From a337dc3b5f3816987515ccb3ce31a6801aa46520 Mon Sep 17 00:00:00 2001
From: George Hickman <george@ghickman.co.uk>
Date: Wed, 20 Mar 2013 23:55:13 -0700
Subject: [PATCH] Add IfMatchMissing exception

Needed to make testing easier.
---
 rest_framework/exceptions.py | 8 ++++++++
 rest_framework/views.py      | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/rest_framework/exceptions.py b/rest_framework/exceptions.py
index 9ceb64fe1..229c8df82 100644
--- a/rest_framework/exceptions.py
+++ b/rest_framework/exceptions.py
@@ -96,6 +96,14 @@ class PreconditionFailed(APIException):
         self.detail = detail or self.default_detail
 
 
+class IfMatchMissing(APIException):
+    default_detail = 'IF_MATCH header is required'
+    status_code = 400
+
+    def __init__(self, detail=None):
+        self.detail = detail or self.default_detail
+
+
 class ConfigurationError(Exception):
     """
     Indicates an internal server error.
diff --git a/rest_framework/views.py b/rest_framework/views.py
index 98c7dcc64..36f5a92fa 100644
--- a/rest_framework/views.py
+++ b/rest_framework/views.py
@@ -401,7 +401,7 @@ class APIView(View):
             if getattr(self, 'use_etags', False) and request.method.lower() in ('put', 'delete'):
                 self.etag_header = request.META.get('HTTP_IF_MATCH')
                 if self.etag_header is None:
-                    return Response({'detail': 'IF_MATCH header is required'}, status=400, exception=True)
+                    raise exceptions.IfMatchMissing
 
             response = handler(request, *args, **kwargs)