begin_nested`. .. index:: single: thread safety; Transaction """ def __init__(self, connection, parent): self.connection = connection self._parent = parent or self self.is_active = True def close(self): """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. """ if not self._parent.is_active: return if self._parent is self: self.rollback() def rollback(self): """Roll back this :class:`.Transaction`. """ if not self._parent.is_active: return self._do_rollback() self.is_active = False def _do_rollback(self): self._parent.rollback() def commit(self): """Commit this :class:`.Transaction`.""" if not self._parent.is_active: raise exc.InvalidRequestError("This transaction is inactive") self._do_commit() self.is_active = False def _do_commit(self): pass def __enter__(self): return self def __exit__(self, type, value, traceback): if type is None and self.is_active: try: self.commit() except: self.rollback() raise else: self.rollback() class RootTransaction(Transaction): def __init__(self, connection): super(RootTransaction, self).__init__(connection, None) self.connection._begin_impl() def _do_rollback(self): if self.is_active: self.connection._rollback_impl() def _do_commit(self): if self.is_active: self.connection._commit_impl() class NestedTransaction(Transaction): """Represent a 'nested', or SAVEPOINT transaction. A new :class:`.NestedTransaction` object may be procured using the :meth:`.Connection.begin_nested` method. The interface is the same as that of :class:`.Transaction`. """ def __init__(self, connection, parent): super(NestedTransaction, self).__init__(connection, parent) self._savepoint = self.connection._savepoint_impl() def _do_rollback(self): if self.is_active: self.connection._rollback_to_savepoint_impl( self._savepoint, self._parent) def _do_commit(self): if self.is_active: self.connection._release_savepoint_impl( self._savepoint, self._parent) class TwoPhaseTransaction(Transaction): """Represent a two-phase transaction. A new :class:`.TwoPhaseTransaction` object may be procured using the :meth:`.Connection.begin_twophase` method. The interface is the same as that of :class:`.Transaction` with the addition of the :meth:`prepare` method. """ def __init__(self, connection, xid): super(TwoPhaseTransaction, self).__init__(connection, None) self._is_prepared = False self.xid = xid self.connection._begin_twophase_impl(self.xid) def prepare(self): """Prepare this :class:`.TwoPhaseTransaction`. After a PREPARE, the transaction can be committed. """ if not self._parent.is_active: raise exc.InvalidRequestError("This transaction is inactive") self.connection._prepare_twophase_impl(self.xid) self._is_prepared = True def _do_rollback(self): self.connection._rollback_twophase_impl(self.xid, self._is_prepared) def _do_commit(self): self.connection._commit_twophase_impl(self.xid, self._is_prepared) class Engine(Connectable, log.Identified): """ Connects a :class:`~sqlalchemy.pool.Pool` and :class:`~sqlalchemy.engine.base.Dialect` together to provide a source of database connectivity and behavior. An :class:`.Engine` object is instantiated publically using the :func:`~sqlalchemy.create_engine` function. See also: :ref:`engines_toplevel` :ref:`connections_toplevel` """ _execution_options = util.immutabledict() _has_events = False _connection_cls = Connection def __init__(self, pool, dialect, url, logging_name=None, echo=None, proxy=None, execution_options=None ): self.pool = pool self.url = url self.dialect = dialect if logging_name: self.logging_name = logging_name self.echo = echo self.engine = self log.instance_logger(self, echoflag=echo) if proxy: interfaces.ConnectionProxy._adapt_listener(self, proxy) if execution_options: if 'isolation_level' in execution_options: raise exc.ArgumentError( "'isolation_level' execution option may " "only be specified on Connection.execution_options(). " "To set engine-wide isolation level, " "use the isolation_level argument to create_engine()." ) self.update_execution_options(**execution_options) dispatch = event.dispatcher(events.ConnectionEvents) def update_execution_options(self, **opt): """Update the default execution_options dictionary of this :class:`.