Author: jpellerin
Date: 2006-07-19 13:56:31 -0500 (Wed, 19 Jul 2006)
New Revision: 3385
Modified:
django/branches/multiple-db-support/django/db/__init__.py
Log:
[multi-db] Moved ConnectionInfoDescriptor() from manager to django.db,
added model_connection_name() function in django.db.
Modified: django/branches/multiple-db-support/django/db/__init__.py
===================================================================
--- django/branches/multiple-db-support/django/db/__init__.py 2006-07-19
18:10:19 UTC (rev 3384)
+++ django/branches/multiple-db-support/django/db/__init__.py 2006-07-19
18:56:31 UTC (rev 3385)
@@ -236,7 +236,81 @@
def close(self):
self.local.db = None
+
+def model_connection_name(klass):
+ """Get the connection name that a model is configured to use, with the
+ given settings.
+ """
+ app = klass._meta.app_label
+ model = klass.__name__
+ app_model = "%s.%s" % (app, model)
+
+ # Quick exit if no OTHER_DATABASES defined
+ if (not hasattr(settings, 'OTHER_DATABASES')
+ or not settings.OTHER_DATABASES):
+ return _default
+ # Look in MODELS for the best match: app_label.Model. If that isn't
+ # found, take just app_label. If nothing is found, use the default
+ maybe = None
+ for name, db_def in settings.OTHER_DATABASES.items():
+ if not 'MODELS' in db_def:
+ continue
+ mods = db_def['MODELS']
+ # Can't get a better match than this
+ if app_model in mods:
+ return name
+ elif app in mods:
+ if maybe is not None:
+ raise ImproperlyConfigured, \
+ "App %s appears in more than one OTHER_DATABASES " \
+ "setting (%s and %s)" % (maybe, name)
+ maybe = name
+ if maybe:
+ return maybe
+ # No named connection for this model; use the default
+ return _default
+
+class ConnectionInfoDescriptor(object):
+ """Descriptor used to access database connection information from a
+ manager or other connection holder. Keeps a thread-local cache of
+ connections per instance, and always returns the same connection for an
+ instance in particular thread during a particular request.
+
+ Any object that includes an attribute ``model`` that holds a model class
+ can use this descriptor to manage connections.
+ """
+
+ def __init__(self):
+ self.cnx = local()
+ self.cnx.cache = {}
+ def __get__(self, instance, type=None):
+ if instance is None:
+ raise AttributeError, \
+ "ConnectionInfo is accessible only through an instance"
+ instance_connection = self.cnx.cache.get(instance, None)
+ if instance_connection is None:
+ instance_connection = self.get_connection(instance)
+ def reset():
+ self.reset(instance)
+ dispatcher.connect(reset, signal=signals.request_finished)
+ self.cnx.cache[instance] = instance_connection
+ return instance_connection
+
+ def __set__(self, instance, value):
+ self.cnx.cache[instance] = instance_connection
+
+ def __delete__(self, instance):
+ self.reset(instance)
+
+ def get_connection(self, instance):
+ return connections[model_connection_name(instance.model)]
+
+ def reset(self, instance):
+ self.cnx.cache[instance] = None
+
+
+
# Backwards compatibility: establish the default connection and set the
# default connection properties at module level
connection_info = DefaultConnectionInfoProxy()
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