queryset-refactor: Different database backends return different empty sequences

when fetchmany() is exhausted. This change allows for that. Fixed #6807.

Nice debugging from tpherndon.


git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7283 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/__init__.py

@@ -50,6 +50,7 @@ class BaseDatabaseFeatures(object):
     supports_tablespaces = False
     uses_case_insensitive_names = False
     uses_custom_queryset = False
+    empty_fetchmany_value = []
 
 class BaseDatabaseOperations(object):
     """

django/db/backends/mysql/base.py

@@ -61,6 +61,7 @@ server_version_re = re.compile(r'(\d{1,2})\.(\d{1,2})\.(\d{1,2})')
 class DatabaseFeatures(BaseDatabaseFeatures):
     autoindexes_primary_keys = False
     inline_fk_references = False
+    empty_fetchmany_value = ()
 
 class DatabaseOperations(BaseDatabaseOperations):
     def date_extract_sql(self, lookup_type, field_name):

django/db/backends/mysql_old/base.py

@@ -66,6 +66,7 @@ class MysqlDebugWrapper:
 class DatabaseFeatures(BaseDatabaseFeatures):
     autoindexes_primary_keys = False
     inline_fk_references = False
+    empty_fetchmany_value = ()
 
 class DatabaseOperations(BaseDatabaseOperations):
     def date_extract_sql(self, lookup_type, field_name):

django/db/models/sql/query.py

@@ -1330,7 +1330,8 @@ class Query(object):
         if result_type == SINGLE:
             return cursor.fetchone()
         # The MULTI case.
-        return iter((lambda: cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)), [])
+        return iter((lambda: cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)),
+                self.connection.features.empty_fetchmany_value)
 
 def get_order_dir(field, default='ASC'):
     """