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`` paramter to :func:`.create_engine`. See :meth:`.Connection.execution_options` for more details on execution options. """ self._execution_options = \ self._execution_options.union(opt) @property def name(self): """String name of the :class:`~sqlalchemy.engine.Dialect` in use by this ``Engine``.""" return self.dialect.name @property def driver(self): """Driver name of the :class:`~sqlalchemy.engine.Dialect` in use by this ``Engine``.""" return self.dialect.driver echo = log.echo_property() def __repr__(self): return 'Engine(%s)' % str(self.url) def dispose(self): """Dispose of the connection pool used by this :class:`.Engine`. A new connection pool is created immediately after the old one has been disposed. This new pool, like all SQLAlchemy connection pools, does not make any actual connections to the database until one is first requested. This method has two general use cases: * When a dropped connection is detected, it is assumed that all connections held by the pool are potentially dropped, and the entire pool is replaced. * An application may want to use :meth:`dispose` within a test suite that is creating multiple engines. It is critical to note that :meth:`dispose` does **not** guarantee that the application will release all open database connections - only those connections that are checked into the pool are closed. Connections which remain checked out or have been detached from the engine are not affected. """ self.pool.dispose() self.pool = self.pool.recreate() @util.deprecated("0.7", "Use the create() method on the given schema " "object directly, i.e. :meth:`.Table.create`, " ":meth:`.Index.create`, :meth:`.MetaData.create_all`") def create(self, entity, connection=None, **kwargs): """Emit CREATE statements for the given schema entity.""" from sqlalchemy.engine import ddl self._run_visitor(ddl.SchemaGenerator, entity, connection=connection, **kwargs) @util.deprecated("0.7", "Use the drop() method on the given schema " "object directly, i.e. :meth:`.Table.drop`, " ":meth:`.Index.drop`, :meth:`.MetaData.drop_all`") def drop(self, entity, connection=None, **kwargs): """Emit DROP statements for the given schema entity.""" from sqlalchemy.engine import ddl self._run_visitor(ddl.SchemaDropper, entity, connection=connection, **kwargs) def _execute_default(self, default): connection = self.contextual_connect() try: return connection._execute_default(default, (), {}) finally: connection.close() @property @util.deprecated("0.7", "Use :attr:`~sqlalchemy.sql.expression.func` to create function constructs.") def func(self): return expression._FunctionGenerator(bind=self) @util.deprecated("0.7", "Use :func:`.expression.text` to create text constructs.") def text(self, text, *args, **kwargs): """Return a :func:`~sqlalchemy.sql.expression.text` construct, bound to this engine. This is equivalent to:: text("SELECT * FROM table", bind=engine) """ return expression.text(text, bind=self, *args, **kwargs) def _run_visitor(self, visitorcallable, element, connection=None, **kwargs): if connection is None: conn = self.contextual_connect(close_with_result=False) else: conn = connection try: conn._run_visitor(visitorcallable, element, **kwargs) finally: if connection is None: conn.close() def transaction(self, callable_, *args, **kwargs): """Execute the given function within a transaction boundary. The function is passed a newly procured :class:`.Connection` as the first argument, followed by the given \*args and \**kwargs. The :class:`.Connection` is then closed (returned to the pool) when the operation is complete. This method can be used interchangeably with :meth:`.Connection.transaction`. See that method for more details on usage as well as a modern alternative using context managers (i.e. the ``with`` statement). """ conn = self.contextual_connect() try: return conn.transaction(callable_, *args, **kwargs) finally: conn.close() def run_callable(self, callable_, *args, **kwargs): """Given a callable object or function, execute it, passing a :class:`.Connection` as the first argument. The given \*args and \**kwargs are passed subsequent to the :class:`.Connection` argument. This function, along with :meth:`.Connection.run_callable`, allows a function to be run with a :class:`.Connection` or :class:`.Engine` object without the need to know which one is being dealt with. """ conn = self.contextual_connect() try: return conn.run_callable(callable_, *args, **kwargs) finally: conn.close() def