Optional route params not included in translated URL

[seanabrahams]

Steps to reproduce*

rails new optional

config/initializers/i18n.rb

I18n.available_locales = %i[en es]
I18n.default_locale = :en

routes.rb

Rails.application.routes.draw do
  localized do
    get "posts(/page/:page(/items/:items))", controller: :posts, action: :index, as: :posts
    root "posts#index"
  end
end

app/controllers/posts_controller.rb

class PostsController < ApplicationController
end

app/views/posts/index.html.erb - taken from https://github.com/enriclluelles/route_translator/wiki/Generating-translated-URLs

<% I18n.available_locales.each do |locale| %>
  <%= link_to locale, url_for(locale: locale.to_s, only_path: true), rel: 'alternate', hreflang: locale.to_s %>
<% end %>

Expected behavior*

If you load /posts/page/2 the link to the es translated URL should be /es/posts/page/2

Actual behavior*

If you load /posts/page/2 the link to the es translated URL will be /es/posts

System configuration*

Rails version: Rails 7.0.3.1
Ruby version: ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [aarch64-linux]
Route Translator version: route_translator (12.1.0)

I18n configuration*

I18n.available_locales = %i[en es]
I18n.default_locale = :en

Route Translator initializier

Did not create one.

Source code of routes.rb*

Source of: config/routes.rb

Rails.application.routes.draw do
  localized do
    get "posts(/page/:page(/items/:items))", controller: :posts, action: :index, as: :posts
    root "posts#index"
  end
end

Output of rails routes*

Result of bundle exec rails routes:

posts_es GET /es/posts(/page/:page(/items/:items))(.:format)  posts#index {:locale=>"es"}
posts_en GET /posts(/page/:page(/items/:items))(.:format)  posts#index {:locale=>"en"}
root_es  GET /es  posts#index {:locale=>"es"}
root_en  GET /  posts#index {:locale=>"en"}

[tagliala]

Hi!

Thanks for being part of the Route Translator community and apologies for the late reply

I think this issue is not related to Route Translator but it depends on how url_for works for routes with optional parameters

Example on a basic Rails application without Route Translator:

# routes.rb
Rails.application.routes.draw do
  get "posts(/page/:page(/items/:items))", controller: :posts, action: :index, as: :posts
end

<!-- index.html.erb -->
<%= url_for %>

Url: http://localhost:3000/posts/page/2

Output: /posts

I will clarify in the Wiki that url_for works for basic use cases and that optional route parameters are not taken into account

It is possible to force the params by using

<%= url_for(**params.permit!) # DON'T %>

but I would not do that. Probably this use case requires a custom url generation technique

Hope it helps

Closing here, but feel free to comment

[seanabrahams]

Thank you for the response, updating the Wiki page, and for keeping this gem in good shape. Appreciate it.