Merge pull request #739 from craigds/basic-nested-serialization

tweaks to writable nested serializers

rest_framework/serializers.py

@@ -129,8 +129,8 @@ class BaseSerializer(WritableField):
     _dict_class = SortedDictWithMetadata
 
     def __init__(self, instance=None, data=None, files=None,
-                 context=None, partial=False, many=None, source=None):
-        super(BaseSerializer, self).__init__(source=source)
+                 context=None, partial=False, many=None, **kwargs):
+        super(BaseSerializer, self).__init__(**kwargs)
         self.opts = self._options_class(self.Meta)
         self.parent = None
         self.root = None
@@ -358,6 +358,10 @@ class BaseSerializer(WritableField):
         try:
             value = data[field_name]
         except KeyError:
+            if self.default is not None and not self.partial:
+                # Note: partial updates shouldn't set defaults
+                value = copy.deepcopy(self.default)
+            else:
                 if self.required:
                     raise ValidationError(self.error_messages['required'])
                 return