Railsの管理画面gem Administrate を使ってみる

$ ruby -v
ruby 3.1.2p20

$ gem install rails

$ rails --version
Rails 7.0.3

$ rails new demo_administrate

$ cd demo_administrate

$ bin/rails g scaffold post title:string body:text published:boolean

$ bin/rails db:create
Database 'db/development.sqlite3' already exists
Created database 'db/test.sqlite3'

$ bin/rails db:migrate
== 20220626030909 CreatePosts: migrating ======================================
-- create_table(:posts)
   -> 0.0027s
== 20220626030909 CreatePosts: migrated (0.0028s) =============================

# add
gem "administrate"

$ bundle install

$ bin/rails generate administrate:install

 Rails.application.routes.draw do
+  namespace :admin do
+    resources :posts
+
+    root to: "posts#index"
+  end
   resources :posts
 end

# All Administrate controllers inherit from this
# `Administrate::ApplicationController`, making it the ideal place to put
# authentication logic or other before_actions.
#
# If you want to add pagination or other controller-level concerns,
# you're free to overwrite the RESTful controller actions.
module Admin
  class ApplicationController < Administrate::ApplicationController
    before_action :authenticate_admin

    def authenticate_admin
      # TODO Add authentication logic here.
    end

    # Override this value to specify the number of elements to display at a time
    # on index pages. Defaults to 20.
    # def records_per_page
    #   params[:per_page] || 20
    # end
  end
end

module Admin
  class PostsController < Admin::ApplicationController
    # Overwrite any of the RESTful controller actions to implement custom behavior
    # For example, you may want to send an email after a foo is updated.
    #
    # def update
    #   super
    #   send_foo_updated_email(requested_resource)
    # end

    # Override this method to specify custom lookup behavior.
    # This will be used to set the resource for the `show`, `edit`, and `update`
    # actions.
    #
    # def find_resource(param)
    #   Foo.find_by!(slug: param)
    # end

    # The result of this lookup will be available as `requested_resource`

    # Override this if you have certain roles that require a subset
    # this will be used to set the records shown on the `index` action.
    #
    # def scoped_resource
    #   if current_user.super_admin?
    #     resource_class
    #   else
    #     resource_class.with_less_stuff
    #   end
    # end

    # Override `resource_params` if you want to transform the submitted
    # data before it's persisted. For example, the following would turn all
    # empty values into nil values. It uses other APIs such as `resource_class`
    # and `dashboard`:
    #
    # def resource_params
    #   params.require(resource_class.model_name.param_key).
    #     permit(dashboard.permitted_attributes).
    #     transform_values { |value| value == "" ? nil : value }
    # end

    # See https://administrate-prototype.herokuapp.com/customizing_controller_actions
    # for more information
  end
end

require "administrate/base_dashboard"

class PostDashboard < Administrate::BaseDashboard
  # ATTRIBUTE_TYPES
  # a hash that describes the type of each of the model's fields.
  #
  # Each different type represents an Administrate::Field object,
  # which determines how the attribute is displayed
  # on pages throughout the dashboard.
  ATTRIBUTE_TYPES = {
    id: Field::Number,
    title: Field::String,
    body: Field::Text,
    published: Field::Boolean,
    created_at: Field::DateTime,
    updated_at: Field::DateTime,
  }.freeze

  # COLLECTION_ATTRIBUTES
  # an array of attributes that will be displayed on the model's index page.
  #
  # By default, it's limited to four items to reduce clutter on index pages.
  # Feel free to add, remove, or rearrange items.
  COLLECTION_ATTRIBUTES = %i[
    id
    title
    body
    published
  ].freeze

  # SHOW_PAGE_ATTRIBUTES
  # an array of attributes that will be displayed on the model's show page.
  SHOW_PAGE_ATTRIBUTES = %i[
    id
    title
    body
    published
    created_at
    updated_at
  ].freeze

  # FORM_ATTRIBUTES
  # an array of attributes that will be displayed
  # on the model's form (`new` and `edit`) pages.
  FORM_ATTRIBUTES = %i[
    title
    body
    published
  ].freeze

  # COLLECTION_FILTERS
  # a hash that defines filters that can be used while searching via the search
  # field of the dashboard.
  #
  # For example to add an option to search for open resources by typing "open:"
  # in the search field:
  #
  #   COLLECTION_FILTERS = {
  #     open: ->(resources) { resources.where(open: true) }
  #   }.freeze
  COLLECTION_FILTERS = {}.freeze

  # Overwrite this method to customize how posts are displayed
  # across all pages of the admin dashboard.
  #
  # def display_resource(post)
  #   "Post ##{post.id}"
  # end
end

$ bin/rails s
$ open http://localhost:3000/admin

 module DemoAdministrate
   class Application < Rails::Application
    # ...
+   config.i18n.default_locale = :ja
   end
 end

ja:
  activerecord:
    models:
      post: 投稿
    attributes:
      post:
        title: タイトル
        body: 本文
        published: 公開
        created_at: 作成日時
        updated_at: 更新日時

 module Admin
   class ApplicationController < Administrate::ApplicationController
+    before_action :authenticate_admin_user!
-    before_action :authenticate_admin

-    def authenticate_admin
-      # TODO Add authentication logic here.
-    end
   end
 end

$ bin/rails generate scaffold tag post:references name:string
$ bin/rails db:migrate

$ bin/rails generate administrate:dashboard Tag

 Rails.application.routes.draw do
   resources :posts
   resources :tags

   namespace :admin do
       resources :posts
+      resources :tags

       root to: "posts#index"
     end
 end

 require "administrate/base_dashboard"

 class TagDashboard < Administrate::BaseDashboard
   ATTRIBUTE_TYPES = {
     post: Field::BelongsTo,
     id: Field::Number,
     name: Field::String,
     created_at: Field::DateTime,
     updated_at: Field::DateTime,
   }.freeze

   COLLECTION_ATTRIBUTES = %i[
-    post
     id
     name
+    post
     created_at
   ].freeze

   SHOW_PAGE_ATTRIBUTES = %i[
-    post
     id
     name
+    post
     created_at
     updated_at
   ].freeze

   FORM_ATTRIBUTES = %i[
-    post
     name
+    post
   ].freeze

   COLLECTION_FILTERS = {}.freeze

   # def display_resource(tag)
   #   "Tag ##{tag.id}"
   # end
 end

 require "administrate/base_dashboard"

 class PostDashboard < Administrate::BaseDashboard

   # ...

   def display_resource(post)
-    "Post ##{post.id}"
+    "Post ##{post.id} #{post.title}"
   end
 end