# engine/base.py # Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Michael Bayer mike_mp@zzzcomputing.com # # 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 from sqlalchemy.sql import expression 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:`~sqlalchemy.engine.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:`~sqlalchemy.engine.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:`~sqlalchemy.engine.Connection`, a string `table_name`, and an optional string `schema`, return primary key information as a list of column names. """ raise NotImplementedError() def get_foreign_keys(self, connection, table_name, schema=None, **kw): """Return information about foreign_keys in `table_name`. Given a :class:`~sqlalchemy.engine.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:`~sqlalchemy.engine.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:`~sqlalchemy.engine.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:`~sqlalchemy.engine.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:`~sqlalchemy.engine.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): """Return True if the given DB-API error indicates an invalid connection""" raise NotImplementedError() def on_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 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 occured 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 last_inserted_params(self): """Return a dictionary of the full parameter dictionary for the last compiled INSERT statement. Includes any ColumnDefaults or Sequences that were pre-executed. """ raise NotImplementedError() def last_updated_params(self): """Return a dictionary of the full parameter dictionary for the last compiled UPDATE statement. Includes any ColumnDefaults that were pre-executed. """ 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.statement = statement self.bind = bind self.can_execute = statement.supports_execution def compile(self): """Produce the internal string representation of this element.""" self.string = self.process(self.statement) @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 ``Connectable`` are :class:`Connection` and :class:`Engine`. Connectable must also implement the 'dialect' member which references a :class:`Dialect` instance. """ def contextual_connect(self): """Return a Connection object which may be part of an ongoing context.""" raise NotImplementedError() def create(self, entity, **kwargs): """Create a table or index given an appropriate schema object.""" raise NotImplementedError() def drop(self, entity, **kwargs): """Drop a table or index given an appropriate schema object.""" raise NotImplementedError() def execute(self, object, *multiparams, **params): 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 ClauseElement, Compiled and DefaultGenerator objects. Provides a begin method to return Transaction objects. The Connection object is **not** thread-safe. .. index:: single: thread safety; Connection """ _execution_options = util.frozendict() def __init__(self, engine, connection=None, close_with_result=False, _branch=False, _execution_options=None): """Construct a new Connection. Connection objects are typically constructed by an :class:`~sqlalchemy.engine.Engine`, see the ``connect()`` and ``contextual_connect()`` methods of Engine. """ self.engine = engine 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._echo = self.engine._should_log_info() if _execution_options: self._execution_options = self._execution_options.union(_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(self.engine, self.__connection, _branch=True) 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) The options are the same as those accepted by :meth:`sqlalchemy.sql.expression.Executable.execution_options`. """ return self.engine.Connection( self.engine, self.__connection, _branch=self.__branch, _execution_options=opt) @property def dialect(self): "Dialect used by this Connection." return self.engine.dialect @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: 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.InvalidRequestError("This Connection is closed") @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.closed: raise exc.InvalidRequestError("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. 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. """ 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. 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. """ 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. :param xid: the two phase transaction id. If not supplied, a random id will be generated. """ 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") 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): # use getattr() for is_valid to support exceptions raised in dialect initializer, # where we do not yet have the pool wrappers plugged in if not self.closed and not self.invalidated and \ getattr(self.__connection, 'is_valid', False): 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._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 name is None: self.__savepoint_seq += 1 name = 'sa_savepoint_%s' % self.__savepoint_seq if self.__connection.is_valid: self.engine.dialect.do_savepoint(self, name) return name def _rollback_to_savepoint_impl(self, name, context): if self.__connection.is_valid: self.engine.dialect.do_rollback_to_savepoint(self, name) self.