mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-18 14:42:01 -04:00
Mike Bayer
2cf8c5868c
Refined the behavior of ORM subquery rendering with regards to deferred columns and column properties to be more compatible with that of 1.3 while also providing for 1.4's newer features. As a subquery in 1.4 does not make use of loader options, including :func:`_orm.deferred`, a subquery that is against an ORM entity with deferred attributes will now render those deferred attributes that refer directly to mapped table columns, as these are needed in the outer SELECT if that outer SELECT makes use of these columns; however a deferred attribute that refers to a composed SQL expression as we normally do with :func:`_orm.column_property` will not be part of the subquery, as these can be selected explicitly if needed in the subquery. If the entity is being SELECTed from this subquery, the column expression can still render on "the outside" in terms of the derived subquery columns. This produces essentially the same behavior as when working with 1.3. However in this case the fix has to also make sure that the ``.selected_columns`` collection of an ORM-enabled :func:`_sql.select` also follows these rules, which in particular allows recursive CTEs to render correctly in this scenario, which were previously failing to render correctly due to this issue. As part of this change the _exported_columns_iterator() method has been removed and logic simplified to use ._all_selected_columns from any SelectBase object where _exported_columns_iterator() was used before. Additionally sets up UpdateBase to include ReturnsRows in its hierarchy; the literal point of ReturnsRows was to be a common base for UpdateBase and SelectBase so it was kind of weird it wasn't there. Fixes: #6661 Fixed issue in CTE constructs mostly relevant to ORM use cases where a recursive CTE against "anonymous" labels such as those seen in ORM ``column_property()`` mappings would render in the ``WITH RECURSIVE xyz(...)`` section as their raw internal label and not a cleanly anonymized name. Fixes: #6663 Change-Id: I26219d4d8e6c0915b641426e9885540f74fae4d2