いいね機能を利用したユーザー評価

$ rails g model like post:references user:references
$ rails db:migrate

class User < ApplicationRecord
# 中略
  has_many :likes
end

class Idea < ApplicationRecord
# 中略
  has_many :likes
end

class Like < ApplicationRecord
  belongs_to :user
  belongs_to :idea
end

$ rails g controller likes

class LikesController < ApplicationController
  def create
    Like.create(user_id: current_user.id,idea_id: params[:idea_id])
    redirect_to root_path
  end
end

Rails.application.routes.draw do
# 中略
  resources :ideas,except: :index do
    resources :likes, only: :create
    # 中略
  end
# 中略
end

<!--中略-->
<div>
　<%= button_to 'Good', idea_likes_path(@idea), class:'good-btn' %>
</div>
<!--中略-->

class UsersController < ApplicationController
  def show
    @user = User.find(params[:id])
    @user_ideas= @user.ideas
  end
end

class UsersController < ApplicationController
def show
    @user = User.find(params[:id])
    @user_ideas= @user.ideas
    #　Goodの合計を計算する
    @likes_count = 0
    @user_ideas.each do |idea|
      @likes_count += idea.likes.count
    end

　　#　Badの合計を計算する
    @dislikes_count = 0
    @user_ideas.each do |idea|
      @dislikes_count += idea.dislikes.count
    end
  end
end

<div class="good-button"><%= @likes_count%></div>　   <!--Good評価-->
<div class="bad-button2"><%= @dislikes_count%></div>  <!--Bad評価-->