execute(self, statement, *multiparams, **params): """Executes the given construct and returns a :class:`.ResultProxy`. The arguments are the same as those used by :meth:`.Connection.execute`. Here, a :class:`.Connection` is acquired using the :meth:`~.Engine.contextual_connect` method, and the statement executed with that connection. The returned :class:`.ResultProxy` is flagged such that when the :class:`.ResultProxy` is exhausted and its underlying cursor is closed, the :class:`.Connection` created here will also be closed, which allows its associated DBAPI connection resource to be returned to the connection pool. """ connection = self.contextual_connect(close_with_result=True) return connection.execute(statement, *multiparams, **params) def scalar(self, statement, *multiparams, **params): return self.execute(statement, *multiparams, **params).scalar() def _execute_clauseelement(self, elem, multiparams=None, params=None): connection = self.contextual_connect(close_with_result=True) return connection._execute_clauseelement(elem, multiparams, params) def _execute_compiled(self, compiled, multiparams, params): connection = self.contextual_connect(close_with_result=True) return connection._execute_compiled(compiled, multiparams, params) def connect(self, **kwargs): """Return a new :class:`.Connection` object. The :class:`.Connection` object is a facade that uses a DBAPI connection internally in order to communicate with the database. This connection is procured from the connection-holding :class:`.Pool` referenced by this :class:`.Engine`. When the :meth:`~.Connection.close` method of the :class:`.Connection` object is called, the underlying DBAPI connection is then returned to the connection pool, where it may be used again in a subsequent call to :meth:`~.Engine.connect`. """ return self._connection_cls(self, **kwargs) def contextual_connect(self, close_with_result=False, **kwargs): """Return a :class:`.Connection` object which may be part of some ongoing context. By default, this method does the same thing as :meth:`.Engine.connect`. Subclasses of :class:`.Engine` may override this method to provide contextual behavior. :param close_with_result: When True, the first :class:`.ResultProxy` created by the :class:`.Connection` will call the :meth:`.Connection.close` method of that connection as soon as any pending result rows are exhausted. This is used to supply the "connectionless execution" behavior provided by the :meth:`.Engine.execute` method. """ return self._connection_cls(self, self.pool.connect(), close_with_result=close_with_result, **kwargs) def table_names(self, schema=None, connection=None): """Return a list of all table names available in the database. :param schema: Optional, retrieve names from a non-default schema. :param connection: Optional, use a specified connection. Default is the ``contextual_connect`` for this ``Engine``. """ if connection is None: conn = self.contextual_connect() else: conn = connection if not schema: schema = self.dialect.default_schema_name try: return self.dialect.get_table_names(conn, schema) finally: if connection is None: conn.close() @util.deprecated("0.7", "Use autoload=True with :class:`.Table`, " "or use the :class:`.Inspector` object.") def reflecttable(self, table, connection=None, include_columns=None): """Load table description from the database. Uses the given :class:`.Connection`, or if None produces its own :class:`.Connection`, and passes the ``table`` and ``include_columns`` arguments onto that :class:`.Connection` object's :meth:`.Connection.reflecttable` method. The :class:`.Table` object is then populated with new attributes. """ if connection is None: conn = self.contextual_connect() else: conn = connection try: self.dialect.reflecttable(conn, table, include_columns) finally: if connection is None: conn.close() def has_table(self, table_name, schema=None): return self.run_callable(self.dialect.has_table, table_name, schema) def raw_connection(self): """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. In most situations, the :class:`.Connection` object should be used, which is procured using the :meth:`.Engine.connect` method. """ return self.pool.unique_connection() # This reconstructor is necessary so that pickles with the C extension or # without use the same Binary format. try: # We need a different reconstructor on the C extension so that we can # add extra checks that fields have correctly been initialized by # __setstate__. from sqlalchemy.cresultproxy import safe_rowproxy_reconstructor # The extra function embedding is needed so that the # reconstructor function has the same signature whether or not # the extension is present. def rowproxy_reconstructor(cls, state): return safe_rowproxy_reconstructor(cls, state) except ImportError: def rowproxy_reconstructor(cls, state): obj = cls.