Fixed #7572 -- Force the closure of the database connection at the end of fixture loading as a workaround for MySQL bug #37735. Thanks to Simon Litchfield for his help in narrowing down this issue.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7803 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management/commands/loaddata.py

@@ -162,3 +162,9 @@ class Command(BaseCommand):
         else:
             if verbosity > 0:
                 print "Installed %d object(s) from %d fixture(s)" % (object_count, fixture_count)
+                
+        # Close the DB connection. This is required as a workaround for an
+        # edge case in MySQL: if the same connection is used to
+        # create tables, load data, and query, the query can return
+        # incorrect results. See Django #7572, MySQL #37735.
+        connection.close()

tests/regressiontests/fixtures_regress/fixtures/big-fixture.json

@@ -0,0 +1,83 @@
+[
+    {
+        "pk": 6,
+        "model": "fixtures_regress.channel",
+        "fields": {
+            "name": "Business"
+        }        
+    },
+    
+    {
+        "pk": 1,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Article Title 1",
+            "channels": [6]
+        }    
+    },
+    {
+        "pk": 2,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Article Title 2",
+            "channels": [6]
+        }    
+    },
+    {
+        "pk": 3,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Article Title 3",
+            "channels": [6]
+        }    
+    },
+    {
+        "pk": 4,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Article Title 4",
+            "channels": [6]
+        }    
+    },
+
+    {
+        "pk": 5,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Article Title 5",
+            "channels": [6]
+        }    
+    },
+    {
+        "pk": 6,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Article Title 6",
+            "channels": [6]
+        }    
+    },
+    {
+        "pk": 7,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Article Title 7",
+            "channels": [6]
+        }    
+    },
+    {
+        "pk": 8,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Article Title 8",
+            "channels": [6]
+        }    
+    },
+    {
+        "pk": 9,
+        "model": "fixtures_regress.article",
+        "fields": {
+            "title": "Yet Another Article",
+            "channels": [6]
+        }    
+    }
+]

tests/regressiontests/fixtures_regress/models.py

@@ -44,6 +44,16 @@ class Parent(models.Model):
 class Child(Parent):
     data = models.CharField(max_length=10)
 
+# Models to regresison check #7572
+class Channel(models.Model):
+    name = models.CharField(max_length=255)
+
+class Article(models.Model):
+    title = models.CharField(max_length=255)
+    channels = models.ManyToManyField(Channel)
+    
+    class Meta:
+        ordering = ('id',)
 
 __test__ = {'API_TESTS':"""
 >>> from django.core import management
@@ -107,4 +117,21 @@ No fixture data found for 'bad_fixture2'. (File format may be invalid.)
 
 >>> management.call_command('loaddata', 'model-inheritance.json', verbosity=0)
 
+###############################################
+# Test for ticket #7572 -- MySQL has a problem if the same connection is 
+# used to create tables, load data, and then query over that data.
+# To compensate, we close the connection after running loaddata.
+# This ensures that a new connection is opened when test queries are issued.
+
+>>> management.call_command('loaddata', 'big-fixture.json', verbosity=0)
+
+>>> articles = Article.objects.exclude(id=9)
+>>> articles.values_list('id', flat=True)
+[1, 2, 3, 4, 5, 6, 7, 8]
+
+# Just for good measure, run the same query again. Under the influence of
+# ticket #7572, this will give a different result to the previous call.
+>>> articles.values_list('id', flat=True)
+[1, 2, 3, 4, 5, 6, 7, 8]
+
 """}