[multi-db] For all backends: commit only when a connection exists.

git-svn-id: http://code.djangoproject.com/svn/django/branches/multiple-db-support@4127 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/ado_mssql/base.py

@@ -70,7 +70,8 @@ class DatabaseWrapper(object):
         return cursor
 
     def _commit(self):
-        return self.connection.commit()
+        if self.connection:
+            return self.connection.commit()
 
     def _rollback(self):
         if self.connection:

django/db/backends/mysql/base.py

@@ -91,7 +91,8 @@ class DatabaseWrapper(object):
         return cursor
 
     def _commit(self):
-        self.connection.commit()
+        if self.connection:
+            self.connection.commit()
 
     def _rollback(self):
         if self.connection:

django/db/backends/oracle/base.py

@@ -36,7 +36,8 @@ class DatabaseWrapper(object):
         return FormatStylePlaceholderCursor(self.connection)
 
     def _commit(self):
-        self.connection.commit()
+        if self.connection:
+            self.connection.commit()
 
     def _rollback(self):
         if self.connection:

django/db/backends/postgresql/base.py

@@ -43,7 +43,8 @@ class DatabaseWrapper(object):
         return cursor
 
     def _commit(self):
-        return self.connection.commit()
+        if self.connection:
+            return self.connection.commit()
 
     def _rollback(self):
         if self.connection:

django/db/backends/postgresql_psycopg2/base.py

@@ -44,7 +44,8 @@ class DatabaseWrapper(object):
         return cursor
 
     def _commit(self):
-        return self.connection.commit()
+        if self.connection:
+            return self.connection.commit()
 
     def _rollback(self):
         if self.connection:

django/db/backends/sqlite3/base.py

@@ -56,7 +56,8 @@ class DatabaseWrapper(local):
             return cursor
 
     def _commit(self):
-        self.connection.commit()
+        if self.connection:
+            self.connection.commit()
 
     def _rollback(self):
         if self.connection: