うーん jquery と helperの組み合わせはみんなどう書いてるんだろう、、、

app/assets/javascripts/application.js

@@ -15,3 +15,25 @@
 //= require bootstrap
 //= require turbolinks
 //= require_tree .
+$(document).ready(function(){
+  $(".like").on('click', function(ev){
+    console.log(this)
+    ev.preventDefault();
+
+    $.ajax(this.href)
+    .done(function(msg) {
+      if (msg.action === 'like') {
+        $(ev.target).parent().parent().children().toggleClass("hidden-button");
+        $(ev.target).parent().addClass("hidden-button");
+        $(".current-user-icon.idea-"+msg.idea_id).toggleClass("hidden-icon");
+      } else {
+        $(ev.target).parent().parent().children().toggleClass("hidden-button");
+        $(ev.target).parent().addClass("hidden-button");
+        $(".current-user-icon.idea-"+msg.idea_id).addClass("hidden-icon");
+      }
+    })
+    .fail(function(msg) {
+      alert("しっぱいしました reloadしてね")
+    });
+  })
+});

app/assets/stylesheets/application.css

@@ -12,3 +12,10 @@
  *= require bootstrap
  *= require_tree .
  */
+
+.hidden-icon {
+  display: none;
+}
+.hidden-button {
+  display: none;
+}

app/controllers/ideas_controller.rb

@@ -18,4 +18,24 @@ def create
       render 'welcome/index'
     end
   end
+
+  def like
+    idea = Idea.find(params[:idea_id])
+    if current_user.like(idea)
+      render :json => {action: 'like', idea_id: idea.id}, :status => 200
+    else
+      render :text => 'ng', :status => 500
+    end
+  end
+
+  def unlike
+    idea = Idea.find(params[:idea_id])
+    like = Like.where(idea_id: idea.id, user_id: current_user.id).first
+    if like and like.unlike
+      render :json => {action: 'unlike', idea_id: idea.id}, :status => 200
+    else
+      render :text => 'ng', :status => 500
+    end
+  end
+
 end

app/helpers/application_helper.rb

@@ -1,2 +1,38 @@
 module ApplicationHelper
+  def like_button(idea)
+    return nil unless logged_in?
+    like_flag = current_user.like?(idea)
+
+    buttons = content_tag(:button, class: "#{(like_flag) ? '' : 'hidden-button'}") do
+        link_to "unlike", unlike_path(idea_id: idea.id), class: "like"
+      end
+    buttons << content_tag(:button, class: "#{(like_flag) ? 'hidden-button' : ''}") do
+        link_to "like", like_path(idea_id: idea.id), class: "like"
+      end
+    content_tag :div do
+      buttons
+    end
+  end
+
+  def likes_list(idea)
+    users = idea.likes.map(&:user)
+    if logged_in?
+      users.reject!{|u| u == current_user}
+      like_now = current_user.like?(idea)
+    end
+    users_icon(users, like_now, "idea-#{idea.id}")
+  end
+
+  def users_icon(users, current_user_show, klass = "")
+    content_tag :div, :class => 'user-icon' do
+      html = ""
+      users.each do |user|
+        html << image_tag(user.image_url, width: 30, height: 30, alt: user.nickname, title: user.nickname)
+      end
+      if logged_in?
+        html << image_tag(current_user.image_url, width: 30, height: 30, alt: current_user.nickname, title: current_user.nickname, class: "#{klass} current-user-icon #{(current_user_show) ? '' : 'hidden-icon'}")
+      end
+      html.html_safe
+    end
+  end
 end

app/models/idea.rb

@@ -1,5 +1,6 @@
 class Idea < ActiveRecord::Base
   has_many :comments
+  has_many :likes
   belongs_to :user
 
