Make ReturnDict cachable. Closes #2360.

rest_framework/utils/serializer_helpers.py

@@ -19,6 +19,11 @@ class ReturnDict(OrderedDict):
     def __repr__(self):
         return dict.__repr__(self)
 
+    def __reduce__(self):
+        # Pickling these objects will drop the .serializer backlink,
+        # but preserve the raw data.
+        return (dict, (dict(self),))
+
 
 class ReturnList(list):
     """
@@ -33,6 +38,11 @@ class ReturnList(list):
     def __repr__(self):
         return list.__repr__(self)
 
+    def __reduce__(self):
+        # Pickling these objects will drop the .serializer backlink,
+        # but preserve the raw data.
+        return (list, (list(self),))
+
 
 class BoundField(object):
     """

tests/test_serializer.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 from .utils import MockObject
 from rest_framework import serializers
 from rest_framework.compat import unicode_repr
+import pickle
 import pytest
 
 
@@ -278,3 +279,19 @@ class TestNotRequiredOutput:
         serializer = ExampleSerializer(instance)
         with pytest.raises(AttributeError):
             serializer.data
+
+
+class TestCacheSerializerData:
+    def test_cache_serializer_data(self):
+        """
+        Caching serializer data with pickle will drop the serializer info,
+        but does preserve the data itself.
+        """
+        class ExampleSerializer(serializers.Serializer):
+            field1 = serializers.CharField()
+            field2 = serializers.CharField()
+
+        serializer = ExampleSerializer({'field1': 'a', 'field2': 'b'})
+        pickled = pickle.dumps(serializer.data)
+        data = pickle.loads(pickled)
+        assert data == {'field1': 'a', 'field2': 'b'}