Add TWIR 23.05.25 (#499)

* Add TWIR 23.05.25

* Format titles

Author: siaw23

_posts/2025-05-23-this-week-in-rails.markdown

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+---
+layout: post
+title: "Rails World 2025 speaker lineup, deprecations, doc updates and more!"
+categories: news
+author: Emmanuel Hayford
+og_image: assets/images/this-week-in-rails.png
+published: true
+date: 2025-05-23
+---
+
+
+Hello! [Emmanuel Hayford](https://x.com/siaw23) 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](https://rubyonrails.org/2025/5/20/rails-world-2025-speakers) that you should check out in case you haven't seen it yet.
+
+
+[Document `through` with `polymorphic`](https://github.com/rails/rails/pull/55107)
+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`](https://github.com/rails/rails/pull/55091)
+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.](https://github.com/rails/rails/pull/55077)
+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`](https://github.com/rails/rails/pull/55059)
+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](https://github.com/rails/rails/compare/@%7B2025-05-16%7D...main@%7B2025-05-23%7D)._
+_We had [17 contributors](https://contributors.rubyonrails.org/contributors/in-time-window/20250516-20250523) to the Rails codebase this past week!_
+
+Until next time!
+
+_[Subscribe](https://world.hey.com/this.week.in.rails) to get these updates mailed to you._