Fixed #16809 -- Forced MySQL to behave like a database. This avoids a problem where queries that do IS NONE checks can return the wrong result the first time they are executed if there is a recently inserted row. Thanks to James Pyrich for the debug work and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16785 bcc190cf-cafb-0310-a4f2-bffc1f526a37

1 files changed, 10 insertions, 2 deletions

diff --git a/django/db/backends/mysql/base.py b/django/db/backends/mysql/base.py
index a22951a3b7..e9f5b8b6a9 100644
--- a/django/db/backends/mysql/base.py
+++ b/django/db/backends/mysql/base.py
@@ -309,7 +309,9 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         return False
 
     def _cursor(self):
+        new_connection = False
         if not self._valid_connection():
+            new_connection = True
             kwargs = {
                 'conv': django_conversions,
                 'charset': 'utf8',
@@ -336,8 +338,14 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             self.connection.encoders[SafeUnicode] = self.connection.encoders[unicode]
             self.connection.encoders[SafeString] = self.connection.encoders[str]
             connection_created.send(sender=self.__class__, connection=self)
-        cursor = CursorWrapper(self.connection.cursor())
-        return cursor
+        cursor = self.connection.cursor()
+        if new_connection:
+            # SQL_AUTO_IS_NULL in MySQL controls whether an AUTO_INCREMENT column
+            # on a recently-inserted row will return when the field is tested for
+            # NULL.  Disabling this value brings this aspect of MySQL in line with
+            # SQL standards.
+            cursor.execute('SET SQL_AUTO_IS_NULL = 0')
+        return CursorWrapper(cursor)
 
     def _rollback(self):
         try: