From 98b5667a06bcf47c8103bc4b1a502e3d00f3c3c6 Mon Sep 17 00:00:00 2001
From: Malcolm Tredinnick <malcolm.tredinnick@gmail.com>
Date: Tue, 18 Mar 2008 06:15:29 +0000
Subject: [PATCH] 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       | 1 +
 django/db/backends/mysql/base.py     | 1 +
 django/db/backends/mysql_old/base.py | 1 +
 django/db/models/sql/query.py        | 3 ++-
 4 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/django/db/backends/__init__.py b/django/db/backends/__init__.py
index 6ba06f083a..fdbd8f7885 100644
--- a/django/db/backends/__init__.py
+++ b/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):
     """
diff --git a/django/db/backends/mysql/base.py b/django/db/backends/mysql/base.py
index c2b2c7ab1c..cfc07d6008 100644
--- a/django/db/backends/mysql/base.py
+++ b/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):
diff --git a/django/db/backends/mysql_old/base.py b/django/db/backends/mysql_old/base.py
index 374e9af1f5..efbfeeafc5 100644
--- a/django/db/backends/mysql_old/base.py
+++ b/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):
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 384ff140a9..771ee55e12 100644
--- a/django/db/models/sql/query.py
+++ b/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'):
     """