Method join_targets

lib/sqlalchemy/orm/relationships.py:3339–3482

Given a source and destination selectable, create a join between them. This takes into account aliasing the join clause to reference the appropriate corresponding columns in the target objects, as well as the extra child criterion, equivalent column sets, etc

(
        self,
        source_selectable: Optional[FromClause],
        dest_selectable: FromClause,
        aliased: bool,
        single_crit: Optional[ColumnElement[bool]] = None,
        extra_criteria: Tuple[ColumnElement[bool], ...] = (),
    )

            return util.EMPTY_SET

    def join_targets(
        self,
        source_selectable: Optional[FromClause],
        dest_selectable: FromClause,
        aliased: bool,
        single_crit: Optional[ColumnElement[bool]] = None,
        extra_criteria: Tuple[ColumnElement[bool], ...] = (),
    ) -> Tuple[
        ColumnElement[bool],
        Optional[ColumnElement[bool]],
        Optional[FromClause],
        Optional[ClauseAdapter],
        FromClause,
    ]:
        """Given a source and destination selectable, create a
        join between them.

        This takes into account aliasing the join clause
        to reference the appropriate corresponding columns
        in the target objects, as well as the extra child
        criterion, equivalent column sets, etc.

        """
        # place a barrier on the destination such that
        # replacement traversals won't ever dig into it.
        # its internal structure remains fixed
        # regardless of context.
        dest_selectable = _shallow_annotate(
            dest_selectable, {"no_replacement_traverse": True}
        )

        primaryjoin, secondaryjoin, secondary = (
            self.primaryjoin,
            self.secondaryjoin,
            self.secondary,
        )

        # adjust the join condition for single table inheritance,
        # in the case that the join is to a subclass
        # this is analogous to the
        # "_adjust_for_single_table_inheritance()" method in Query.

        if single_crit is not None:
            if secondaryjoin is not None:
                secondaryjoin = secondaryjoin & single_crit
            else:
                primaryjoin = primaryjoin & single_crit

        if extra_criteria:

            def mark_exclude_cols(
                elem: SupportsAnnotations, annotations: _AnnotationDict
            ) -> SupportsAnnotations:
                """note unrelated columns in the "extra criteria" as either
                should be adapted or not adapted, even though they are not
                part of our "local" or "remote" side.

                see #9779 for this case, as well as #11010 for a follow up