Set locale through controller filter

app/controllers/application_controller.rb

@@ -265,4 +265,10 @@ class ApplicationController < ActionController::Base
   def u2f_app_id
     request.base_url
   end
+
+  def set_locale
+    requested_locale = current_user&.preferred_language || request.env['HTTP_ACCEPT_LANGUAGE'] || I18n.default_locale
+    locale = FastGettext.set_locale(requested_locale)
+    I18n.locale = locale
+  end
 end

app/controllers/profiles_controller.rb

@@ -3,6 +3,7 @@ class ProfilesController < Profiles::ApplicationController
   before_action :user
   before_action :authorize_change_username!, only: :update_username
+  before_action :set_locale, only: :show
   skip_before_action :require_email, only: [:show, :update]
   def show

app/views/profiles/show.html.haml

@@ -74,7 +74,8 @@
         %span.help-block This email will be displayed on your public profile.
       .form-group
         = f.label :preferred_language, class: "label-light"
-        = f.select :preferred_language, Gitlab::I18n::AVAILABLE_LANGUAGES, {}, class: "select2"
+        = f.select :preferred_language, Gitlab::I18n::AVAILABLE_LANGUAGES.map { |lang| [_(lang[0]), lang[1]] },
+          {}, class: "select2"
       .form-group
         = f.label :skype, class: "label-light"
         = f.text_field :skype, class: "form-control"

lib/gitlab/i18n.rb

 module Gitlab
   module I18n
     AVAILABLE_LANGUAGES = [
-      [_('English'), 'en'],
-      [_('Spanish'), 'es'],
-      [_('Deutsch'), 'de']
+      ['English', 'en'],
+      ['Spanish', 'es'],
+      ['Deutsch', 'de']
     ]
   end
 end

locale/de/gitlab.edit.po

@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: gitlab 1.0.0\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2017-04-12 22:36-0500\n"
+"POT-Creation-Date: 2017-04-13 00:01-0500\n"
 "PO-Revision-Date: 2017-04-12 22:37-0500\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: German\n"
@@ -17,3 +17,12 @@ msgstr ""
 "Content-Transfer-Encoding: 8bit\n"
 "Plural-Forms: nplurals=2; plural=n != 1;\n"
 "\n"
+
+msgid "Deutsch"
+msgstr ""
+
+msgid "English"
+msgstr ""
+
+msgid "Spanish"
+msgstr ""

locale/de/gitlab.po

@@ -16,3 +16,12 @@ msgstr ""
 "Content-Transfer-Encoding: 8bit\n"
 "Plural-Forms: nplurals=2; plural=n != 1;\n"
 "\n"
+
+msgid "Deutsch"
+msgstr ""
+
+msgid "English"
+msgstr ""
+
+msgid "Spanish"
+msgstr ""

locale/en/gitlab.edit.po

@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: gitlab 1.0.0\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2017-04-12 22:36-0500\n"
+"POT-Creation-Date: 2017-04-13 00:01-0500\n"
 "PO-Revision-Date: 2017-04-12 22:36-0500\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: English\n"
@@ -17,3 +17,12 @@ msgstr ""
 "Content-Transfer-Encoding: 8bit\n"
 "Plural-Forms: nplurals=2; plural=n != 1;\n"
 "\n"
+
+msgid "Deutsch"
+msgstr ""
+
+msgid "English"
+msgstr ""
+
+msgid "Spanish"
+msgstr ""

locale/en/gitlab.po

@@ -16,3 +16,12 @@ msgstr ""
 "Content-Transfer-Encoding: 8bit\n"
 "Plural-Forms: nplurals=2; plural=n != 1;\n"
 "\n"
+
+msgid "Deutsch"
+msgstr ""
+
+msgid "English"
+msgstr ""
+
+msgid "Spanish"
+msgstr ""

locale/es/gitlab.edit.po

@@ -7,13 +7,22 @@ msgid ""
 msgstr ""
 "Project-Id-Version: gitlab 1.0.0\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2017-04-12 22:36-0500\n"
-"PO-Revision-Date: 2017-04-12 22:37-0500\n"
-"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"PO-Revision-Date: 2017-04-13 00:07-0500\n"
 "Language-Team: Spanish\n"
 "Language: es\n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "Plural-Forms: nplurals=2; plural=n != 1;\n"
-"\n"
+"POT-Creation-Date: 2017-04-13 00:01-0500\n"
+"Last-Translator: \n"
+"X-Generator: Poedit 2.0.1\n"
+
+msgid "Deutsch"
+msgstr "Alemán"
+
+msgid "English"
+msgstr "Inglés"
+
+msgid "Spanish"
+msgstr "Español"

locale/es/gitlab.po

@@ -7,12 +7,21 @@ msgid ""
 msgstr ""
 "Project-Id-Version: gitlab 1.0.0\n"
 "Report-Msgid-Bugs-To: \n"
-"PO-Revision-Date: 2017-04-12 22:37-0500\n"
-"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"PO-Revision-Date: 2017-04-13 00:07-0500\n"
 "Language-Team: Spanish\n"
 "Language: es\n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "Plural-Forms: nplurals=2; plural=n != 1;\n"
-"\n"
+"Last-Translator: \n"
+"X-Generator: Poedit 2.0.1\n"
+
+msgid "Deutsch"
+msgstr "Alemán"
+
+msgid "English"
+msgstr "Inglés"
+
+msgid "Spanish"
+msgstr "Español"

locale/gitlab.pot

@@ -8,8 +8,8 @@ msgid ""
 msgstr ""
 "Project-Id-Version: gitlab 1.0.0\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2017-04-12 22:36-0500\n"
-"PO-Revision-Date: 2017-04-12 22:36-0500\n"
+"POT-Creation-Date: 2017-04-13 00:01-0500\n"
+"PO-Revision-Date: 2017-04-13 00:01-0500\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
 "Language: \n"
@@ -17,3 +17,12 @@ msgstr ""
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
 "Plural-Forms: nplurals=INTEGER; plural=EXPRESSION;\n"
+
+msgid "Deutsch"
+msgstr ""
+
+msgid "English"
+msgstr ""
+
+msgid "Spanish"
+msgstr ""