Merge pull request #477 from roberts81/master

Fix for #460 

1 files changed, 10 insertions, 1 deletions

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index e63f4783..67eafdf0 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -22,7 +22,16 @@ class DictWithMetadata(dict):
     """
     A dict-like object, that can have additional properties attached.
     """
-    pass
+    def __getstate__(self):
+        """
+        Used by pickle (e.g., caching).
+        Overriden to remove metadata from the dict, since it shouldn't be pickled
+        and may in some instances be unpickleable.
+        """
+        # return an instance of the first dict in MRO that isn't a DictWithMetadata
+        for base in self.__class__.__mro__:
+            if not isinstance(base, DictWithMetadata) and isinstance(base, dict):
+                return base(self)
 
 
 class SortedDictWithMetadata(SortedDict, DictWithMetadata):