__transaction = context def _release_savepoint_impl(self, name, context): if self.__connection.is_valid: self.engine.dialect.do_release_savepoint(self, name) self.__transaction = context def _begin_twophase_impl(self, xid): if self.__connection.is_valid: self.engine.dialect.do_begin_twophase(self, xid) def _prepare_twophase_impl(self, xid): if self.__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.__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.__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 Connection.""" 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 and returns a ResultProxy.""" 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: " + str(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): return self._execute_clauseelement(func.select(), multiparams, params) def _execute_default(self, default, multiparams, params): ctx = self.__create_execution_context() ret = ctx._exec_default(default) if self.should_close_with_result: self.close() return ret def _execute_ddl(self, ddl, params, multiparams): context = self.__create_execution_context( compiled_ddl=ddl.compile(dialect=self.dialect), parameters=None ) return self.__execute_context(context) def _execute_clauseelement(self, elem, multiparams, params): params = self.__distill_params(multiparams, params) if params: keys = params[0].keys() else: keys = [] context = self.__create_execution_context( compiled_sql=elem.compile( dialect=self.dialect, column_keys=keys, inline=len(params) > 1), parameters=params ) return self.__execute_context(context) def _execute_compiled(self, compiled, multiparams, params): """Execute a sql.Compiled object.""" context = self.__create_execution_context( compiled_sql=compiled, parameters=self.__distill_params(multiparams, params) ) return self.__execute_context(context) def _execute_text(self, statement, multiparams, params): parameters = self.__distill_params(multiparams, params) context = self.__create_execution_context(statement=statement, parameters=parameters) return self.__execute_context(context) def __execute_context(self, context): if context.compiled: context.pre_exec() if context.executemany: self._cursor_executemany( context.cursor, context.statement, context.parameters, context=context) else: self._cursor_execute( context.cursor, context.statement, context.parameters[0], context=context) 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 r = context.get_result_proxy()._autoclose() if self.__transaction is None and context.should_autocommit: self._commit_impl() if r.closed and self.should_close_with_result: self.close() return r def _handle_dbapi_exception(self, e, statement, parameters, cursor, context): if getattr(self, '_reentrant_error', False): # Py3K #raise exc.DBAPIError.instance(statement, parameters, e) from e # Py2K raise exc.DBAPIError.instance(statement, parameters, e), None, sys.exc_info()[2] # end Py2K self._reentrant_error = True try: if not isinstance(e, self.dialect.dbapi.Error): return if context: context.handle_dbapi_exception(e) is_disconnect = self.dialect.is_disconnect(e) if is_disconnect: self.invalidate(e) self.engine.dispose() else: if cursor: cursor.close() self._autorollback() if self.should_close_with_result: self.close() # Py3K #raise exc.DBAPIError.instance(statement, parameters, e, connection_invalidated=is_disconnect) from e # Py2K raise exc.DBAPIError.instance(statement, parameters, e, connection_invalidated=is_disconnect), None, sys.exc_info()[2] # end Py2K finally: del self._reentrant_error def __create_execution_context(self, **kwargs): try: dialect = self.engine.dialect return dialect.execution_ctx_cls(dialect, connection=self, **kwargs) except Exception, e: self._handle_dbapi_exception(e, kwargs.get('statement', None), kwargs.get('parameters', None), None, None) raise def _cursor_execute(self, cursor, statement, parameters, context=None): if self._echo: self.engine.logger.info(statement) self.engine.logger.info("%r", parameters) try: self.dialect.do_execute(cursor, statement, parameters, context=context) except Exception, e: self._handle_dbapi_exception(e, statement, parameters, cursor, context) raise def _cursor_executemany(self, cursor, statement, parameters, context=None): if self._echo: self.engine.logger.info(statement) self.engine.logger.info("%r", parameters) try: self.dialect.do_executemany(cursor, statement, parameters, context=context) except Exception, e: self._handle_dbapi_exception(e, statement, parameters, cursor, context) raise # 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 } def create(self, entity, **kwargs): """Create a Table or Index given an appropriate Schema object.""" return self.engine.create(entity, connection=self, **kwargs) def drop(self, entity, **kwargs): """Drop a Table or Index given an appropriate Schema object.""" return self.engine.drop(entity, connection=self, **kwargs) def reflecttable(self, table, include_columns=None): """Reflect the columns in the given string table name from the database.""" 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. This is a shortcut for explicitly calling `begin()` and `commit()` and optionally `rollback()` when exceptions are raised. The given `*args` and `**kwargs` will be passed to the function. See also transaction() on engine. """ 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): return callable_(self, *args, **kwargs) class Transaction(object): """Represent a Transaction in progress. The Transaction object is **not** threadsafe. .. 