Reviewed: https://review.opendev.org/c/openstack/neutron/+/744512 Committed: https://opendev.org/openstack/neutron/commit/e98a268de4316c4f889925a3da6266e1c70306aa Submitter: "Zuul (22348)" Branch: master
commit e98a268de4316c4f889925a3da6266e1c70306aa Author: Mike Bayer <[email protected]> Date: Mon Aug 3 11:08:19 2020 -0400 Propose replacement of ORM from_self() The from_self() method in SQLAlchemy is currently being considered for removal from the library, with a deprecation phase throughout 1.4 and then removal by SQLAlchemy 2.0. The from_self() method takes an ORM query object, turns it into a subquery, then returns a new query object that will SELECT from that subquery, while transparently altering subsequent criteria added to the query to be stated in terms of the subquery. The current design direction of SQLAlchemy hopes to de-emphasize the "transparently altering criteria" part of the above use case, and to move users towards a more explicit and model of usage where a subquery should be created and used explicitly using the aliased() construct, which is now very mature and can be used in ways that were not available when from_self() was first introduced. On the SQLAlchemy side, from_self() has proven to be one of the most difficult features to maintain and test as it can easily lead to extremely complicated scenarios, and while I am also experimenting with some alternatives that may still retain some of the "automatic translation" features, those features are still proving to add similar internal complexity which is having me lean towards the original plan of removing open-ended "entity translation" features like that of from_self() at least through the start of the 2.0 series. A code search for all of Openstack shows that the two files modified here are the only usages of the from_self() method throughout all of searchable Openstack code. This speaks to the general obscurity of this method, although neutron's Subnet code is actually using this method as intended. The new approach necessarily changes some of the method signatures here so that the explicit "subquery" entity can be passed; code searches again show that these methods are not being called anywhere outside, so the query_filter_service_subnets method becomes the private _query_entity_service_subnets method. References: https://github.com/sqlalchemy/sqlalchemy/issues/5368 Closes-Bug: #2004263 Change-Id: Icec998873221ac8e6a1566a157b2044c1f6cd7f3 ** Changed in: neutron Status: In Progress => Fix Released ** Bug watch added: github.com/sqlalchemy/sqlalchemy/issues #5368 https://github.com/sqlalchemy/sqlalchemy/issues/5368 -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to neutron. https://bugs.launchpad.net/bugs/2004263 Title: [sqlalchemy-20] Remove ORM "from_self" Status in neutron: Fix Released Bug description: The "from_self()" method in SQLAlchemy is deprecated in version 2.0. The from_self() method takes an ORM query object, turns it into a subquery, then returns a new query object that will SELECT from that subquery, while transparently altering subsequent criteria added to the query to be stated in terms of the subquery. The current design direction of SQLAlchemy hopes to de-emphasize the "transparently altering criteria" part of the above use case, and to move users towards a more explicit and model of usage where a subquery should be created and used explicitly using the aliased() construct, which is now very mature and can be used in ways that were not available when from_self() was first introduced. Reference: https://github.com/sqlalchemy/sqlalchemy/issues/5368 To manage notifications about this bug go to: https://bugs.launchpad.net/neutron/+bug/2004263/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
