mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-06-05 07:17:06 -04:00
Mike Bayer
c38e5d043f
to be based solely on presence of cursor.description. All the regexp-based guessing about statements returning rows has been removed [ticket:1212].
374 lines
14 KiB
Python
374 lines
14 KiB
Python
# engine/default.py
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# Copyright (C) 2005, 2006, 2007, 2008 Michael Bayer mike_mp@zzzcomputing.com
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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"""Default implementations of per-dialect sqlalchemy.engine classes.
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These are semi-private implementation classes which are only of importance
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to database dialect authors; dialects will usually use the classes here
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as the base class for their own corresponding classes.
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"""
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import re, random
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from sqlalchemy.engine import base
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from sqlalchemy.sql import compiler, expression
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from sqlalchemy import exc
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AUTOCOMMIT_REGEXP = re.compile(r'\s*(?:UPDATE|INSERT|CREATE|DELETE|DROP|ALTER)',
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re.I | re.UNICODE)
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class DefaultDialect(base.Dialect):
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"""Default implementation of Dialect"""
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schemagenerator = compiler.SchemaGenerator
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schemadropper = compiler.SchemaDropper
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statement_compiler = compiler.DefaultCompiler
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preparer = compiler.IdentifierPreparer
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defaultrunner = base.DefaultRunner
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supports_alter = True
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supports_unicode_statements = False
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max_identifier_length = 9999
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supports_sane_rowcount = True
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supports_sane_multi_rowcount = True
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preexecute_pk_sequences = False
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supports_pk_autoincrement = True
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dbapi_type_map = {}
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default_paramstyle = 'named'
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supports_default_values = False
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supports_empty_insert = True
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def __init__(self, convert_unicode=False, assert_unicode=False, encoding='utf-8', paramstyle=None, dbapi=None, **kwargs):
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self.convert_unicode = convert_unicode
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self.assert_unicode = assert_unicode
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self.encoding = encoding
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self.positional = False
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self._ischema = None
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self.dbapi = dbapi
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if paramstyle is not None:
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self.paramstyle = paramstyle
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elif self.dbapi is not None:
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self.paramstyle = self.dbapi.paramstyle
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else:
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self.paramstyle = self.default_paramstyle
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self.positional = self.paramstyle in ('qmark', 'format', 'numeric')
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self.identifier_preparer = self.preparer(self)
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def create_execution_context(self, connection, **kwargs):
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return DefaultExecutionContext(self, connection, **kwargs)
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def type_descriptor(self, typeobj):
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"""Provide a database-specific ``TypeEngine`` object, given
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the generic object which comes from the types module.
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Subclasses will usually use the ``adapt_type()`` method in the
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types module to make this job easy."""
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if type(typeobj) is type:
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typeobj = typeobj()
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return typeobj
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def validate_identifier(self, ident):
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if len(ident) > self.max_identifier_length:
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raise exc.IdentifierError("Identifier '%s' exceeds maximum length of %d characters" % (ident, self.max_identifier_length))
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def do_begin(self, connection):
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"""Implementations might want to put logic here for turning
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autocommit on/off, etc.
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"""
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pass
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def do_rollback(self, connection):
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"""Implementations might want to put logic here for turning
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autocommit on/off, etc.
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"""
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connection.rollback()
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def do_commit(self, connection):
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"""Implementations might want to put logic here for turning
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autocommit on/off, etc.
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"""
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connection.commit()
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def create_xid(self):
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"""Create a random two-phase transaction ID.
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This id will be passed to do_begin_twophase(), do_rollback_twophase(),
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do_commit_twophase(). Its format is unspecified."""
