Store locale in cookies

app/controllers/application_controller.rb

@@ -1,14 +1,18 @@
 # frozen_string_literal: true
 
 class ApplicationController < ActionController::Base
+  include ParamConverters
+
   before_action :authenticate_auth_user!
   around_action :switch_locale
 
   default_form_builder SkillsFormBuilder
 
   def switch_locale(&)
-    locale = params[:locale] || I18n.default_locale
-    I18n.with_locale(locale, &)
+    param_locale = params[:locale]
+    redirect_to(locale: cookies[:locale] || I18n.default_locale) unless param_locale
+    cookies.permanent[:locale] = param_locale if true?(params[:set_by_user])
+    I18n.with_locale(param_locale, &)
   end
 
   def authenticate_auth_user!
@@ -43,6 +47,6 @@ def render_error(title_key, body_key, status = :bad_request)
   end
 
   def default_url_options
-    { locale: I18n.locale == I18n.default_locale ? nil : I18n.locale }
+    { locale: I18n.locale }
   end
 end

app/helpers/auth_helper.rb

@@ -25,9 +25,9 @@ def devise?
 
   def language_selector
     languages = I18n.available_locales.map { |e| e.to_s }.map do |lang_code|
-      [language(lang_code).capitalize, url_for(locale: lang_code)]
+      [language(lang_code).capitalize, url_for(locale: lang_code, set_by_user: true)]
     end
-    options_for_select(languages, url_for(locale: I18n.locale))
+    options_for_select(languages, url_for(locale: I18n.locale, set_by_user: true))
   end
 
   def language(lang_code)

spec/controllers/people_controller_spec.rb

@@ -23,4 +23,20 @@
       expect(people(:bob).reload.nationality2).to eql("DE")
     end
   end
+
+  describe 'handling of locale' do
+    it 'it should correctly set locale cookie' do
+      # Check if locale cookie is not set by default
+      get :index, params: {locale: :fr}
+      expect(response.cookies['locale']).to be_nil
+
+      # Check if locale cookie is set if it is changed by user
+      get :index, params: {locale: :fr, set_by_user: true}
+      expect(response.cookies['locale']).to eql('fr')
+
+      # Cookie should not be changed if user requests page with other locale
+      get :index, params: {locale: :en}
+      expect(response.cookies['locale']).to be_nil
+    end
+  end
 end

spec/features/routing_spec.rb

@@ -10,10 +10,10 @@
 
   describe "Check auto rerouting" do
     ROUTES = {
-      "/": "/people",
+      "/": "/de/people",
       "/de/": "/de/people",
-      "/people": "/people",
-      "/people_skills": "/people_skills",
+      "/people": "/de/people",
+      "/people_skills": "/de/people_skills",
       "/en": "/en/people",
     }
 
@@ -29,14 +29,25 @@
     context "Set locale via dropdown" do
       before(:each) do
         visit people_path
-        select 'Italiano', from: "i18n_language"
-        default_url_options[:locale] = :it
       end
 
-      it "Should open profile with correct language" do
+      it "Should open profile with correct language and preserve language in cookie" do
+        select 'Italiano', from: "i18n_language"
+
+        select_from_slim_select("#person_id_person", bob.name)
+        expect(page).to have_text("Dati personali")
+
+        # Visiting page with locale explicitly defined in route should use locale from route
+        visit '/en/'
+        select_from_slim_select("#person_id_person", bob.name)
+        expect(page).to have_text("Personal details")
+
+        # Simulate revisit without a locale in the url, which should use locale from cookie
+        visit '/'
+
         select_from_slim_select("#person_id_person", bob.name)
         expect(page).to have_text("Dati personali")
-        click_link(href: person_people_skills_path(bob))
+        click_link(href: person_people_skills_path(bob, locale: :it))
         expect(page).to have_text("Nuove competenze per la valutazione")
       end
     end

spec/features/tabbar_spec.rb

@@ -23,11 +23,11 @@
 
       before(:each) do
         I18n.locale = locale
-        default_url_options[:locale] = I18n.locale == I18n.default_locale ? nil : I18n.locale
+        default_url_options[:locale] = I18n.locale
       end
 
       after(:each) do
-        expect(current_path.start_with?("/#{locale}")).to eq(I18n.locale != I18n.default_locale)
+        expect(current_path).to start_with("/#{locale}")
       end
 
       describe 'Global' do

spec/rails_helper.rb

@@ -90,6 +90,6 @@
   end
 
   config.before(:each, type: :feature) do
-    default_url_options[:locale] = I18n.locale == I18n.default_locale ? nil : I18n.locale
+    default_url_options[:locale] = I18n.locale
   end
 end