Method visit_column

lib/sqlalchemy/orm/evaluator.py:87–139

(self, clause)

        return lambda obj: True

    def visit_column(self, clause):
        try:
            parentmapper = clause._annotations["parentmapper"]
        except KeyError as ke:
            raise UnevaluatableError(
                f"Cannot evaluate column: {clause}"
            ) from ke

        if self.target_cls and not issubclass(
            self.target_cls, parentmapper.class_
        ):
            raise UnevaluatableError(
                "Can't evaluate criteria against "
                f"alternate class {parentmapper.class_}"
            )

        parentmapper._check_configure()

        # we'd like to use "proxy_key" annotation to get the "key", however
        # in relationship primaryjoin cases proxy_key is sometimes deannotated
        # and sometimes apparently not present in the first place (?).
        # While I can stop it from being deannotated (though need to see if
        # this breaks other things), not sure right now  about cases where it's
        # not there in the first place.  can fix at some later point.
        # key = clause._annotations["proxy_key"]

        # for now, use the old way
        try:
            key = parentmapper._columntoproperty[clause].key
        except orm_exc.UnmappedColumnError as err:
            raise UnevaluatableError(
                f"Cannot evaluate expression: {err}"
            ) from err

        # note this used to fall back to a simple `getattr(obj, key)` evaluator
        # if impl was None; as of #8656, we ensure mappers are configured
        # so that impl is available
        impl = parentmapper.class_manager[key].impl

        def get_corresponding_attr(obj):
            if obj is None:
                return _NO_OBJECT
            state = inspect(obj)
            dict_ = state.dict

            value = impl.get(
                state, dict_, passive=PassiveFlag.PASSIVE_NO_FETCH
            )
            if value is LoaderCallableStatus.PASSIVE_NO_RESULT:
                return _EXPIRED_OBJECT
            return value

        return get_corresponding_attr

    def visit_tuple(self, clause):
        return self.visit_clauselist(clause)