This Week in Rails

May 23, 2025

Rails World 2025 speaker lineup, deprecations, doc updates and more!

Hello! Emmanuel Hayford here.

The third edition of Rails World is a couple of months away! In case you missed it, The Rails Foundation has already announced an exciting lineup that you should check out.


Document `through` with `polymorphic`
A new addition to the Rails documentation clarifies that polymorphic associations are not supported as :through associations. While Active Record already raises an error when such a setup is attempted, the exceptions were previously undocumented. This update makes the restriction explicit in the docs.


Deprecate `:class_name` for polymorphic `belongs_to`
Passing `:class_name` to a polymorphic `belongs_to` is now deprecated and will be removed in Rails 8.1. Since the associated class is already determined by the type column, the option is unnecessary. If you're using `:class_name` in this context, you can safely delete it.


Add namespaced version of the `db:migrate:reset` command
Rails now supports a namespaced version of `db:migrate:reset`, allowing you to reset only the primary database using `db:migrate:reset:primary`.


Respect `SCHEMA_FORMAT` in `db:schema:load`
A fix has been applied to ensure the `SCHEMA_FORMAT` environment variable behaves as described in the task description. This correction only applies to Rails 7.2 and addresses an oversight from its initial introduction.

You can view the whole list of changes here.
We had 17 contributors to the Rails codebase this past week!

Until next time!

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About This Week in Rails

Your weekly inside scoop of interesting commits, pull requests and more from Rails.