Merge branch 'version-3.1' into cursor-pagination

3 files changed, 14 insertions, 3 deletions

diff --git a/rest_framework/compat.py b/rest_framework/compat.py
index bd3802ad..a6620057 100644
--- a/rest_framework/compat.py
+++ b/rest_framework/compat.py
@@ -18,7 +18,7 @@ def unicode_repr(instance):
     # Get the repr of an instance, but ensure it is a unicode string
     # on both python 3 (already the case) and 2 (not the case).
     if six.PY2:
-        repr(instance).decode('utf-8')
+        return repr(instance).decode('utf-8')
     return repr(instance)
 
 
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 77d3f202..b91ecebc 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -253,7 +253,7 @@ class SerializerMetaclass(type):
         # If this class is subclassing another Serializer, add that Serializer's
         # fields.  Note that we loop over the bases in *reverse*. This is necessary
         # in order to maintain the correct order of fields.
-        for base in bases[::-1]:
+        for base in reversed(bases):
             if hasattr(base, '_declared_fields'):
                 fields = list(base._declared_fields.items()) + fields
 
@@ -899,7 +899,15 @@ class ModelSerializer(Serializer):
         if fields is not None:
             # Ensure that all declared fields have also been included in the
             # `Meta.fields` option.
-            for field_name in declared_fields:
+
+            # Do not require any fields that are declared a parent class,
+            # in order to allow serializer subclasses to only include
+            # a subset of fields.
+            required_field_names = set(declared_fields)
+            for cls in self.__class__.__bases__:
+                required_field_names -= set(getattr(cls, '_declared_fields', []))
+
+            for field_name in required_field_names:
                 assert field_name in fields, (
                     "The field '{field_name}' was declared on serializer "
                     "{serializer_class}, but has not been included in the "
diff --git a/rest_framework/utils/serializer_helpers.py b/rest_framework/utils/serializer_helpers.py
index f9960603..ab057862 100644
--- a/rest_framework/utils/serializer_helpers.py
+++ b/rest_framework/utils/serializer_helpers.py
@@ -105,3 +105,6 @@ class BindingDict(collections.MutableMapping):
 
     def __len__(self):
         return len(self.fields)
+
+    def __repr__(self):
+        return dict.__repr__(self.fields)