__new__(cls) obj.__setstate__(state) return obj try: from sqlalchemy.cresultproxy import BaseRowProxy except ImportError: class BaseRowProxy(object): __slots__ = ('_parent', '_row', '_processors', '_keymap') def __init__(self, parent, row, processors, keymap): """RowProxy objects are constructed by ResultProxy objects.""" self._parent = parent self._row = row self._processors = processors self._keymap = keymap def __reduce__(self): return (rowproxy_reconstructor, (self.__class__, self.__getstate__())) def values(self): """Return the values represented by this RowProxy as a list.""" return list(self) def __iter__(self): for processor, value in izip(self._processors, self._row): if processor is None: yield value else: yield processor(value) def __len__(self): return len(self._row) def __getitem__(self, key): try: processor, obj, index = self._keymap[key] except KeyError: processor, obj, index = self._parent._key_fallback(key) except TypeError: if isinstance(key, slice): l = [] for processor, value in izip(self._processors[key], self._row[key]): if processor is None: l.append(value) else: l.append(processor(value)) return tuple(l) else: raise if index is None: raise exc.InvalidRequestError( "Ambiguous column name '%s' in result set! " "try 'use_labels' option on select statement." % key) if processor is not None: return processor(self._row[index]) else: return self._row[index] def __getattr__(self, name): try: # TODO: no test coverage here return self[name] except KeyError, e: raise AttributeError(e.args[0]) class RowProxy(BaseRowProxy): """Proxy values from a single cursor row. Mostly follows "ordered dictionary" behavior, mapping result values to the string-based column name, the integer position of the result in the row, as well as Column instances which can be mapped to the original Columns that produced this result set (for results that correspond to constructed SQL expressions). """ __slots__ = () def __contains__(self, key): return self._parent._has_key(self._row, key) def __getstate__(self): return { '_parent': self._parent, '_row': tuple(self) } def __setstate__(self, state): self._parent = parent = state['_parent'] self._row = state['_row'] self._processors = parent._processors self._keymap = parent._keymap __hash__ = None def __eq__(self, other): return other is self or other == tuple(self) def __ne__(self, other): return not self.__eq__(other) def __repr__(self): return repr(tuple(self)) def has_key(self, key): """Return True if this RowProxy contains the given key.""" return self._parent._has_key(self._row, key) def items(self): """Return a list of tuples, each tuple containing a key/value pair.""" # TODO: no coverage here return [(key, self[key]) for key in self.iterkeys()] def keys(self): """Return the list of keys as strings represented by this RowProxy.""" return self._parent.keys def iterkeys(self): return iter(self._parent.keys) def itervalues(self): return iter(self) try: # Register RowProxy with Sequence, # so sequence protocol is implemented from collections import Sequence Sequence.register(RowProxy) except ImportError: pass class ResultMetaData(object): """Handle cursor.description, applying additional info from an execution context.""" def __init__(self, parent, metadata): self._processors = processors = [] # We do not strictly need to store the processor in the key mapping, # though it is faster in the Python version (probably because of the # saved attribute lookup self._processors) self._keymap = keymap = {} self.keys = [] context = parent.context dialect = context.dialect typemap = dialect.dbapi_type_map for i, rec in enumerate(metadata): colname = rec[0] coltype = rec[1] if dialect.description_encoding: colname = dialect._description_decoder(colname) if context.result_map: try: name, obj, type_ = context.result_map[colname.lower()] except