Rails：使用 form_with 的语言环境？

Question

How do I use locales and form_with ? By locale I mean /en instead of /?locale=en .

This is part of my view file:

<%= form_with(model: @model, local: true, locale: I18n.locale) do |form| %>

After submitting the form I get the following error:

No route matches {:action=>"show", :controller=>"model_name", :format=>nil, :locale=>#<ModelName id: 2, created_at: "2018-10-15 11:07:36", updated_at: "2018-10-15 11:08:09">}, missing required keys: [:id], possible unmatched constraints: [:locale]

Notice how locale is set with the given model ...

This is my routes.rb :

root 'model_name#new'

scope ':locale', locale: /[a-z]{2}/ do
  root 'model_name#new'
  resources :model_name, only: [:create, :show]
end

I don't understand why I need to set root twice but ...

Thanks!

Answer 1

root inside of scope means the root of the scope.

Example:

root # matches / 
scope ':locale' do
  root # matches /en/
  resources :foos # matches /en/foos, /en/foo/1, ...
end

I suggest you to call rake routes to see what routes you have defined and play around a bit.

And back to the error you are getting. This error means, that the constraint on the scope is not matched. I'd bet, that the locale is empty. according to docs of form_with , you should use scope option, like this:

<%= form_with(model: @model, local: true, scope: I18n.locale) do |form| %>

Answer 2

Rails is using your instance of ModelName because locale isn't set. To be sure that your locale is set in urls, add the default_url_options method to application_controller , where set_locale contains the logic for your application's locale.

def default_url_options
   { locale: set_locale }
end

private def set_locale
  params[:locale] || I18n.default_locale
end

source: https://guides.rubyonrails.org/i18n.html#managing-the-locale-across-requests