Add locale URL redirection

When processing requests for URLs where the locale is a prefix, we now:
1. Redirect to the same URL with the locale as a parameter, this is done
   via routing redirects.

2. Set the locale in the session. This is done in the existing
   `set_gettext_locale` before action callback.

3. Finally, we redirect to the same URL without the locale at all as
   this information is retrieved from the session or cookies.

The redirect is skipped for the `PublicBodyController#show` action as
there is already redirection in place there to redirect to localised
version of the `PublicBody#url_name`.

app/controllers/application_controller.rb

@@ -13,7 +13,7 @@ class PermissionDenied < StandardError
   class RouteNotFound < StandardError
   end
 
-  before_action :set_gettext_locale
+  before_action :set_gettext_locale, :redirect_gettext_locale
   before_action :collect_locales
 
   protect_from_forgery if: :authenticated?, with: :exception
@@ -81,6 +81,9 @@ def set_gettext_locale
       AlaveteliLocalization.default_locale
     )
 
+    # set response header informing the browser what language the page is in
+    response.headers['Content-Language'] = I18n.locale.to_s
+
     # set the current stored locale to the requested_locale
     current_session_locale = session[:locale]
     if current_session_locale != locale
@@ -95,6 +98,11 @@ def set_gettext_locale
     current_user.update_columns(locale: locale) if current_user
   end
 
+  def redirect_gettext_locale
+    # redirect to remove locale params if present
+    redirect_to current_path_without_locale if params[:locale]
+  end
+
   # Help work out which request causes RAM spike.
   # http://www.codeweblog.com/rails-to-monitor-the-process-of-memory-leaks-skills/
   # This shows the memory use increase of the Ruby process due to the request.

app/controllers/public_body_controller.rb

@@ -8,6 +8,7 @@
 
 class PublicBodyController < ApplicationController
   skip_before_action :html_response, only: [:show, :list_all_csv]
+  skip_before_action :redirect_gettext_locale, only: :show
 
   MAX_RESULTS = 500
   # TODO: tidy this up with better error messages, and a more standard infrastructure for the redirect to canonical URL

config/routes/redirects.rb

@@ -74,3 +74,24 @@
 get '/:prefix/request/:url_title',
   constraints: { prefix: 'categorise' },
   to: info_request_redirect
+
+locale_constraint = ->(request) do
+  path_locale = request.path.split('/')[1]
+  begin
+    locale = AlaveteliLocalization::Locale.parse(path_locale).canonicalize
+    available = AlaveteliConfiguration.available_locales.split(' ').map do |l|
+      AlaveteliLocalization::Locale.parse(l).canonicalize
+    end
+    available.include?(locale)
+  rescue ArgumentError
+    false
+  end
+end
+
+get ':locale',
+  constraints: locale_constraint,
+  to: redirect('?locale=%{locale}')
+
+get ':locale/*path',
+  constraints: locale_constraint,
+  to: redirect('%{path}?locale=%{locale}')

spec/controllers/admin_public_body_controller_spec.rb

@@ -14,7 +14,7 @@
     end
 
     it "searches for 'humpa' in another locale" do
-      get :index, params: { query: "humpa", locale: "es" }
+      get :index, params: { query: "humpa" }, session: { locale: "es" }
       expect(assigns[:public_bodies]).
         to eq([public_bodies(:humpadink_public_body)])
     end
@@ -45,7 +45,7 @@
         public_body.save!
       end
       sign_in admin_user
-      get :show, params: { id: public_body.id, locale: "es" }
+      get :show, params: { id: public_body.id }, session: { locale: 'es' }
       expect(assigns[:public_body].name).to eq 'El Public Body'
     end
 
@@ -329,7 +329,7 @@
     end
 
     it "edits a public body in another locale" do
-      get :edit, params: { id: 3, locale: :en }
+      get :edit, params: { id: 3 }, session: { locale: 'en' }
 
       # When editing a body, the controller returns all available translations
       expect(assigns[:public_body].find_translation_by_locale("es").name).

spec/controllers/general_controller_spec.rb

@@ -143,7 +143,7 @@
 
   describe 'when using locales' do
     it "should use our test PO files rather than the application one" do
-      get :frontpage, params: { locale: 'es' }
+      get :frontpage, session: { locale: 'es' }
       expect(response.body).to match(/XOXO/)
     end
   end

spec/controllers/help_controller_spec.rb

@@ -74,7 +74,7 @@
       end
 
       it 'should render the locale-specific template if available' do
-        get :contact, params: { locale: 'es' }
+        get :contact, session: { locale: 'es' }
         expect(response.body).to match('contáctenos theme one')
       end
     end

spec/controllers/public_body_controller_spec.rb

@@ -53,15 +53,15 @@
   end
 
   it "should display the body using same locale as that used in url_name" do
-    get :show, params: { url_name: "edfh", view: 'all', locale: "es" }
+    get :show, params: { url_name: "edfh", view: 'all' },
+               session: { locale: 'es' }
     expect(response.body).to have_content("Baguette")
   end
 
   it 'should show public body names in the selected locale language if present for a locale with underscores' do
     AlaveteliLocalization.set_locales('he_IL en', 'en')
-    get :show, params: { url_name: 'dfh',
-                         view: 'all',
-                         locale: 'he_IL' }
+    get :show, params: { url_name: 'dfh', view: 'all' },
+               session: { locale: 'he_IL' }
     expect(response.body).to have_content('Hebrew Humpadinking')
   end
 