   validates :title, length: { maximum: 100 }, presence: true

app/models/like.rb

@@ -0,0 +1,25 @@
+class Like < ActiveRecord::Base
+  default_scope -> {where(:live => true)}
+  belongs_to :user
+  belongs_to :idea
+
+  validate :idea, uniqueness: { scope: :user }
+
+  class << self
+    def create_with_user_and_idea(user, idea)
+      like = self.new(user_id: user.id, idea_id: idea.id)
+      like.save
+      like
+    end
+  end
+
+  def unlike
+    self.live = false
+    self.save
+  end
+
+  def relike
+    self.live = true
+    self.save
+  end
+end

app/models/user.rb

@@ -12,4 +12,16 @@ def self.find_or_create_from_auth_hash(auth_hash)
       user.image_url = image_url
     end
   end
+
+  def like(idea)
+    like = Like.unscoped.find_or_create_by(user_id: self.id, idea_id: idea.id)
+    if like and like.updated_at != like.created_at
+      like.relike
+    end
+    like
+  end
+
+  def like?(idea)
+    (Like.where(user_id: self.id, idea_id: idea.id).count >= 1)
+  end
 end

app/views/ideas/show.html.haml

@@ -1,5 +1,7 @@
 %h1
   = @idea.title
+= likes_list(@idea)
+= like_button(@idea)
 
 %hr
 

app/views/welcome/index.html.haml

@@ -29,3 +29,7 @@
           = idea.title
         - else
           = idea.title
+      %p
+        %span ↑
+        = likes_list(idea)
+        = like_button(idea)

config/routes.rb

@@ -3,6 +3,8 @@
   get '/auth/:provider/callback' => 'sessions#create'
   get '/auth/failure' => 'sessions#failure'
   get '/logout' => 'sessions#destroy', as: :logout
+  get '/like' => 'ideas#like', as: :like
+  get '/unlike' => 'ideas#unlike', as: :unlike
 
   resources :ideas, only: [:show, :create] do
     resources :comments, only: :create

db/migrate/20140520052025_create_likes.rb

@@ -0,0 +1,15 @@
+class CreateLikes < ActiveRecord::Migration
+  def change
+    create_table :likes do |t|
+
+      t.references :idea, :null => false
+      t.references :user, :null => false
+      t.boolean    :live, :null => false, :default  => true
+      t.timestamps
+    end
+
+    add_index :likes, :idea_id
+    add_index :likes, :user_id
+    add_index :likes, [:idea_id, :user_id], :unique => true
+  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: 20140427143623) do
+ActiveRecord::Schema.define(version: 20140520052025) do
 
   create_table "comments", force: true do |t|
     t.integer  "idea_id"
@@ -33,6 +33,18 @@
 
   add_index "ideas", ["user_id"], name: "index_ideas_on_user_id"
 
+  create_table "likes", force: true do |t|
+    t.integer  "idea_id",                   null: false
+    t.integer  "user_id",                   null: false
+    t.boolean  "live",       default: true, null: false
+    t.datetime "created_at"
+    t.datetime "updated_at"
+  end
+
+  add_index "likes", ["idea_id", "user_id"], name: "index_likes_on_idea_id_and_user_id", unique: true
+  add_index "likes", ["idea_id"], name: "index_likes_on_idea_id"
+  add_index "likes", ["user_id"], name: "index_likes_on_user_id"
+
   create_table "users", force: true do |t|
     t.string   "provider",   null: false
     t.string   "uid",        null: false

spec/factories/likes.rb

@@ -0,0 +1,6 @@
+# Read about factories at https://github.com/thoughtbot/factory_girl
+
+FactoryGirl.define do
+  factory :like do
+  end
+end

spec/models/like_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+describe Like do
+
+  describe "relations" do
+    it { should belong_to(:user) }
+    it { should belong_to(:idea) }
+  end
+
+  describe "#create_with_user_and_idea" do
+    before do
+      @user = build(:user)
+      @idea = build(:idea)
+    end
+
+    it "return created instance" do
+      expect(Like.create_with_user_and_idea(@user, @idea).class).to eq(Like)
+    end
+  end
+
+end