django1/django/db/__init__.py

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import warnings
from django.conf import settings
from django.core import signals
from django.core.exceptions import ImproperlyConfigured
Refactored database exceptions wrapping. Squashed commit of the following: commit 2181d833ed1a2e422494738dcef311164c4e097e Author: Aymeric Augustin <aymeric.augustin@m4x.org> Date: Wed Feb 27 14:28:39 2013 +0100 Fixed #15901 -- Wrapped all PEP-249 exceptions. commit 5476a5d93c19aa2f928c497d39ce6e33f52694e2 Author: Aymeric Augustin <aymeric.augustin@m4x.org> Date: Tue Feb 26 17:26:52 2013 +0100 Added PEP 3134 exception chaining. Thanks Jacob Kaplan-Moss for the suggestion. commit 9365fad0a650328002fb424457d675a273c95802 Author: Aymeric Augustin <aymeric.augustin@m4x.org> Date: Tue Feb 26 17:13:49 2013 +0100 Improved API for wrapping database errors. Thanks Alex Gaynor for the proposal. commit 1b463b765f2826f73a8d9266795cd5da4f8d5e9e Author: Aymeric Augustin <aymeric.augustin@m4x.org> Date: Tue Feb 26 15:00:39 2013 +0100 Removed redundant exception wrapping. This is now taken care of by the cursor wrapper. commit 524bc7345a724bf526bdd2dd1bcf5ede67d6bb5c Author: Aymeric Augustin <aymeric.augustin@m4x.org> Date: Tue Feb 26 14:55:10 2013 +0100 Wrapped database exceptions in the base backend. This covers the most common PEP-249 APIs: - Connection APIs: close(), commit(), rollback(), cursor() - Cursor APIs: callproc(), close(), execute(), executemany(), fetchone(), fetchmany(), fetchall(), nextset(). Fixed #19920. commit a66746bb5f0839f35543222787fce3b6a0d0a3ea Author: Aymeric Augustin <aymeric.augustin@m4x.org> Date: Tue Feb 26 14:53:34 2013 +0100 Added a wrap_database_exception context manager and decorator. It re-throws backend-specific exceptions using Django's common wrappers.
2013-02-26 21:53:34 +08:00
from django.db.utils import (DEFAULT_DB_ALIAS,
DataError, OperationalError, IntegrityError, InternalError,
ProgrammingError, NotSupportedError, DatabaseError,
InterfaceError, Error,
load_backend, ConnectionHandler, ConnectionRouter)
__all__ = ('backend', 'connection', 'connections', 'router', 'DatabaseError',
'IntegrityError', 'DEFAULT_DB_ALIAS')
if settings.DATABASES and DEFAULT_DB_ALIAS not in settings.DATABASES:
raise ImproperlyConfigured("You must define a '%s' database" % DEFAULT_DB_ALIAS)
connections = ConnectionHandler(settings.DATABASES)
router = ConnectionRouter(settings.DATABASE_ROUTERS)
# `connection`, `DatabaseError` and `IntegrityError` are convenient aliases
# for backend bits.
# DatabaseWrapper.__init__() takes a dictionary, not a settings module, so
# we manually create the dictionary from the settings, passing only the
# settings that the database backends care about. Note that TIME_ZONE is used
# by the PostgreSQL backends.
# We load all these up for backwards compatibility, you should use
# connections['default'] instead.
class DefaultConnectionProxy(object):
"""
Proxy for accessing the default DatabaseWrapper object's attributes. If you
need to access the DatabaseWrapper object itself, use
connections[DEFAULT_DB_ALIAS] instead.
"""
def __getattr__(self, item):
return getattr(connections[DEFAULT_DB_ALIAS], item)
def __setattr__(self, name, value):
return setattr(connections[DEFAULT_DB_ALIAS], name, value)
2013-03-01 00:05:25 +08:00
def __delattr__(self, name):
return delattr(connections[DEFAULT_DB_ALIAS], name)
connection = DefaultConnectionProxy()
backend = load_backend(connection.settings_dict['ENGINE'])
def close_connection(**kwargs):
warnings.warn(
"close_connection is superseded by close_old_connections.",
PendingDeprecationWarning, stacklevel=2)
# Avoid circular imports
from django.db import transaction
for conn in connections:
# If an error happens here the connection will be left in broken
# state. Once a good db connection is again available, the
# connection state will be cleaned up.
transaction.abort(conn)
connections[conn].close()
# Register an event to reset saved queries when a Django request is started.
def reset_queries(**kwargs):
for conn in connections.all():
conn.queries = []
signals.request_started.connect(reset_queries)
# Register an event to reset transaction state and close connections past
# their lifetime. NB: abort() doesn't do anything outside of a transaction.
def close_old_connections(**kwargs):
for conn in connections.all():
try:
conn.abort()
except DatabaseError:
pass
conn.close_if_unusable_or_obsolete()
signals.request_started.connect(close_old_connections)
signals.request_finished.connect(close_old_connections)
# Register an event that rolls back the connections
# when a Django request has an exception.
def _rollback_on_exception(**kwargs):
from django.db import transaction
for conn in connections:
try:
transaction.rollback_unless_managed(using=conn)
except DatabaseError:
pass
signals.got_request_exception.connect(_rollback_on_exception)