KeyError: name, obj, type_ = \ colname, None, typemap.get(coltype, types.NULLTYPE) else: name, obj, type_ = \ colname, None, typemap.get(coltype, types.NULLTYPE) processor = type_._cached_result_processor(dialect, coltype) processors.append(processor) rec = (processor, obj, i) # indexes as keys. This is only needed for the Python version of # RowProxy (the C version uses a faster path for integer indexes). keymap[i] = rec # Column names as keys if keymap.setdefault(name.lower(), rec) is not rec: # We do not raise an exception directly because several # columns colliding by name is not a problem as long as the # user does not try to access them (ie use an index directly, # or the more precise ColumnElement) keymap[name.lower()] = (processor, obj, None) if dialect.requires_name_normalize: colname = dialect.normalize_name(colname) self.keys.append(colname) if obj: for o in obj: keymap[o] = rec if parent._echo: context.engine.logger.debug( "Col %r", tuple(x[0] for x in metadata)) def _set_keymap_synonym(self, name, origname): """Set a synonym for the given name. Some dialects (SQLite at the moment) may use this to adjust the column names that are significant within a row. """ rec = (processor, obj, i) = self._keymap[origname.lower()] if self._keymap.setdefault(name, rec) is not rec: self._keymap[name] = (processor, obj, None) def _key_fallback(self, key, raiseerr=True): map = self._keymap result = None if isinstance(key, basestring): result = map.get(key.lower()) # fallback for targeting a ColumnElement to a textual expression # this is a rare use case which only occurs when matching text() # or colummn('name') constructs to ColumnElements, or after a # pickle/unpickle roundtrip elif isinstance(key, expression.ColumnElement): if key._label and key._label.lower() in map: result = map[key._label.lower()] elif hasattr(key, 'name') and key.name.lower() in map: # match is only on name. result = map[key.name.lower()] # search extra hard to make sure this # isn't a column/label name overlap. # this check isn't currently available if the row # was unpickled. if result is not None and \ result[1] is not None: for obj in result[1]: if key._compare_name_for_result(obj): break else: result = None if result is None: if raiseerr: raise exc.NoSuchColumnError( "Could not locate column in row for column '%s'" % expression._string_or_unprintable(key)) else: return None else: map[key] = result return result def _has_key(self, row, key): if key in self._keymap: return True else: return self._key_fallback(key, False) is not None def __getstate__(self): return { '_pickled_keymap': dict( (key, index) for key, (processor, obj, index) in self._keymap.iteritems() if isinstance(key, (basestring, int)) ), 'keys': self.keys } def __setstate__(self, state): # the row has been processed at pickling time so we don't need any # processor anymore self._processors = [None for _ in xrange(len(state['keys']))] self._keymap = keymap = {} for key, index in state['_pickled_keymap'].iteritems(): # not preserving "obj" here, unfortunately our # proxy comparison fails with the unpickle keymap[key] = (None, None, index) self.keys = state['keys'] self._echo = False class ResultProxy(object): """Wraps a DB-API cursor object to provide easier access to row columns. Individual columns may be accessed by their integer position, case-insensitive column name, or by ``schema.Column`` object. e.g.:: row = fetchone() col1 = row[0] # access via integer position col2 = row['col2'] # access via name col3 = row[mytable.c.mycol] # access via Column object. ``ResultProxy`` also handles post-processing of result column data using ``TypeEngine`` objects, which are referenced from the originating SQL statement that produced this result set. """ _process_row = RowProxy out_parameters = None _can_close_connection = False def __init__(self, context): self.context = context self.dialect = context.dialect self.closed = False self.cursor = self._saved_cursor = context.cursor self.connection = context.root_connection self._echo = self.connection._echo and \ context.engine._should_log_debug() self._init_metadata() def _init_metadata(self): metadata = self._cursor_description() if metadata is None: self._metadata = None else: self._metadata = ResultMetaData(self, metadata) def keys(self): """Return the current set of string keys for