activeadmin+paperclipで画像管理機能導入メモ

#メモなのでところどころ怪しいです

参考（詳しい）

• http://morizyun.github.io/blog/active-admin-gem-rails/
• http://ruby-rails.hatenadiary.com/entry/20140716/1405443484
• http://qiita.com/hkusu/items/3b0fb7f94a254e2ed6fd

前提

• すでに activeadmin 導入済み（ /admin が使える）
• Imagemagickいれておく（$ brew install imagemagick）

paperclip導入

Gemfile

gem 'paperclip'

Pictureモデル準備

$ bundle exec rails g picture name:string photo:attachment
$ bundle exec rake db:migrate

db/migrate/20150228120636_create_pictures.rb

class CreatePictures < ActiveRecord::Migration
  def change
    create_table :pictures do |t|
      t.string :name
      t.attachment :photo

      t.timestamps
    end
  end
end

app/models/picture.rb

class Picture < ActiveRecord::Base

  has_attached_file :photo, styles: { medium: "300x300>", thumb: "100x100>" }
  validates_attachment :photo, content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"] }

end

ActiveAdminに追加

$ bundle exec rails g active_admin:resource Picture

app/admin/picture.rb

ActiveAdmin.register Picture do
  permit_params :id, :name, :photo

  index do
    column "ID", :id
    column "name", :name
    column "thumb", :photo do |obj|
      image_tag(obj.photo.url(:thumb))
    end
    actions
  end

  form multipart: true do |f|
    f.inputs Picture do
      f.input :name
      f.input :photo, as: :file, hint: image_tag(f.object.photo.url(:medium))

      f.actions
    end
  end

  show do |b|
    attributes_table do
      row :name
      row :photo do
        image_tag(b.photo.url(:medium))
      end
      row :url do
        b.photo.url
      end
      row :url_medium do
        b.photo.url(:medium)
      end
      row :url_thumb do
        b.photo.url(:thumb)
      end
    end
    active_admin_comments
  end

end

ほかのModelにも似たような手順で機能追加できそう。