Author: jpellerin
Date: 2006-07-18 21:28:24 -0500 (Tue, 18 Jul 2006)
New Revision: 3361
Modified:
django/branches/multiple-db-support/django/db/models/manager.py
Log:
[multi-db] Added ConnectionInfoDescriptor and attached it as db attribute in
Manager class.
Modified: django/branches/multiple-db-support/django/db/models/manager.py
===================================================================
--- django/branches/multiple-db-support/django/db/models/manager.py
2006-07-19 02:09:26 UTC (rev 3360)
+++ django/branches/multiple-db-support/django/db/models/manager.py
2006-07-19 02:28:24 UTC (rev 3361)
@@ -1,11 +1,20 @@
+from django import core
from django.utils.functional import curry
-from django.db import backend, connection
+from django.core.exceptions import ImproperlyConfigured
+from django.db import connections, _default
from django.db.models.query import QuerySet
from django.dispatch import dispatcher
from django.db.models import signals, get_apps, get_models
from django.db.models.fields import FieldDoesNotExist
from django.utils.datastructures import SortedDict
+try:
+ # Only exists in Python 2.4+
+ from threading import local
+except ImportError:
+ # Import copy of _thread_local.py from Python 2.4
+ from django.utils._threading_local import local
+
# Size of each "chunk" for get_iterator calls.
# Larger values are slightly faster at the expense of more storage space.
GET_ITERATOR_CHUNK_SIZE = 100
@@ -25,10 +34,79 @@
cls.add_to_class('objects', Manager())
dispatcher.connect(ensure_default_manager, signal=signals.class_prepared)
+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=core.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):
+ from django.conf import settings
+ app = instance.model._meta.app_label
+ model = instance.model.__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 connections[_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 connections[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 connections[name]
+ # No named connection for this model; use the default
+ return connections[_default]
+
+ def reset(self, instance):
+ self.cnx.cache[instance] = None
+
+
class Manager(object):
# Tracks each time a Manager instance is created. Used to retain order.
creation_counter = 0
-
+ db = ConnectionInfoDescriptor()
+
def __init__(self):
super(Manager, self).__init__()
# Increase the creation counter, and save our local copy.
@@ -44,7 +122,7 @@
or self.creation_counter < model._default_manager.creation_counter
\
or model._default_manager.model != model:
model._default_manager = self
-
+
#######################
# PROXIES TO QUERYSET #
#######################
@@ -119,8 +197,7 @@
such as foreign key constraints for tables that don't exist at
install time.)
"""
- creator = self.model._meta.connection_info.get_creation_module()
- builder = creator.builder
+ builder = self.db.get_creation_module().builder
run, pending = builder.get_create_table(self.model)
run += builder.get_create_indexes(self.model)
if initial_data:
@@ -158,9 +235,8 @@
def get_table_list(self):
"""Get list of tables accessible via my model's connection.
"""
- info = self.model._meta.connection_info
- builder = info.get_creation_module.builder()
- return builder.get_table_list(info)
+ builder = self.db.get_creation_module().builder
+ return builder.get_table_list(self.db)
class ManagerDescriptor(object):
# This class ensures managers aren't accessible via model instances.
@@ -172,3 +248,4 @@
if instance != None:
raise AttributeError, "Manager isn't accessible via %s instances"
% type.__name__
return self.manager
+
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/django-updates
-~----------~----~----~----~------~----~------~--~---
