[Rails] How to use Gem'rails-i18n' for Japanese support

Purpose

Use Gem'rails-i18n'to support Japanese. Make a note of the clogged part when introducing this Gem.

Development environment

・ Ruby 2.6.4 ・ Rails 5.2.3

Reference material

Rails Internationalization (i18n) API

Japanese localization by Rails i18n

[I18n :: InvalidLocaleData Locale file cannot be translated] (https://qiita.com/niwa1903/items/10154b8cbe1cd0416495)

Installation procedure

① Install gem'rails-i18n'.

Gemfile.

gem 'rails-i18n', '~> 5.1'

$ bundle install

This is the usual flow when installing Rails Gem.

(2) Set the default language to Japanese. Then, pass the path so that i18n's multiple locale files are read.

config/application.rb

module App
  class Application < Rails::Application
    # Initialize configuration defaults for originally generated Rails version.
    config.load_defaults 5.2

    #2 lines added:The default locale is Japanese(:ja)To.
    config.i18n.default_locale = :ja
    config.i18n.load_path += Dir[Rails.root.join('config', 'locales', '**', '*.{rb,yml}').to_s]
  end
end

Add two lines in the module. Without this description, it seems that even if you install Gem, it will not support Japanese.

③ Create a ja.yml file in the locales folder

・ Japanese support for model

config/locales/activerecord/ja.yml

ja:
    activerecord:
     models:
       user: 'user'
       board: 'Bulletin board'
     attributes:
       user:
         email: 'mail address'
         password: 'password'
         password_confirmation: 'Password confirmation'
         last_name: 'Surname'
         first_name: 'Name'

To make it correspond to the entire model, create a hierarchy of models and When associating column names, create a hierarchy of attributes.

・ Japanese support for view and controller

config/locales/view/ja.yml

ja:
   users:
     new:
       title: 'user registration'
       to_login_page: 'Go to login page'
     create:
      success: 'User registration is complete'
      fail: 'User registration failed'

By describing it in view/ja.yml, it is also applied to controller. However, if you do not create a hierarchical structure with exactly two indents, Japanese will not be applied.

For how to write ja.yml, the following Rails guide article will be helpful. Lazy lookup

④ Display the set Japanese with view or controller

ja:
  books:
    index:
      title: "Hogehoge"

With the above hierarchical structure, you can access the books.index.title value inside the app/views/books/index.html.erb view template as follows:

<%= t '.title' %>Or<%= t ('.title') %>

If you write it in full, it will be as follows.

<%= t 'books.index.title' %>

You should now be able to speak Japanese using Gem'rails-i18n'!