rows.""" if self._metadata: return self._metadata.keys else: return [] @util.memoized_property def rowcount(self): """Return the 'rowcount' for this result. The 'rowcount' reports the number of rows affected by an UPDATE or DELETE statement. It has *no* other uses and is not intended to provide the number of rows present from a SELECT. Note that this row count may not be properly implemented in some dialects; this is indicated by :meth:`~sqlalchemy.engine.base.ResultProxy.supports_sane_rowcount()` and :meth:`~sqlalchemy.engine.base.ResultProxy.supports_sane_multi_rowcount()`. ``rowcount()`` also may not work at this time for a statement that uses ``returning()``. """ try: return self.context.rowcount except Exception, e: self.connection._handle_dbapi_exception( e, None, None, self.cursor, self.context) raise @property def lastrowid(self): """return the 'lastrowid' accessor on the DBAPI cursor. This is a DBAPI specific method and is only functional for those backends which support it, for statements where it is appropriate. It's behavior is not consistent across backends. Usage of this method is normally unnecessary; the :attr:`~ResultProxy.inserted_primary_key` attribute provides a tuple of primary key values for a newly inserted row, regardless of database backend. """ try: return self._saved_cursor.lastrowid except Exception, e: self.connection._handle_dbapi_exception( e, None, None, self._saved_cursor, self.context) raise @property def returns_rows(self): """True if this :class:`.ResultProxy` returns rows. I.e. if it is legal to call the methods :meth:`~.ResultProxy.fetchone`, :meth:`~.ResultProxy.fetchmany` :meth:`~.ResultProxy.fetchall`. """ return self._metadata is not None @property def is_insert(self): """True if this :class:`.ResultProxy` is the result of a executing an expression language compiled :func:`.expression.insert` construct. When True, this implies that the :attr:`inserted_primary_key` attribute is accessible, assuming the statement did not include a user defined "returning" construct. """ return self.context.isinsert def _cursor_description(self): """May be overridden by subclasses.""" return self._saved_cursor.description def close(self, _autoclose_connection=True): """Close this ResultProxy. Closes the underlying DBAPI cursor corresponding to the execution. Note that any data cached within this ResultProxy is still available. For some types of results, this may include buffered rows. If this ResultProxy was generated from an implicit execution, the underlying Connection will also be closed (returns the underlying DBAPI connection to the connection pool.) This method is called automatically when: * all result rows are exhausted using the fetchXXX() methods. * cursor.description is None. """ if not self.closed: self.closed = True self.connection._safe_close_cursor(self.cursor) if _autoclose_connection and \ self.connection.should_close_with_result: self.connection.close() # allow consistent errors self.cursor = None def __iter__(self): while True: row = self.fetchone() if row is None: raise StopIteration else: yield row @util.memoized_property def inserted_primary_key(self): """Return the primary key for the row just inserted. The return value is a list of scalar values corresponding to the list of primary key columns in the target table. This only applies to single row :func:`.insert` constructs which did not explicitly specify :meth:`.Insert.returning`. Note that primary key columns which specify a server_default clause, or otherwise do not qualify as "autoincrement" columns (see the notes at :class:`.Column`), and were generated using the database-side default, will appear in this list as ``None`` unless the backend supports "returning" and the insert statement executed with the "implicit returning" enabled. """ if not self.context.isinsert: raise exc.InvalidRequestError( "Statement is not an insert() expression construct.") elif self.context._is_explicit_returning: raise exc.InvalidRequestError( "Can't call inserted_primary_key when returning() " "is used.") return self.context.inserted_primary_key @util.deprecated("0.6", "Use :attr:`.ResultProxy.inserted_primary_key`") def last_inserted_ids(self): """Return the primary key for the row just inserted.""" return self.inserted_primary_key def last_updated_params(self): """Return the