@@ -147,7 +147,7 @@ def make_single_language_example(locale)
   it "with no fallback, should only return bodies from the current locale" do
     @english_only = make_single_language_example :en
     @spanish_only = make_single_language_example :es
-    get :list, params: { locale: 'es' }
+    get :list, session: { locale: 'es' }
     expect(assigns[:public_bodies].include?(@english_only)).to eq(false)
     expect(assigns[:public_bodies].include?(@spanish_only)).to eq(true)
   end
@@ -157,7 +157,7 @@ def make_single_language_example(locale)
       to receive(:public_body_list_fallback_to_default_locale).
       and_return(true)
     @english_only = make_single_language_example :en
-    get :list, params: { locale: 'es' }
+    get :list, session: { locale: 'es' }
     expect(assigns[:public_bodies].include?(@english_only)).to eq(true)
   end
 
@@ -166,36 +166,36 @@ def make_single_language_example(locale)
       to receive(:public_body_list_fallback_to_default_locale).
       and_return(true)
     @spanish_only = make_single_language_example :es
-    get :list, params: { locale: 'es' }
+    get :list, session: { locale: 'es' }
     expect(assigns[:public_bodies].include?(@spanish_only)).to eq(true)
   end
 
   it "if fallback is requested, make sure that there are no duplicates listed" do
     allow(AlaveteliConfiguration).
       to receive(:public_body_list_fallback_to_default_locale).
       and_return(true)
-    get :list, params: { locale: 'es' }
+    get :list, session: { locale: 'es' }
     pb_ids = assigns[:public_bodies].map(&:id)
     unique_pb_ids = pb_ids.uniq
     expect(pb_ids.sort).to eq(unique_pb_ids.sort)
   end
 
   it 'should show public body names in the selected locale language if present' do
-    get :list, params: { locale: 'es' }
+    get :list, session: { locale: 'es' }
     expect(response.body).to have_content('El Department for Humpadinking')
   end
 
   it 'show public body names of the selected underscore locale language' do
     AlaveteliLocalization.set_locales(available_locales='en en_GB',
                                       default_locale='en')
     @gb_only = make_single_language_example :en_GB
-    get :list, params: { locale: 'en_GB' }
+    get :list, session: { locale: 'en_GB' }
     expect(response.body).to have_content(@gb_only.name)
   end
 
   it 'should not show the internal admin authority' do
     PublicBody.internal_admin_body
-    get :list, params: { locale: 'en' }
+    get :list, session: { locale: 'en' }
     expect(response.body).not_to have_content('Internal admin authority')
   end
 
@@ -206,7 +206,7 @@ def make_single_language_example(locale)
     allow(AlaveteliConfiguration).
       to receive(:public_body_list_fallback_to_default_locale).
       and_return(true)
-    get :list, params: { locale: 'es' }
+    get :list, session: { locale: 'es' }
     parsed = Nokogiri::HTML(response.body)
     public_body_names = parsed.xpath '//span[@class="head"]/a/text()'
     public_body_names = public_body_names.map(&:to_s)
@@ -215,7 +215,7 @@ def make_single_language_example(locale)
 
   it 'should show public body names in the selected locale language if present for a locale with underscores' do
     AlaveteliLocalization.set_locales('he_IL en', 'en')
-    get :list, params: { locale: 'he_IL' }
+    get :list, session: { locale: 'he_IL' }
     expect(response.body).to have_content('Hebrew Humpadinking')
   end
 
@@ -248,7 +248,7 @@ def make_single_language_example(locale)
       with(an_instance_of(String)).
         and_return(true)
 
-    get :list, params: { locale: 'en_GB' }
+    get :list, session: { locale: 'en_GB' }
     expect(assigns[:public_bodies].to_sql).to include('COLLATE')
   end
 
@@ -261,7 +261,7 @@ def make_single_language_example(locale)
       with(an_instance_of(String)).
         and_return(false)
 
-    get :list, params: { locale: 'unknown' }
+    get :list, session: { locale: 'unknown' }
 
     expect(assigns[:public_bodies].to_sql).to_not include('COLLATE')
   end
@@ -275,7 +275,7 @@ def make_single_language_example(locale)
       with(an_instance_of(String)).
         and_return(true)
 
-    get :list, params: { locale: 'en_GB' }
+    get :list, session: { locale: 'en_GB' }
 
     expect(assigns[:public_bodies].to_sql).to include('COLLATE')
   end
@@ -289,7 +289,7 @@ def make_single_language_example(locale)
       with(an_instance_of(String)).
         and_return(false)
 
-    get :list, params: { locale: 'unknown' }
+    get :list, session: { locale: 'unknown' }
 
     expect(assigns[:public_bodies].to_sql).to_not include('COLLATE')
   end
@@ -429,7 +429,7 @@ def make_single_language_example(locale)
       FactoryBot.create(:public_body, name: "Åčçèñtéd Authority")
     end
 
-    get :list, params: { tag: "å", locale: 'cs' }
+    get :list, params: { tag: "å" }, session: { locale: 'cs' }
     expect(response).to render_template('list')
     expect(assigns[:public_bodies]).to eq([ authority ])
     expect(assigns[:tag]).to eq("Å")

spec/integration/errors_spec.rb

@@ -82,7 +82,9 @@
 
     it 'should assign the locale for the general/exception_caught template' do
       allow(InfoRequest).to receive(:find_by_url_title!).and_raise("An example error")
-      get "/request/example?locale=es"
+      get "/es"
+      follow_redirect!
+      get "/request/example"
       expect(response).to render_template('general/exception_caught')
       expect(response.body).to match('Lo sentimos, hubo un problema procesando esta página')
     end