          super(HyperlinkedRelatedField, self).__init__(*args, **kwargs)
  
      def get_slug_field(self):
          """
          Get the name of a slug field to be used to look up by slug.
          """
          return self.slug_field
  
      def to_native(self, obj):
          view_name = self.view_name
          request = self.context.get('request', None)
          format = self.format or self.context.get('format', None)
  
          if request is None:
              warnings.warn("Using `HyperlinkedRelatedField` without including the "
                            "request in the serializer context is deprecated. "
                            "Add `context={'request': request}` when instantiating the serializer.",
                            DeprecationWarning, stacklevel=4)
  
          pk = getattr(obj, 'pk', None)
          if pk is None:
              return
          kwargs = {self.pk_url_kwarg: pk}
 
</s> remove         kwargs = {self.pk_url_kwarg: obj.pk, self.slug_url_kwarg: slug}
 </s> add         Takes the matched URL conf arguments, and the queryset, and should
        return an object instance, or raise an `ObjectDoesNotExist` exception.
        """
        lookup = view_kwargs.get(self.lookup_field, None)
        pk = view_kwargs.get(self.pk_url_kwarg, None)
        slug = view_kwargs.get(self.slug_url_kwarg, None)

        if lookup is not None:
            filter_kwargs = {self.lookup_field: lookup}
        elif pk is not None:
            filter_kwargs = {'pk': pk}
        elif slug is not None:
            filter_kwargs = {self.slug_field: slug}
        else:
            raise ObjectDoesNotExist()

        return queryset.get(**filter_kwargs)

    def to_native(self, obj):
        view_name = self.view_name
        request = self.context.get('request', None)
        format = self.format or self.context.get('format', None)

        if request is None:
            msg = (
                "Using `HyperlinkedRelatedField` without including the request "
                "in the serializer context is deprecated. "
                "Add `context={'request': request}` when instantiating "
                "the serializer."
            )
            warnings.warn(msg, DeprecationWarning, stacklevel=4)

        # If the object has not yet been saved then we cannot hyperlink to it.
        if getattr(obj, 'pk', None) is None:
            return

        # Return the hyperlink, or error if incorrectly configured. </s> remove         pk = getattr(obj, 'pk', None)
        if pk is None:
            return
        kwargs = {self.pk_url_kwarg: pk}
 </s> add         May raise a `NoReverseMatch` if the `view_name` and `lookup_field`
        attributes are not configured to correctly match the URL conf.
        """
        lookup_field = getattr(obj, self.lookup_field)
        kwargs = {self.lookup_field: lookup_field} </s> remove     def get_slug_field(self):
 </s> add     def get_url(self, obj, view_name, request, format): </s> remove         self.format = kwargs.pop('format', None)
 </s> add  </s> remove         pk = match.kwargs.get(self.pk_url_kwarg, None)
        slug = match.kwargs.get(self.slug_url_kwarg, None)

        # Try explicit primary key.
        if pk is not None:
            queryset = self.queryset.filter(pk=pk)
        # Next, try looking up by slug.
        elif slug is not None:
            slug_field = self.get_slug_field()
            queryset = self.queryset.filter(**{slug_field: slug})
        # If none of those are defined, it's probably a configuation error.
        else:
            raise ValidationError(self.error_messages['configuration_error'])

 </s> add 
        Given an object, return the URL that hyperlinks to the object.
          super(HyperlinkedRelatedField, self).__init__(*args, **kwargs)
  
      def get_slug_field(self):
          """
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
        Given an object, return the URL that hyperlinks to the object.
  
          pk = getattr(obj, 'pk', None)
          if pk is None:
              return
          kwargs = {self.pk_url_kwarg: pk}
keep keep keep keep replace replace replace replace replace replace replace replace replace replace replace replace replace replace keep keep keep keep keep
 lookup_field on hyperlinked fields, and overriddable hyperlinked fields.  Closes #688 
rest_framework/relations.py