Store locale in a user's field and switch locale on mailers

app/controllers/application_controller.rb

@@ -52,7 +52,14 @@ class ApplicationController < ActionController::Base
 
       session[:locale] ||= I18n.default_locale
 
-      I18n.locale = session[:locale]
+      locale = session[:locale]
+
+      if current_user
+        current_user.locale = locale
+        current_user.save
+      end
+
+      I18n.locale = locale
     end
 
     def set_layout

app/controllers/users/registrations_controller.rb

@@ -47,7 +47,9 @@ class Users::RegistrationsController < Devise::RegistrationsController
   private
 
     def sign_up_params
-      params.require(:user).permit(:username, :email, :password, :password_confirmation, :captcha, :captcha_key, :terms_of_service)
+      params.require(:user).permit(:username, :email, :password,
+                                   :password_confirmation, :captcha,
+                                   :captcha_key, :terms_of_service, :locale)
     end
 
     def erase_params

app/mailers/devise_mailer.rb

@@ -0,0 +1,13 @@
+class DeviseMailer < Devise::Mailer
+  helper :application
+  include Devise::Controllers::UrlHelpers
+  default template_path: 'devise/mailer'
+
+  protected
+
+  def devise_mail(record, action, opts={})
+    I18n.with_locale record.locale do
+      super(record, action, opts)
+    end
+  end
+end

app/mailers/mailer.rb

@@ -6,16 +6,20 @@ class Mailer < ApplicationMailer
   def comment(comment)
     @comment = comment
     @commentable = comment.commentable
+    with_user(@commentable.author) do
       mail(to: @commentable.author.email, subject: t('mailers.comment.subject', commentable: t("activerecord.models.#{@commentable.class.name.downcase}", count: 1).downcase)) if @commentable.present? && @commentable.author.present?
     end
+  end
 
   def reply(reply)
     @reply = reply
     @commentable = @reply.commentable
     parent = Comment.find(@reply.parent_id)
     @recipient = parent.author
+    with_user(@recipient) do
       mail(to: @recipient.email, subject: t('mailers.reply.subject')) if @commentable.present? && @recipient.present?
     end
+  end
 
   def email_verification(user, recipient, token, document_type, document_number)
     @user = user
@@ -23,7 +27,17 @@ class Mailer < ApplicationMailer
     @token = token
     @document_type = document_type
     @document_number = document_number
+
+    with_user(user) do
       mail(to: @recipient, subject: t('mailers.email_verification.subject'))
     end
+  end
 
+  private
+
+  def with_user(user, &block)
+    I18n.with_locale(user.locale) do
+      block.call
+    end
+  end
 end

app/models/user.rb

@@ -34,6 +34,9 @@ class User < ActiveRecord::Base
   validates_format_of :email, without: OMNIAUTH_EMAIL_REGEX, on: :update
   validates :terms_of_service, acceptance: { allow_nil: false }, on: :create
 
+  validates :locale, inclusion: {in: I18n.available_locales.map(&:to_s),
+                                 allow_nil: true}
+
   validates_associated :organization, message: false
 
   accepts_nested_attributes_for :organization, update_only: true
@@ -206,6 +209,10 @@ class User < ActiveRecord::Base
     !email.blank? && ( (email.end_with? "@#{domain}") || (email.end_with? ".#{domain}") )
   end
 
+  def locale
+    self[:locale] ||= I18n.default_locale.to_s
+  end
+
   private
     def clean_document_number
       self.document_number = self.document_number.gsub(/[^a-z0-9]+/i, "").upcase unless self.document_number.blank?

app/views/users/registrations/new.html.erb

@@ -27,6 +27,8 @@
                            label: t("devise_views.users.registrations.new.password_confirmation_label"),
                            placeholder: t("devise_views.users.registrations.new.password_confirmation_label") %>
 
+      <%= f.hidden_field :locale, value: I18n.locale %>
+
       <%= f.simple_captcha input_html: {required: false} %>
 
 

config/initializers/devise.rb

@@ -15,7 +15,7 @@ Devise.setup do |config|
   config.mailer_sender = 'noreply@madrid.es'
 
   # Configure the class responsible to send e-mails.
-  # config.mailer = 'Devise::Mailer'
+  config.mailer = 'DeviseMailer'
 
   # ==> ORM configuration
   # Load and configure the ORM. Supports :active_record (default) and

db/migrate/20160122153329_add_locale_to_users.rb

@@ -0,0 +1,5 @@
+class AddLocaleToUsers < ActiveRecord::Migration
+  def change
+    add_column :users, :locale, :string
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160114110933) do
+ActiveRecord::Schema.define(version: 20160122153329) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -391,6 +391,7 @@ ActiveRecord::Schema.define(version: 20160114110933) do
     t.boolean  "public_activity",                      default: true
     t.boolean  "newsletter",                           default: false
     t.integer  "notifications_count",                  default: 0
+    t.string   "locale"
   end
 
   add_index "users", ["confirmation_token"], name: "index_users_on_confirmation_token", unique: true, using: :btree

spec/features/emails_spec.rb

@@ -112,4 +112,13 @@ feature 'Emails' do
     end
   end
 
+  scenario "Email depending on user's locale" do
+    sign_up
+
+    email = open_last_email
+    expect(email).to have_subject('Confirmation instructions')
+    expect(email).to deliver_to('manuela@madrid.es')
+    expect(email).to have_body_text(user_confirmation_path)
+  end
+
 end

spec/mailers/devise_mailer_spec.rb

@@ -0,0 +1,16 @@
+# coding: utf-8
+require 'rails_helper'
+
+describe DeviseMailer do
+  describe "#confirmation_instructions" do
+    it "sends emails in the user's locale" do
+      user = create(:user, locale: "es")
+
+      email = I18n.with_locale :en do
+        DeviseMailer.confirmation_instructions(user, "ABC")
+      end
+
+      expect(email.subject).to include("confirmación")
+    end
+  end
+end

spec/mailers/mailer_spec.rb

@@ -0,0 +1,17 @@
+require 'rails_helper'
+
+describe Mailer do
+  describe "#comment" do
+    it "sends emails in the user's locale" do
+      user = create(:user, locale: "es")
+      proposal = create(:proposal, author: user)
+      comment = create(:comment, commentable: proposal)
+
+      email = I18n.with_locale :en do
+        Mailer.comment(comment)
+      end
+
+      expect(email.subject).to include("comentado")
+    end
+  end
+end