Method _populate_column_collection

lib/sqlalchemy/sql/selectable.py:1378–1399

(
        self,
        columns: WriteableColumnCollection[str, KeyedColumnElement[Any]],
        primary_key: ColumnSet,
        foreign_keys: Set[KeyedColumnElement[Any]],
    )

    @util.preload_module("sqlalchemy.sql.util")
    def _populate_column_collection(
        self,
        columns: WriteableColumnCollection[str, KeyedColumnElement[Any]],
        primary_key: ColumnSet,
        foreign_keys: Set[KeyedColumnElement[Any]],
    ) -> None:
        sqlutil = util.preloaded.sql_util
        _columns: List[KeyedColumnElement[Any]] = [c for c in self.left.c] + [
            c for c in self.right.c
        ]

        primary_key.extend(
            sqlutil.reduce_columns(
                (c for c in _columns if c.primary_key), self.onclause
            )
        )
        columns._populate_separate_keys(
            (col._tq_key_label, col) for col in _columns  # type: ignore
        )
        foreign_keys.update(
            itertools.chain(*[col.foreign_keys for col in _columns])  # type: ignore  # noqa: E501
        )

    def _copy_internals(
        self, clone: _CloneCallableType = _clone, **kw: Any