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return "_sa_%032x" % random.randint(0, 2 ** 128)
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def do_savepoint(self, connection, name):
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connection.execute(expression.SavepointClause(name))
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def do_rollback_to_savepoint(self, connection, name):
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connection.execute(expression.RollbackToSavepointClause(name))
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def do_release_savepoint(self, connection, name):
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connection.execute(expression.ReleaseSavepointClause(name))
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def do_executemany(self, cursor, statement, parameters, context=None):
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cursor.executemany(statement, parameters)
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def do_execute(self, cursor, statement, parameters, context=None):
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cursor.execute(statement, parameters)
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def is_disconnect(self, e):
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return False
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class DefaultExecutionContext(base.ExecutionContext):
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def __init__(self, dialect, connection, compiled=None, statement=None, parameters=None):
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self.dialect = dialect
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self._connection = self.root_connection = connection
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self.compiled = compiled
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self.engine = connection.engine
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if compiled is not None:
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# compiled clauseelement. process bind params, process table defaults,
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# track collections used by ResultProxy to target and process results
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self.processors = dict(
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(key, value) for key, value in
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( (compiled.bind_names[bindparam],
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bindparam.bind_processor(self.dialect))
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for bindparam in compiled.bind_names )
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if value is not None)
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self.result_map = compiled.result_map
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if not dialect.supports_unicode_statements:
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self.statement = unicode(compiled).encode(self.dialect.encoding)
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else:
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self.statement = unicode(compiled)
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self.isinsert = compiled.isinsert
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self.isupdate = compiled.isupdate
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if isinstance(compiled.statement, expression._TextClause):
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self.should_autocommit = compiled.statement._autocommit or self.should_autocommit_text(self.statement)
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else:
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self.should_autocommit = getattr(compiled.statement, '_autocommit', False) or self.should_autocommit_compiled(compiled)
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if not parameters:
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self.compiled_parameters = [compiled.construct_params()]
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self.executemany = False
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else:
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self.compiled_parameters = [compiled.construct_params(m) for m in parameters]
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self.executemany = len(parameters) > 1
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self.cursor = self.create_cursor()
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if self.isinsert or self.isupdate:
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self.__process_defaults()
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self.parameters = self.__convert_compiled_params(self.compiled_parameters)
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elif statement is not None:
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# plain text statement.
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self.result_map = None
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self.parameters = self.__encode_param_keys(parameters)
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self.executemany = len(parameters) > 1
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if isinstance(statement, unicode) and not dialect.supports_unicode_statements:
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self.statement = statement.encode(self.dialect.encoding)
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else:
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self.statement = statement
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self.isinsert = self.isupdate = False
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self.cursor = self.create_cursor()
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self.should_autocommit = self.should_autocommit_text(statement)
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else:
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# no statement. used for standalone ColumnDefault execution.
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self.statement = None
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self.isinsert = self.isupdate = self.executemany = self.should_autocommit = False
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self.cursor = self.create_cursor()
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@property
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def connection(self):
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return self._connection._branch()
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def __encode_param_keys(self, params):
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"""apply string encoding to the keys of dictionary-based bind parameters.
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This is only used executing textual, non-compiled SQL expressions."""
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if self.dialect.positional or self.dialect.supports_unicode_statements:
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if params:
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return params
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elif self.dialect.positional:
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return [()]
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else:
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return [{}]
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else:
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def proc(d):
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# sigh, sometimes we get positional arguments with a dialect
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# that doesnt specify positional (because of execute_text())
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if not isinstance(d, dict):
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return d
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return dict((k.encode(self.dialect.encoding), d[k]) for k in d)
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return [proc(d) for d in params] or [{}]
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def __convert_compiled_params(self, compiled_parameters):
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"""convert the dictionary of bind parameter values into a dict or list
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to be sent to the DBAPI's execute() or executemany() method.
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"""
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processors = self.processors
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parameters = []
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if self.dialect.positional:
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for compiled_params in compiled_parameters:
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param = []
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for key in self.compiled.positiontup:
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if key in processors:
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param.append(processors[key](compiled_params[key]))
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else:
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param.append(compiled_params[key])
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parameters.append(param)
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else:
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encode = not self.dialect.supports_unicode_statements
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for compiled_params in compiled_parameters:
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param = {}
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if encode:
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encoding = self.dialect.encoding
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for key in compiled_params:
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if key in processors:
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param[key.encode(encoding)] = processors[key](compiled_params[key])
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else:
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param[key.encode(encoding)] = compiled_params[key]
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else:
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for key in compiled_params:
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if key in processors:
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param[key] = processors[key](compiled_params[key])
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else:
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param[key] = compiled_params[key]
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parameters.append(param)
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return parameters
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def should_autocommit_compiled(self, compiled):
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return isinstance(compiled.statement, expression._UpdateBase)
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def should_autocommit_text(self, statement):
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return AUTOCOMMIT_REGEXP.match(statement)
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def create_cursor(self):
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return self._connection.connection.cursor()
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def pre_execution(self):
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self.pre_exec()
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def post_execution(self):
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self.post_exec()
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def pre_exec(self):
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pass
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def post_exec(self):
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pass
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def get_result_proxy(self):
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return base.ResultProxy(self)
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def get_rowcount(self):
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if hasattr(self, '_rowcount'):
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return self._rowcount
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else:
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return self.cursor.rowcount
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def supports_sane_rowcount(self):
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return self.dialect.supports_sane_rowcount
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def supports_sane_multi_rowcount(self):
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return self.dialect.supports_sane_multi_rowcount
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def last_inserted_ids(self):
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return self._last_inserted_ids
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def last_inserted_params(self):
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return self._last_inserted_params
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def last_updated_params(self):
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return self._last_updated_params
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def lastrow_has_defaults(self):
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return hasattr(self, 'postfetch_cols') and len(self.postfetch_cols)
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def set_input_sizes(self):
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"""Given a cursor and ClauseParameters, call the appropriate
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style of ``setinputsizes()`` on the cursor, using DB-API types
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from the bind parameter's ``TypeEngine`` objects.
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"""
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types = dict(
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(self.compiled.bind_names[bindparam], bindparam.type)
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for bindparam in self.compiled.bind_names)
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if self.dialect.positional:
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inputsizes = []
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for key in self.compiled.positiontup:
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typeengine = types[key]
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dbtype = typeengine.dialect_impl(self.dialect).get_dbapi_type(self.dialect.dbapi)
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if dbtype is not None:
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inputsizes.append(dbtype)
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try:
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self.cursor.setinputsizes(*inputsizes)
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except Exception, e:
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self._connection._handle_dbapi_exception(e, None, None, None)
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raise
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else:
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inputsizes = {}
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for key in self.compiled.bind_names.values():
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typeengine = types[key]
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dbtype = typeengine.dialect_impl(self.dialect).get_dbapi_type(self.dialect.dbapi)
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if dbtype is not None:
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inputsizes[key.encode(self.dialect.encoding)] = dbtype
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try:
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self.cursor.setinputsizes(**inputsizes)
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except Exception, e:
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self._connection._handle_dbapi_exception(e, None, None, None)
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raise
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def __process_defaults(self):
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"""generate default values for compiled insert/update statements,
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and generate last_inserted_ids() collection."""
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if self.executemany:
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if len(self.compiled.prefetch):
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drunner = self.dialect.defaultrunner(self)
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params = self.compiled_parameters
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for param in params:
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# assign each dict of params to self.compiled_parameters;
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# this allows user-defined default generators to access the full
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# set of bind params for the row
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self.compiled_parameters = param
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for c in self.compiled.prefetch:
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if self.isinsert:
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val = drunner.get_column_default(c)
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else:
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val = drunner.get_column_onupdate(c)
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if val is not None:
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param[c.key] = val
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self.compiled_parameters = params
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else:
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compiled_parameters = self.compiled_parameters[0]
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drunner = self.dialect.defaultrunner(self)
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for c in self.compiled.prefetch:
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if self.isinsert:
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val = drunner.get_column_default(c)
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else:
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val = drunner.get_column_onupdate(c)
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if val is not None:
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compiled_parameters[c.key] = val
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if self.isinsert:
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self._last_inserted_ids = [compiled_parameters.get(c.key, None) for c in self.compiled.statement.table.primary_key]
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self._last_inserted_params = compiled_parameters
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else:
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self._last_updated_params = compiled_parameters
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self.postfetch_cols = self.compiled.postfetch
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self.prefetch_cols = self.compiled.prefetch
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