[RUBY] [Rails] Comment function implementation procedure memo

At the beginning

A memorandum about the ability to comment on posts


environment Ruby 2.6 series Rails 5.2 series

Library  devise  Slim

__ Rails app template for the above environment __ Procedure to set up Rails application and install devise and Slim

__ ↓ Image after implementation of comment function ↓ __ ezgif.com-video-to-gif (1).gif


1. Model design

スクリーンショット 2020-06-09 21.23.55.png

-User and Post are one-to-many relationships where User has many Posts. -User has many comments, and Post also has many comments. Many-to-many relationship. -Create an intermediate table and add a comment_content column to store the comment owner (user_id), the post that owns the comment (post_id), and the content of the comment for each record.

2. Model creation

$ rails g devise User

$ rails g model Post post_content:string user:references 
$ rails g model Comment comment_content:string user:references post:references

-Since devise is installed, the User model is created with the devise command.

-If you specify references, a foreign key (required) will be automatically set in the migration file.

3. Confirm and associate models and migrations.

users table

class DeviseCreateUsers < ActiveRecord::Migration[5.2] def change create_table :users do |t| ## Database authenticatable t.string :email, null: false, default: "" t.string :encrypted_password, null: false, default: "" . . # . . add_index :users, :email, unique: true add_index :users, :reset_password_token, unique: true end end

 > User model

class User < ApplicationRecord
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable
  has_many :posts, dependent: :destroy
  has_many :comments  #User.You can get user-owned comments with comments.

posts table

class CreatePosts < ActiveRecord::Migration[5.2] def change create_table :posts do |t| t.text :post_content t.references :user, foreign_key: true   t.timestamps end end end

 > Post model

class Post < ApplicationRecord
  belongs_to :user
  has_many :comments, dependent: :destroy  #Post.You can get the comments w owned by the post with comments.

comments table

class CreateComments < ActiveRecord::Migration[5.2] def change create_table :comments do |t| t.text :comment_content t.references :user, foreign_key: true t.references :post, foreign_key: true   t.timestamps end end end

 > Comment model

class Comment < ApplicationRecord
  belongs_to :user  #Comment.Get the owner of the comment with user
  belongs_to :post  #Comment.Get the post with that comment on post

4. Create controller

$ rails g controller posts index show
$ rails g controller comments

4-1. Creating a posts controller


class PostsController < ApplicationController

  #Check the login status of the user. The index can be viewed without logging in.
  before_action :authenticate_user!, only: [:show, :create]

  def index
    @posts = current_user.posts.all  #Get all to display post list
    @post = current_user.posts.new   #Since a new post is made on the post list screen, get the Post object for the form parameter.

  def show
    @post = Post.find(params[:id])
    @comments = @post.comments  #Get all comments associated with post details
    @comment = current_user.comments.new  #Since the comment is posted on the post details screen, get the Comment object for the form parameter.

  def create
    @post = current_user.posts.new(post_params)
    if @post.save
      redirect_back(fallback_location: root_path)  #After sending the comment, redirect to the previous page.
      redirect_back(fallback_location: root_path)  #Same as above

  def post_params

-The id of the logged-in user is stored in all Posts and Comments acquired as current_user. It can be used because the association made in the model file and devise were introduced.

4-2.comments Creating a controller


class CommentsController < ApplicationController

  def create
    @comment = current_user.comments.new(comment_params)
    if @comment.save
      redirect_back(fallback_location: root_path)  #After sending the comment, redirect to the previous page.
      redirect_back(fallback_location: root_path)  #Same as above

  def comment_params
    params.require(:comment).permit(:comment_content, :post_id)  #post in form_Send id parameter and post to comment_It is necessary to store the id.

5. Create view

5-1. Creating a post list view


h2 post

= form_with model: @post do |f|
   = f.text_area :post_content, placeholder: 'Text'
   = f.submit

h2 post list

- @posts.each do |post|
   = link_to post.post_content, post

= link_to 'home', root_path

5-2. Creating a post details screen view (also create a comment posting form and a view of the comment list)


h2 post details

= @post.post_content

h2 make a comment

= form_with(model:[@post, @comment], method: :post) do |f|
  = f.text_area :comment_content
  = f.hidden_field :post_id, value: @post.id
  = f.submit 'To comment'

h2 comment list

- @comments.each do |comment|
  = comment.comment_content  #The content of the comment is displayed

= link_to 'home', root_path

· ``` Model: [@post, @comment]` `` Description for accessing nested routing. If you don't give two arguments properly, it will not be sent properly.

-In the hidden input field, the value post.id is sent with the parameter post_id. To store in the post_id of the Comment table.

6. Create a routing


Rails.application.routes.draw do
  devise_for :users  #Routing for user authentication created by devise

  root to: 'posts#index'  #Home screen is set to post list screen

  resources :posts do  #routing to posts controller
    resources :comments, only: [:create]  #comments Routing to controller

-By nesting comments resources within posts resources, it is convenient to specify a path such as post_comments_path.

This completes the implementation of the comment function.

Articles that I used as a reference

[Let's make a comment function with Rails](https://qiita.com/nojinoji/items/2034764897c6e91ef982#%E3%83%AB%E3%83%BC%E3%83%86%E3%82%A3% E3% 83% B3% E3% 82% B0% E3% 81% AE% E4% BD% 9C% E6% 88% 90-1)

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