def get_object(self, request, object_id):
        """
        Returns an instance matching the primary key provided. ``None``  is
        returned if no match is found (or the object_id failed validation
        against the primary key field).
        """
        queryset = self.queryset(request)
        model = queryset.model
        try:
            object_id = model._meta.pk.to_python(object_id)
            return queryset.get(pk=object_id)
        except (model.DoesNotExist, ValidationError):
            return None