collection of updated parameters from this execution. """ if self.context.executemany: return self.context.compiled_parameters else: return self.context.compiled_parameters[0] def last_inserted_params(self): """Return the collection of inserted parameters from this execution. """ if self.context.executemany: return self.context.compiled_parameters else: return self.context.compiled_parameters[0] def lastrow_has_defaults(self): """Return ``lastrow_has_defaults()`` from the underlying ExecutionContext. See ExecutionContext for details. """ return self.context.lastrow_has_defaults() def postfetch_cols(self): """Return ``postfetch_cols()`` from the underlying ExecutionContext. See ExecutionContext for details. """ return self.context.postfetch_cols def prefetch_cols(self): return self.context.prefetch_cols def supports_sane_rowcount(self): """Return ``supports_sane_rowcount`` from the dialect.""" return self.dialect.supports_sane_rowcount def supports_sane_multi_rowcount(self): """Return ``supports_sane_multi_rowcount`` from the dialect.""" return self.dialect.supports_sane_multi_rowcount def _fetchone_impl(self): try: return self.cursor.fetchone() except AttributeError: self._non_result() def _fetchmany_impl(self, size=None): try: if size is None: return self.cursor.fetchmany() else: return self.cursor.fetchmany(size) except AttributeError: self._non_result() def _fetchall_impl(self): try: return self.cursor.fetchall() except AttributeError: self._non_result() def _non_result(self): if self._metadata is None: raise exc.ResourceClosedError( "This result object does not return rows. " "It has been closed automatically.", ) else: raise exc.ResourceClosedError("This result object is closed.") def process_rows(self, rows): process_row = self._process_row metadata = self._metadata keymap = metadata._keymap processors = metadata._processors if self._echo: log = self.context.engine.logger.debug l = [] for row in rows: log("Row %r", row) l.append(process_row(metadata, row, processors, keymap)) return l else: return [process_row(metadata, row, processors, keymap) for row in rows] def fetchall(self): """Fetch all rows, just like DB-API ``cursor.fetchall()``.""" try: l = self.process_rows(self._fetchall_impl()) self.close() return l except Exception, e: self.connection._handle_dbapi_exception( e, None, None, self.cursor, self.context) raise def fetchmany(self, size=None): """Fetch many rows, just like DB-API ``cursor.fetchmany(size=cursor.arraysize)``. If rows are present, the cursor remains open after this is called. Else the cursor is automatically closed and an empty list is returned. """ try: l = self.process_rows(self._fetchmany_impl(size)) if len(l) == 0: self.close() return l except Exception, e: self.connection._handle_dbapi_exception( e, None, None, self.cursor, self.context) raise def fetchone(self): """Fetch one row, just like DB-API ``cursor.fetchone()``. If a row is present, the cursor remains open after this is called. Else the cursor is automatically closed and None is returned. """ try: row = self._fetchone_impl() if row is not None: return self.process_rows([row])[0] else: self.close() return None except Exception, e: self.connection._handle_dbapi_exception( e, None, None, self.cursor, self.context) raise def first(self): """Fetch the first row and then close the result set unconditionally. Returns None if no row is present. """ if self._metadata is None: self._non_result() try: row = self._fetchone_impl() except Exception, e: self.connection._handle_dbapi_exception( e, None, None, self.cursor, self.context) raise try: if row is not None: return self.process_rows([row])[0] else: return None finally: self.close() def scalar(self): """Fetch the first column of the first row, and close the result set. Returns None if no row is present. """ row = self.first() if row is not None: return row[0] else: return None class BufferedRowResultProxy(ResultProxy): """A ResultProxy with row buffering behavior. ``ResultProxy`` that buffers the contents of a selection of rows before ``fetchone()`` is called. This is to allow the results of ``cursor.description`` to be available immediately, when interfacing with a DB-API that requires rows to be consumed before this information is available (currently psycopg2, when used with server-side cursors). The pre-fetching behavior fetches only one row initially, and then grows its buffer size by a fixed amount with each successive need for additional rows up to a size of 100. """ def _init_metadata(self): self.