Rails link to current page and passing parameters to it

Question

I am adding I18N to my rails application by passing the locale using url params. My urls are looking like http://example.com/en/users and http://example.com/ar/users (for th

Answer 1

You can safely use url_for to switch locales with url params if you set only_path: true:

<%= link_to I18n.t('language_name', locale: I18n.locale), url_for( params.clone.permit!.merge(locale: locale, only_path: true ) %>

We .clone the params before permitting them all (.permit!), to preserve strong parameters elsewhere. The only more secure solution I could find would be to time consumingly whitelist all params instead...

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Robust I18n implementation:

Add a locales.rb initializer to define what I18n.available_locales you support:

# config/initializers/locales.rb

# Permitted locales available for the application
I18n.available_locales = [:en, :fr]

Set a language_name value in each language's locale file (e.g. fr.yml):

fr:
  language_name: "Français"

As you add more languages, this ERB will let you generically switch between them:

  // app/views/layouts/_languages.html.erb
  
   <% I18n.available_locales.each do |locale| %>
      <% if I18n.locale == locale %>
        <%= link_to I18n.t('language_name', locale: locale), url_for( params.clone.permit!.merge(locale: locale, only_path: true ), {style: "display:none" } %>
      <% else %>
        <%= link_to I18n.t('language_name', locale: locale), url_for( params.clone.permit!.merge(locale: locale, only_path: true ) %>
      <% end %>
    <% end %>
  

For the controller, we automatically find the correct language for the user by detecting their browser's Accept-Language HTTP header (using the http_accept_language gem).

Set a session cookie to preserve locale across requests.

Or optionally, use default_url_options to insert the ?locale= param into your app's url. I do both.

Controller:

class ApplicationController < ActionController::Base
  before_action :set_locale

  private

  def set_locale
    I18n.locale = begin
      extract_locale ||
        session[:locale] ||
          http_accept_language.compatible_language_from(I18n.available_locales) ||
            I18n.default_locale
    end
    session[:locale] = I18n.locale
  end

  def extract_locale
    parsed_locale = params[:locale].dup
    I18n.available_locales.map(&:to_s).include?(parsed_locale) ? parsed_locale : nil
  end

  def default_url_options
    { locale: I18n.locale }
  end
end