  class ManyRelatedMixin(object):
      """
      Mixin to convert a related field to a many related field.
      """
      def field_to_native(self, obj, field_name):
          value = getattr(obj, self.source or field_name)
          return [self.to_native(item) for item in value.all()]
  
      def field_from_native(self, data, field_name, into):
 
</s> remove     Serializes a to-many related field or related manager to a pk value.
 </s> add     Represents a to-many relationship as a pk value. </s> remove     Serializes a related field or related object to a pk value.
 </s> add     Represents a to-one relationship as a pk value. </s> remove         # TODO: Make this mandatory, and have the HyperlinkedModelSerializer
        # set it on-the-fly
 </s> add         # TODO: Make view_name mandatory, and have the
        # HyperlinkedModelSerializer set it on-the-fly </s> remove     A field that represents the model's identity using a hyperlink.
 </s> add     Represents the instance, or a property on the instance, using hyperlinking.
    widget = widgets.SelectMultiple

  class ManyRelatedMixin(object):
      """
      Mixin to convert a related field to a many related field.
      """
    widget = widgets.SelectMultiple

      def field_to_native(self, obj, field_name):
          value = getattr(obj, self.source or field_name)
          return [self.to_native(item) for item in value.all()]
  
      def field_from_native(self, data, field_name, into):
keep keep keep add keep keep keep keep keep
 Relational field support in browseable API.

Add slug relational fields.
Add quickstart. 
rest_framework/fields.py