Fix initial data on serializers to reflect writable fields

rest_framework/renderers.py

@@ -581,12 +581,7 @@ class BrowsableAPIRenderer(BaseRenderer):
                 # View has a serializer defined and parser class has a
                 # corresponding renderer that can be used to render the data.
 
-                # Get a read-only version of the serializer
                 serializer = view.get_serializer(instance=instance)
-                if instance is None:
-                    for name, field in serializer.fields.items():
-                        if getattr(field, 'read_only', None):
-                            del serializer.fields[name]
 
                 # Render the raw data content
                 renderer = renderer_class()

rest_framework/serializers.py

@@ -234,12 +234,13 @@ class Serializer(BaseSerializer):
                 (field_name, field.get_value(self._initial_data))
                 for field_name, field in self.fields.items()
                 if field.get_value(self._initial_data) is not empty
+                and not field.read_only
             ], serializer=self)
 
         return ReturnDict([
             (field.field_name, field.get_initial())
             for field in self.fields.values()
-            if not field.write_only
+            if not field.read_only
         ], serializer=self)
 
     def get_value(self, dictionary):