From 4f461542b59d4ba6c366eab08bde783f68977ce0 Mon Sep 17 00:00:00 2001
From: Alex Gaynor <alex.gaynor@gmail.com>
Date: Thu, 18 Jun 2009 17:31:36 +0000
Subject: [PATCH] [soc2009/multidb] Ensure that when a QuerySet is given a
 Query object in its construct that we correct the detect the connection that
 is being used

git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2009/multidb@11073 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/db/models/query.py                        |  3 +--
 django/db/utils.py                               | 10 ++++++++++
 tests/regressiontests/multiple_database/tests.py |  7 ++++++-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/django/db/models/query.py b/django/db/models/query.py
index 89768ef023..c6071281b5 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -38,8 +38,7 @@ class QuerySet(object):
         self._result_cache = None
         self._iter = None
         self._sticky_filter = False
-        self._using = DEFAULT_DB_ALIAS # this will be wrong if a custom Query
-                                       # is provided with a non default connection
+        self._using = connections.alias_for_connection(self.query.connection)
 
     ########################
     # PYTHON MAGIC METHODS #
diff --git a/django/db/utils.py b/django/db/utils.py
index 0b51648384..553bbca48d 100644
--- a/django/db/utils.py
+++ b/django/db/utils.py
@@ -68,3 +68,13 @@ class ConnectionHandler(object):
 
     def all(self):
         return [self[alias] for alias in self]
+
+    def alias_for_connection(self, connection):
+        """
+        Returns the alias for the given connection object.
+        """
+        for alias in self:
+            conn_settings = self.databases[alias]
+            if conn_settings == connection.settings_dict:
+                return alias
+        return None
diff --git a/tests/regressiontests/multiple_database/tests.py b/tests/regressiontests/multiple_database/tests.py
index b7ca0e5e23..f38ddda490 100644
--- a/tests/regressiontests/multiple_database/tests.py
+++ b/tests/regressiontests/multiple_database/tests.py
@@ -6,7 +6,7 @@ from django.test import TestCase
 
 from models import Book
 
-class DatabaseSettingTestCase(TestCase):
+class ConnectionHandlerTestCase(TestCase):
     def setUp(self):
         settings.DATABASES['__test_db'] = {
             'DATABASE_ENGINE': 'sqlite3',
@@ -20,6 +20,11 @@ class DatabaseSettingTestCase(TestCase):
         connections['default'].cursor()
         connections['__test_db'].cursor()
 
+    def test_alias_for_connection(self):
+        for db in connections:
+            self.assertEqual(db, connections.alias_for_connection(connections[db]))
+
+
 class QueryTestCase(TestCase):
     def test_basic_queries(self):
         for db in connections: