[RUBY] How to implement a like feature in Rails

I will show you how to implement the like function in Rails. The completed system looks like the following.

environment

• Ruby 2.5.7
• Rails 5.2.4

Premise

--The login function by devise can be implemented. --The user table is "users", the article table is "posts", and the likes intermediate table is "likes". --Add title to the posts column

Added Like model

$ rails g model like user_id:integer post_id:integer

$ rails db:migrate

Set up an association

Describe the following for each and set the association.

like.rb

  belongs_to :user
  belongs_to :post

user.rb

  has_many :likes, dependent: :destroy

post.rb

  has_many :likes, dependent: :destroy

Set up routing

routes.rb

  resources :posts, shallow: true do
    resources :likes, only: [:create, :destroy]
  end

Create preferred_by? method

post.rb

  def liked_by?(user)
    likes.where(user_id: user.id).exists?
  end

Description of controller

likes_controller.rb

  def create
    like = Like.new(user_id: current_user.id, post_id: params[:post_id])
    @post = like.post
    like.save
    redirect_back(fallback_location: posts_path)
  end

  def destroy
    like = Like.find(params[:id])
    @post = like.post
    like.destroy
    redirect_back(fallback_location: posts_path)
  end

Introduced Bootstrap

Gemfile

gem 'bootstrap-sass', '~> 3.3.6'
gem 'jquery-rails'

$ bundle install

Rename application.css to application.scss

$ mv app/assets/stylesheets/application.css app/assets/stylesheets/application.scss

Load Bootstrap into scss

Write the following at the bottom of application.scss

application.scss

@import "bootstrap-sprockets";
@import "bootstrap";

Edit application.js

The following part of application.js

application.js

//= require rails-ujs
//= require turbolinks
//= require_tree .

From

application.js

//= require rails-ujs
//= require jquery
//= require bootstrap-sprockets
//= require_tree .

Rewrite to.

Edit index.html.erb

html:index.html.erb

<div class="container">
  <h1>List of articles</h1>
  <table class="table">
    <% @posts.each do |post| %>
      <tr>
        <td><%= post.title %></td>
        <td>
          <% if post.liked_by?(current_user) %>
            <% like = Like.find_by(user_id: current_user.id, post_id: post.id) %>
            <%= link_to like_path(like), method: :delete do %>
              <span class="glyphicon glyphicon-heart" aria-hidden="true" style="color: red;">
              <span><%= post.likes.count %></span>
            <% end %>
          <% else %>
            <%= link_to post_likes_path(post), method: :post do %>
              <span class="glyphicon glyphicon-heart" aria-hidden="true" style="color: gray;">
              <span><%= post.likes.count %></span>
            <% end %>
          <% end %>
        </td>
      </tr>
    <% end %>
  </table>
</div>

That's all there is to it.

Reference article

https://qiita.com/soehina/items/a68ab66da3ea1d260301