Method only

django/db/models/query.py:1950–1969

Essentially, the opposite of defer(). Only the fields passed into this method and that are not already specified as deferred are loaded immediately when the queryset is evaluated.

(self, *fields)

        return clone

    def only(self, *fields):
        """
        Essentially, the opposite of defer(). Only the fields passed into this
        method and that are not already specified as deferred are loaded
        immediately when the queryset is evaluated.
        """
        self._not_support_combined_queries("only")
        if self._fields is not None:
            raise TypeError("Cannot call only() after .values() or .values_list()")
        if fields == (None,):
            # Can only pass None to defer(), not only(), as the rest option.
            # That won't stop people trying to do this, so let's be explicit.
            raise TypeError("Cannot pass None as an argument to only().")
        for field in fields:
            field = field.split(LOOKUP_SEP, 1)[0]
            if field in self.query._filtered_relations:
                raise ValueError("only() is not supported with FilteredRelation.")
        clone = self._chain()
        clone.query.add_immediate_loading(fields)
        return clone

    def using(self, alias):
        """Select which database this QuerySet should execute against."""