Method select_related

django/db/models/query.py:1756–1786

Return a new QuerySet instance that will select related objects. If fields are specified, they must be ForeignKey fields and only those related objects are included in the selection. If select_related(None) is called, clear the list.

(self, *fields)

        return obj

    def select_related(self, *fields):
        """
        Return a new QuerySet instance that will select related objects.

        If fields are specified, they must be ForeignKey fields and only those
        related objects are included in the selection.

        If select_related(None) is called, clear the list.
        """
        self._not_support_combined_queries("select_related")
        if self._fields is not None:
            raise TypeError(
                "Cannot call select_related() after .values() or .values_list()"
            )

        obj = self._chain()
        if fields == (None,):
            obj.query.select_related = False
        elif fields:
            obj.query.add_select_related(fields)
        else:
            # RemovedInDjango70Warning: when the deprecation ends, raise a
            # TypeError instead.
            warnings.warn(
                "Calling select_related() with no arguments is deprecated. "
                "Specify the fields to fetch instead.",
                category=RemovedInDjango70Warning,
                skip_file_prefixes=django_file_prefixes(),
            )
            obj.query.select_related = True
        return obj

    def prefetch_related(self, *lookups):
        """