properly detect if an upgrade is necessary using Django's DB introspection.

pyweb/mumble/management/__init__.py

@@ -14,7 +14,7 @@
  *  GNU General Public License for more details.
 """
 
-from django.db		import connection, transaction
+from django.db		import connection
 from django.db.models	import signals
 
 from mumble		import models
@@ -22,31 +22,24 @@ from mumble		import models
 from update_schema	import update_schema
 from server_detect	import find_existing_instances
 
+cursor = connection.cursor()
 
-if not transaction.is_managed():
-	managed_before = False
-	transaction.enter_transaction_management(True)
-	transaction.managed(True)
-else:
-	managed_before = True
-
+tablename = models.Mumble._meta.db_table
 
-cursor = connection.cursor()
-try:
-	cursor.execute( "SELECT server_id FROM mumble_mumble;" )
+uptodate  = False
+if tablename in connection.introspection.get_table_list(cursor):
+	fields = connection.introspection.get_table_description(cursor, tablename)
+	for entry in fields:
+		if entry[0] == "server_id":
+			uptodate = True
+			break
+else:
+	# Table doesn't yet exist, so syncdb will create it properly
+	uptodate = True
 
-except cursor.db.connection.Error:
-	# server_id field does not exist -> DB needs to be updated.
-	transaction.rollback()
+if not uptodate:
 	signals.post_syncdb.connect( update_schema, sender=models );
-
 else:
-	transaction.rollback()
 	signals.post_syncdb.connect( find_existing_instances, sender=models );
 
-finally:
-	if not managed_before:
-		transaction.managed(False)
-		transaction.leave_transaction_management()
-