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# engine/default.py
# Copyright (C) 2005,2006 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
from sqlalchemy import schema, exceptions, util, sql, types
import sqlalchemy.pool
import StringIO, sys, re
import base
"""provides default implementations of the engine interfaces"""
class PoolConnectionProvider(base.ConnectionProvider):
def __init__(self, dialect, url, poolclass=None, pool=None, **kwargs):
(cargs, cparams) = dialect.create_connect_args(url)
if pool is None:
kwargs.setdefault('echo', False)
kwargs.setdefault('use_threadlocal',True)
if poolclass is None:
poolclass = sqlalchemy.pool.QueuePool
dbapi = dialect.dbapi()
if dbapi is None:
raise exceptions.InvalidRequestError("Cant get DBAPI module for dialect '%s'" % dialect)
self._pool = poolclass(lambda: dbapi.connect(*cargs, **cparams), **kwargs)
else:
if isinstance(pool, sqlalchemy.pool.DBProxy):
self._pool = pool.get_pool(*cargs, **cparams)
else:
self._pool = pool
def get_connection(self):
return self._pool.connect()
def dispose(self):
self._pool.dispose()
if hasattr(self, '_dbproxy'):
self._dbproxy.dispose()
class DefaultDialect(base.Dialect):
"""default implementation of Dialect"""
def __init__(self, convert_unicode=False, encoding='utf-8', **kwargs):
self.convert_unicode = convert_unicode
self.supports_autoclose_results = True
self.encoding = encoding
self.positional = False
self.paramstyle = 'named'
self._ischema = None
self._figure_paramstyle()
def create_execution_context(self):
return DefaultExecutionContext(self)
def type_descriptor(self, typeobj):
"""provides a database-specific TypeEngine object, given the generic object
which comes from the types module. Subclasses will usually use the adapt_type()
method in the types module to make this job easy."""
if type(typeobj) is type:
typeobj = typeobj()
return typeobj
def oid_column_name(self):
return None
def supports_sane_rowcount(self):
return True
def do_begin(self, connection):
"""implementations might want to put logic here for turning autocommit on/off,
etc."""
pass
def do_rollback(self, connection):
"""implementations might want to put logic here for turning autocommit on/off,
etc."""
#print "ENGINE ROLLBACK ON ", connection.connection
connection.rollback()
def do_commit(self, connection):
"""implementations might want to put logic here for turning autocommit on/off, etc."""
#print "ENGINE COMMIT ON ", connection.connection
connection.commit()
def do_executemany(self, cursor, statement, parameters, **kwargs):
cursor.executemany(statement, parameters)
def do_execute(self, cursor, statement, parameters, **kwargs):
cursor.execute(statement, parameters)
def defaultrunner(self, engine, proxy):
return base.DefaultRunner(engine, proxy)
def _set_paramstyle(self, style):
self._paramstyle = style
self._figure_paramstyle(style)
paramstyle = property(lambda s:s._paramstyle, _set_paramstyle)
def convert_compiled_params(self, parameters):
executemany = parameters is not None and isinstance(parameters, list)
# the bind params are a CompiledParams object. but all the DBAPI's hate
# that object (or similar). so convert it to a clean
# dictionary/list/tuple of dictionary/tuple of list
if parameters is not None:
if self.positional:
if executemany:
parameters = [p.values() for p in parameters]
else:
parameters = parameters.values()
else:
if executemany:
parameters = [p.get_raw_dict() for p in parameters]
else:
parameters = parameters.get_raw_dict()
return parameters
def _figure_paramstyle(self, paramstyle=None):
db = self.dbapi()
if paramstyle is not None:
self._paramstyle = paramstyle
elif db is not None:
self._paramstyle = db.paramstyle
else:
self._paramstyle = 'named'
if self._paramstyle == 'named':
self.positional=False
elif self._paramstyle == 'pyformat':
self.positional=False
elif self._paramstyle == 'qmark' or self._paramstyle == 'format' or self._paramstyle == 'numeric':
# for positional, use pyformat internally, ANSICompiler will convert
# to appropriate character upon compilation
self.positional = True
else:
raise DBAPIError("Unsupported paramstyle '%s'" % self._paramstyle)
def _get_ischema(self):
# We use a property for ischema so that the accessor
# creation only happens as needed, since otherwise we
# have a circularity problem with the generic
# ansisql.engine()
if self._ischema is None:
import sqlalchemy.databases.information_schema as ischema
self._ischema = ischema.ISchema(self)
return self._ischema
ischema = property(_get_ischema, doc="""returns an ISchema object for this engine, which allows access to information_schema tables (if supported)""")
class DefaultExecutionContext(base.ExecutionContext):
def __init__(self, dialect):
self.dialect = dialect
def pre_exec(self, engine, proxy, compiled, parameters):
self._process_defaults(engine, proxy, compiled, parameters)
def post_exec(self, engine, proxy, compiled, parameters):
pass
def get_rowcount(self, cursor):
if hasattr(self, '_rowcount'):
return self._rowcount
else:
return cursor.rowcount
def supports_sane_rowcount(self):
return self.dialect.supports_sane_rowcount()
def last_inserted_ids(self):
return self._last_inserted_ids
def last_inserted_params(self):
return self._last_inserted_params
def last_updated_params(self):
return self._last_updated_params
def lastrow_has_defaults(self):
return self._lastrow_has_defaults
def _process_defaults(self, engine, proxy, compiled, parameters):
"""INSERT and UPDATE statements, when compiled, may have additional columns added to their
VALUES and SET lists corresponding to column defaults/onupdates that are present on the
Table object (i.e. ColumnDefault, Sequence, PassiveDefault). This method pre-execs those
DefaultGenerator objects that require pre-execution and sets their values within the
parameter list, and flags the thread-local state about
PassiveDefault objects that may require post-fetching the row after it is inserted/updated.
This method relies upon logic within the ANSISQLCompiler in its visit_insert and
visit_update methods that add the appropriate column clauses to the statement when its
being compiled, so that these parameters can be bound to the statement."""
if compiled is None: return
if getattr(compiled, "isinsert", False):
if isinstance(parameters, list):
plist = parameters
else:
plist = [parameters]
drunner = self.dialect.defaultrunner(engine, proxy)
self._lastrow_has_defaults = False
for param in plist:
last_inserted_ids = []
need_lastrowid=False
for c in compiled.statement.table.c:
if not param.has_key(c.name) or param[c.name] is None:
if isinstance(c.default, schema.PassiveDefault):
self._lastrow_has_defaults = True
newid = drunner.get_column_default(c)
if newid is not None:
param[c.name] = newid
if c.primary_key:
last_inserted_ids.append(param[c.name])
elif c.primary_key:
need_lastrowid = True
elif c.primary_key:
last_inserted_ids.append(param[c.name])
if need_lastrowid:
self._last_inserted_ids = None
else:
self._last_inserted_ids = last_inserted_ids
#print "LAST INSERTED PARAMS", param
self._last_inserted_params = param
elif getattr(compiled, 'isupdate', False):
if isinstance(parameters, list):
plist = parameters
else:
plist = [parameters]
drunner = self.dialect.defaultrunner(engine, proxy)
self._lastrow_has_defaults = False
for param in plist:
for c in compiled.statement.table.c:
if c.onupdate is not None and (not param.has_key(c.name) or param[c.name] is None):
value = drunner.get_column_onupdate(c)
if value is not None:
param[c.name] = value
self._last_updated_params = param
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