__buffer_rows() super(BufferedRowResultProxy, self)._init_metadata() # this is a "growth chart" for the buffering of rows. # each successive __buffer_rows call will use the next # value in the list for the buffer size until the max # is reached size_growth = { 1 : 5, 5 : 10, 10 : 20, 20 : 50, 50 : 100, 100 : 250, 250 : 500, 500 : 1000 } def __buffer_rows(self): size = getattr(self, '_bufsize', 1) self.__rowbuffer = collections.deque(self.cursor.fetchmany(size)) self._bufsize = self.size_growth.get(size, size) def _fetchone_impl(self): if self.closed: return None if not self.__rowbuffer: self.__buffer_rows() if not self.__rowbuffer: return None return self.__rowbuffer.popleft() def _fetchmany_impl(self, size=None): if size is None: return self._fetchall_impl() result = [] for x in range(0, size): row = self._fetchone_impl() if row is None: break result.append(row) return result def _fetchall_impl(self): self.__rowbuffer.extend(self.cursor.fetchall()) ret = self.__rowbuffer self.__rowbuffer = collections.deque() return ret class FullyBufferedResultProxy(ResultProxy): """A result proxy that buffers rows fully upon creation. Used for operations where a result is to be delivered after the database conversation can not be continued, such as MSSQL INSERT...OUTPUT after an autocommit. """ def _init_metadata(self): super(FullyBufferedResultProxy, self)._init_metadata() self.__rowbuffer = self._buffer_rows() def _buffer_rows(self): return collections.deque(self.cursor.fetchall()) def _fetchone_impl(self): if self.__rowbuffer: return self.__rowbuffer.popleft() else: return None def _fetchmany_impl(self, size=None): if size is None: return self._fetchall_impl() result = [] for x in range(0, size): row = self._fetchone_impl() if row is None: break result.append(row) return result def _fetchall_impl(self): ret = self.__rowbuffer self.__rowbuffer = collections.deque() return ret class BufferedColumnRow(RowProxy): def __init__(self, parent, row, processors, keymap): # preprocess row row = list(row) # this is a tad faster than using enumerate index = 0 for processor in parent._orig_processors: if processor is not None: row[index] = processor(row[index]) index += 1 row = tuple(row) super(BufferedColumnRow, self).__init__(parent, row, processors, keymap) class BufferedColumnResultProxy(ResultProxy): """A ResultProxy with column buffering behavior. ``ResultProxy`` that loads all columns into memory each time fetchone() is called. If fetchmany() or fetchall() are called, the full grid of results is fetched. This is to operate with databases where result rows contain "live" results that fall out of scope unless explicitly fetched. Currently this includes cx_Oracle LOB objects. """ _process_row = BufferedColumnRow def _init_metadata(self): super(BufferedColumnResultProxy, self)._init_metadata() metadata = self._metadata # orig_processors will be used to preprocess each row when they are # constructed. metadata._orig_processors = metadata._processors # replace the all type processors by None processors. metadata._processors = [None for _ in xrange(len(metadata.keys))] keymap = {} for k, (func, obj, index) in metadata._keymap.iteritems(): keymap[k] = (None, obj, index) self._metadata._keymap = keymap def fetchall(self): # can't call cursor.fetchall(), since rows must be # fully processed before requesting more from the DBAPI. l = [] while True: row = self.fetchone() if row is None: break l.append(row) return l def fetchmany(self, size=None): # can't call cursor.fetchmany(), since rows must be # fully processed before requesting more from the DBAPI. if size is None: return self.fetchall() l = [] for i in xrange(size): row = self.fetchone() if row is None: break l.append(row) return l def connection_memoize(key): """Decorator, memoize a function in a connection.info stash. Only applicable to functions which take no arguments other than a connection. The memo will be stored in ``connection.info[key]``. """ @util.decorator def decorated(fn, self, connection): connection = connection.connect() try: return connection.info[key] except KeyError: connection.info[key] = val = fn(self, connection) return val return decorated