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 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): if not self._parent.is_active: return self._do_rollback() self.is_active = False def _do_rollback(self): self._parent.rollback() def commit(self): 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: self.commit() 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): 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): 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): 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. """ def __init__(self, pool, dialect, url, logging_name=None, echo=None, proxy=None): self.pool = pool self.url = url self.dialect = dialect if logging_name: self.logging_name = logging_name self.echo = echo self.engine = self self.logger = log.instance_logger(self, echoflag=echo) if proxy: self.Connection = _proxy_connection_cls(Connection, proxy) else: self.Connection = Connection @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): self.pool.dispose() self.pool = self.pool.recreate() def create(self, entity, connection=None, **kwargs): """Create a table or index within this engine's database connection given a schema.Table object.""" from sqlalchemy.engine import ddl self._run_visitor(ddl.SchemaGenerator, entity, connection=connection, **kwargs) def drop(self, entity, connection=None, **kwargs): """Drop a table or index within this engine's database connection given a schema.Table object.""" 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 def func(self): return expression._FunctionGenerator(bind=self) def text(self, text, *args, **kwargs): """Return a sql.text() object for performing literal queries.""" 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: visitorcallable(self.dialect, conn, **kwargs).traverse(element) finally: if connection is None: conn.close() def transaction(self, callable_, *args, **kwargs): """Execute the given function within a transaction boundary. This is a shortcut for explicitly calling `begin()` and `commit()` and optionally `rollback()` when exceptions are raised. The given `*args` and `**kwargs` will be passed to the function. The connection used is that of contextual_connect(). See also the similar method on Connection itself. """ conn = self.contextual_connect() try: return conn.transaction(callable_, *args, **kwargs) finally: conn.close() def run_callable(self, callable_, *args, **kwargs): conn = self.contextual_connect() try: return conn.run_callable(callable_, *args, **kwargs) finally: conn.close() def execute(self, statement, *multiparams, **params): 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 newly allocated Connection object.""" return self.Connection(self, **kwargs) def contextual_connect(self, close_with_result=False, **kwargs): """Return a Connection object which may be newly allocated, or may be part of some ongoing context. This Connection is meant to be used by the various "auto-connecting" operations. """ return self.Connection(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() def reflecttable(self, table, connection=None, include_columns=None): """Given a Table object, reflects its columns and properties from the database.""" 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 DB-API connection.""" return self.pool.unique_connection() def _proxy_connection_cls(cls, proxy): class ProxyConnection(cls): def execute(self, object, *multiparams, **params): return proxy.execute(self, super(ProxyConnection, self).execute, object, *multiparams, **params) def _execute_clauseelement(self, elem, multiparams=None, params=None): return proxy.execute(self, super(ProxyConnection, self).execute, elem, *(multiparams or []), **(params or {})) def _cursor_execute(self, cursor, statement, parameters, context=None): return proxy.cursor_execute(super(ProxyConnection, self)._cursor_execute, cursor, statement, parameters, context, False) def _cursor_executemany(self, cursor, statement, parameters, context=None): return proxy.cursor_execute(super(ProxyConnection, self)._cursor_executemany, cursor, statement, parameters, context, True) def _begin_impl(self): return proxy.begin(self, super(ProxyConnection, self)._begin_impl) def _rollback_impl(self): return proxy.rollback(self, super(ProxyConnection, self)._rollback_impl) def _commit_impl(self): return proxy.commit(self, super(ProxyConnection, self)._commit_impl) def _savepoint_impl(self, name=None): return proxy.savepoint(self, super(ProxyConnection, self)._savepoint_impl, name=name) def _rollback_to_savepoint_impl(self, name, context): return proxy.rollback_savepoint(self, super(ProxyConnection, self)._rollback_to_savepoint_impl, name, context) def _release_savepoint_impl(self, name, context): return proxy.release_savepoint(self, super(ProxyConnection, self)._release_savepoint_impl, name, context) def _begin_twophase_impl(self, xid): return proxy.begin_twophase(self, super(ProxyConnection, self)._begin_twophase_impl, xid) def _prepare_twophase_impl(self, xid): return proxy.prepare_twophase(self, super(ProxyConnection, self)._prepare_twophase_impl, xid) def _rollback_twophase_impl(self, xid, is_prepared): return proxy.rollback_twophase(self, super(ProxyConnection, self)._rollback_twophase_impl, xid, is_prepared) def _commit_twophase_impl(self, xid, is_prepared): return proxy.commit_twophase(self, super(ProxyConnection, self)._commit_twophase_impl, xid, is_prepared) return ProxyConnection # 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, index = self._keymap[key] except KeyError: processor, 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) 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 = [] self._echo = parent._echo context = parent.context dialect = context.dialect typemap = dialect.dbapi_type_map for i, (colname, coltype) in enumerate(m[0:2] for m in metadata): if dialect.description_encoding: colname = colname.decode(dialect.description_encoding) if '.' in colname: # sqlite will in some circumstances prepend table name to # colnames, so strip origname = colname colname = colname.split('.')[-1] else: origname = None 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_.dialect_impl(dialect).\ result_processor(dialect, coltype) processors.append(processor) rec = (processor, 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, None) # store the "origname" if we truncated (sqlite only) if origname and \ keymap.setdefault(origname.lower(), rec) is not rec: keymap[origname.lower()] = (processor, 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 self._echo: self.logger = context.engine.logger self.logger.debug( "Col %r", tuple(x[0] for x in metadata)) def _key_fallback(self, key): 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() # constructs to ColumnElements, and 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: result = map[key.name.lower()] if result is None: raise exc.NoSuchColumnError( "Could not locate column in row for column '%s'" % key) else: map[key] = result return result def _has_key(self, row, key): if key in self._keymap: return True else: try: self._key_fallback(key) return True except exc.NoSuchColumnError: return False def __len__(self): return len(self.keys) def __getstate__(self): return { '_pickled_keymap': dict( (key, index) for key, (processor, 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(): keymap[key] = (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 = 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()``. """ return self.context.rowcount @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 inserted_primary_key method provides a tuple of primary key values for a newly inserted row, regardless of database backend. """ return self.cursor.lastrowid def _cursor_description(self): """May be overridden by subclasses.""" return self.cursor.description def _autoclose(self): """called by the Connection to autoclose cursors that have no pending results beyond those used by an INSERT/UPDATE/DELETE with no explicit RETURNING clause. """ if self.context.isinsert: if self.context._is_implicit_returning: self.context._fetch_implicit_returning(self) self.close(_autoclose_connection=False) elif not self.context._is_explicit_returning: self.close(_autoclose_connection=False) elif self._metadata is None: # no results, get rowcount # (which requires open cursor on some drivers # such as kintersbasdb, mxodbc), self.rowcount self.close(_autoclose_connection=False) return self 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.cursor.close() if _autoclose_connection and \ self.connection.should_close_with_result: self.connection.close() 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. This only applies to single row insert() constructs which did not explicitly specify returning(). """ 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("Use inserted_primary_key") def last_inserted_ids(self): """deprecated. use inserted_primary_key.""" return self.inserted_primary_key def last_updated_params(self): """Return ``last_updated_params()`` from the underlying ExecutionContext. See ExecutionContext for details. """ return self.context.last_updated_params() def last_inserted_params(self): """Return ``last_inserted_params()`` from the underlying ExecutionContext. See ExecutionContext for details. """ return self.context.last_inserted_params() 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): return self.cursor.fetchone() def _fetchmany_impl(self, size=None): return self.cursor.fetchmany(size) def _fetchall_impl(self): return self.cursor.fetchall() 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. """ 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 } def __buffer_rows(self): size = getattr(self, '_bufsize', 1) self.__rowbuffer = self.cursor.fetchmany(size) self._bufsize = self.size_growth.get(size, size) def _fetchone_impl(self): if self.closed: return None if len(self.__rowbuffer) == 0: self.__buffer_rows() if len(self.__rowbuffer) == 0: return None return self.__rowbuffer.pop(0) def _fetchmany_impl(self, size=None): 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 + list(self.cursor.fetchall()) self.__rowbuffer[:] = [] 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 self.cursor.fetchall() def _fetchone_impl(self): if self.__rowbuffer: return self.__rowbuffer.pop(0) else: return None def _fetchmany_impl(self, size=None): 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 = [] 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, index) in metadata._keymap.iteritems(): keymap[k] = (None, 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