[1.0.X] Changed the row count value returned from update queries in some cases.

If an update only affected an ancestor model (not the child), we were
returning 0 for the number of rows updated. This could have been
misleading if the value is used to detect an update occuring. So we now
return the rowcount from the first non-trivial query that is executed
(if any). Still a slight compromise, but better than what we had.

Backport of r9966 from trunk (turns out this *is* a bugfix, since the returned
rowcount is used in Model.save(force_update=True)).

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@9969 bcc190cf-cafb-0310-a4f2-bffc1f526a37

1 files changed, 8 insertions, 3 deletions

diff --git a/django/db/models/sql/subqueries.py b/django/db/models/sql/subqueries.py
index 889188ea51..14af34d7c4 100644
--- a/django/db/models/sql/subqueries.py
+++ b/django/db/models/sql/subqueries.py
@@ -111,14 +111,19 @@ class UpdateQuery(Query):
     def execute_sql(self, result_type=None):
         """
         Execute the specified update. Returns the number of rows affected by
-        the primary update query (there could be other updates on related
-        tables, but their rowcounts are not returned).
+        the primary update query. The "primary update query" is the first
+        non-empty query that is executed. Row counts for any subsequent,
+        related queries are not available.
         """
         cursor = super(UpdateQuery, self).execute_sql(result_type)
         rows = cursor and cursor.rowcount or 0
+        is_empty = cursor is None
         del cursor
         for query in self.get_related_updates():
-            query.execute_sql(result_type)
+            aux_rows = query.execute_sql(result_type)
+            if is_empty:
+                rows = aux_rows
+                is_empty = False
         return rows
 
     def as_sql(self):