Skip to content

add explicit inverse_of to scoped user_levels association#10745

Merged
wjordan merged 1 commit into
stagingfrom
inverse_of_user_levels
Sep 20, 2016
Merged

add explicit inverse_of to scoped user_levels association#10745
wjordan merged 1 commit into
stagingfrom
inverse_of_user_levels

Conversation

@wjordan

@wjordan wjordan commented Sep 20, 2016

Copy link
Copy Markdown
Contributor

Rails ActiveRecord has an optimization-feature called 'inverse associations' (see "Setting Inverses" API documentation), which optimizes query chains such as parent -> child -> parent going between has_many and belongs_to associations e.g., user.user_levels[0].user, by reusing the original ActiveRecord object rather than re-querying the database to recreate it.

Since Rails 4.1, ActiveRecord tries to automatically infer inverse_of relations based on the class names- however, custom scopes (such as -> {order 'id desc'}) cause the automatic inference to be disabled, so they need to be explicitly added in order for this optimization to be applied.

Before:

irb(main):001:0> User.first.user_levels.first.user
  User Load (0.3ms)  SELECT  `users`.* FROM `users` WHERE `users`.`deleted_at` IS NULL ORDER BY `users`.`id` ASC LIMIT 1
  UserLevel Load (0.3ms)  SELECT  `user_levels`.* FROM `user_levels` WHERE `user_levels`.`user_id` = 1 ORDER BY id desc LIMIT 1
  User Load (0.4ms)  SELECT  `users`.* FROM `users` WHERE `users`.`deleted_at` IS NULL AND `users`.`id` = 1 LIMIT 1

After:

irb(main):001:0> User.first.user_levels.first.user
  User Load (0.9ms)  SELECT  `users`.* FROM `users` WHERE `users`.`deleted_at` IS NULL ORDER BY `users`.`id` ASC LIMIT 1
  UserLevel Load (0.9ms)  SELECT  `user_levels`.* FROM `user_levels` WHERE `user_levels`.`user_id` = 1 ORDER BY `user_levels`.`id` ASC LIMIT 1

@wjordan wjordan mentioned this pull request Sep 20, 2016
Closed
@ashercodeorg

ashercodeorg commented Sep 20, 2016

Copy link
Copy Markdown
Contributor

LGTM.

@ashercodeorg

ashercodeorg commented Sep 20, 2016

Copy link
Copy Markdown
Contributor

Should we do an audit and see if there is anywhere else in our codebase missing such an annotation?

@wjordan

wjordan commented Sep 20, 2016

Copy link
Copy Markdown
Contributor Author

yeah, i think an audit-pass through our ActiveRecord models for this sort of easy optimization could be helpful.

@wjordan wjordan merged commit b18f280 into staging Sep 20, 2016
@wjordan wjordan deleted the inverse_of_user_levels branch September 20, 2016 23:28
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

1 more reviewer

@ashercodeorg ashercodeorg ashercodeorg approved these changes

Reviewers whose approvals may not affect merge requirements

Assignees

@ashercodeorg ashercodeorg

@jeremydstone jeremydstone

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

3 participants

@wjordan @ashercodeorg @jeremydstone