Ruby on Rails: Add Post Comments scaffold

app/controllers/comments_controller.rb

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+class CommentsController < ApplicationController
+  before_action :set_comment, only: %i[ show edit update destroy ]
+
+  # GET /comments or /comments.json
+  def index
+    @comments = Comment.alll
+  end
+
+  # GET /comments/1 or /comments/1.json
+  def show
+  end
+
+  # GET /comments/new
+  def new
+    @comment = Comment.new
+  end
+
+  # GET /comments/1/edit
+  def edit
+  end
+
+  # POST /comments or /comments.json
+  def create
+    @comment = Comment.new(comment_params)
+
+    respond_to do |format|
+      if @comment.save
+        format.html { redirect_to comment_url(@comment), notice: "Comment was successfully created." }
+        format.json { render :show, status: :created, location: @comment }
+      else
+        format.html { render :new, status: :unprocessable_entity }
+        format.json { render json: @comment.errors, status: :unprocessable_entity }
+      end
+    end
+  end
+
+  # PATCH/PUT /comments/1 or /comments/1.json
+  def update
+    respond_to do |format|
+      if @comment.update(comment_params)
+        format.html { redirect_to comment_url(@comment), notice: "Comment was successfully updated." }
+        format.json { render :show, status: :ok, location: @comment }
+      else
+        format.html { render :edit, status: :unprocessable_entity }
+        format.json { render json: @comment.errors, status: :unprocessable_entity }
+      end
+    end
+  end
+
+  # DELETE /comments/1 or /comments/1.json
+  def destroy
+    @comment.destroy!
+
+    respond_to do |format|
+      format.html { redirect_to comments_url, notice: "Comment was successfully destroyed." }
+      format.json { head :no_content }
+    end
+  end
+
+  private
+    # Use callbacks to share common setup or constraints between actions.
+    def set_comment
+      @comment = Comment.find(params[:id])
+    end
+
+    # Only allow a list of trusted parameters through.
+    def comment_params
+      params.require(:comment).permit(:post_id)
+    end
+end

app/helpers/comments_helper.rb

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+module CommentsHelper
+end

app/models/comment.rb

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+class Comment < ApplicationRecord
+  belongs_to :post
+end

app/views/comments/_comment.html.erb

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+<div id="<%= dom_id comment %>">
+  <p>
+    <strong>Post:</strong>
+    <%= comment.post_id %>
+  </p>
+
+</div>

app/views/comments/_comment.json.jbuilder

@@ -0,0 +1,2 @@
+json.extract! comment, :id, :post_id, :created_at, :updated_at
+json.url comment_url(comment, format: :json)

app/views/comments/_form.html.erb

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+<%= form_with(model: comment) do |form| %>
+  <% if comment.errors.any? %>
+    <div style="color: red">
+      <h2><%= pluralize(comment.errors.count, "error") %> prohibited this comment from being saved:</h2>
+
+      <ul>
+        <% comment.errors.each do |error| %>
+          <li><%= error.full_message %></li>
+        <% end %>
+      </ul>
+    </div>
+  <% end %>
+
+  <div>
+    <%= form.label :post_id, style: "display: block" %>
+    <%= form.text_field :post_id %>
+  </div>
+
+  <div>
+    <%= form.submit %>
+  </div>
+<% end %>

app/views/comments/edit.html.erb

@@ -0,0 +1,10 @@
+<h1>Editing comment</h1>
+
+<%= render "form", comment: @comment %>
+
+<br>
+
+<div>
+  <%= link_to "Show this comment", @comment %> |
+  <%= link_to "Back to comments", comments_path %>
+</div>

app/views/comments/index.html.erb

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+<p style="color: green"><%= notice %></p>
+
+<h1>Comments</h1>
+
+<div id="comments">
+  <% @comments.each do |comment| %>
+    <%= render comment %>
+    <p>
+      <%= link_to "Show this comment", comment %>
+    </p>
+  <% end %>
+</div>
+
+<%= link_to "New comment", new_comment_path %>

app/views/comments/index.json.jbuilder

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+json.array! @comments, partial: "comments/comment", as: :comment

app/views/comments/new.html.erb

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+<h1>New comment</h1>
+
+<%= render "form", comment: @comment %>
+
+<br>
+
+<div>
+  <%= link_to "Back to comments", comments_path %>
+</div>

app/views/comments/show.html.erb

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+<p style="color: green"><%= notice %></p>
+
+<%= render @comment %>
+
+<div>
+  <%= link_to "Edit this comment", edit_comment_path(@comment) %> |
+  <%= link_to "Back to comments", comments_path %>
+
+  <%= button_to "Destroy this comment", @comment, method: :delete %>
+</div>

app/views/comments/show.json.jbuilder

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+json.partial! "comments/comment", comment: @comment

config/routes.rb

@@ -1,3 +1,4 @@
 Rails.application.routes.draw do
+  resources :comments
   root "hello#index"
 end

db/migrate/20240523083551_create_comments.rb

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+class CreateComments < ActiveRecord::Migration[7.1]
+  def change
+    create_table :comments do |t|
+      t.references :post, null: false, foreign_key: true
+
+      t.timestamps
+    end
+  end
+end

test/controllers/comments_controller_test.rb

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+require "test_helper"
+
+class CommentsControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    @comment = comments(:one)
+  end
+
+  test "should get index" do
+    get comments_url
+    assert_response :success
+  end
+
+  test "should get new" do
+    get new_comment_url
+    assert_response :success
+  end
+
+  test "should create comment" do
+    assert_difference("Comment.count") do
+      post comments_url, params: { comment: { post_id: @comment.post_id } }
+    end
+
+    assert_redirected_to comment_url(Comment.last)
+  end
+
+  test "should show comment" do
+    get comment_url(@comment)
+    assert_response :success
+  end
+
+  test "should get edit" do
+    get edit_comment_url(@comment)
+    assert_response :success
+  end
+
+  test "should update comment" do
+    patch comment_url(@comment), params: { comment: { post_id: @comment.post_id } }
+    assert_redirected_to comment_url(@comment)
+  end
+
+  test "should destroy comment" do
+    assert_difference("Comment.count", -1) do
+      delete comment_url(@comment)
+    end
+
+    assert_redirected_to comments_url
+  end
+end

test/fixtures/comments.yml

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+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+one:
+  post: one
+
+two:
+  post: two

test/models/comment_test.rb

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+require "test_helper"
+
+class CommentTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end

test/system/comments_test.rb

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+require "application_system_test_case"
+
+class CommentsTest < ApplicationSystemTestCase
+  setup do
+    @comment = comments(:one)
+  end
+
+  test "visiting the index" do
+    visit comments_url
+    assert_selector "h1", text: "Comments"
+  end
+
+  test "should create comment" do
+    visit comments_url
+    click_on "New comment"
+
+    fill_in "Post", with: @comment.post_id
+    click_on "Create Comment"
+
+    assert_text "Comment was successfully created"
+    click_on "Back"
+  end
+
+  test "should update Comment" do
+    visit comment_url(@comment)
+    click_on "Edit this comment", match: :first
+
+    fill_in "Post", with: @comment.post_id
+    click_on "Update Comment"
+
+    assert_text "Comment was successfully updated"
+    click_on "Back"
+  end
+
+  test "should destroy Comment" do
+    visit comment_url(@comment)
+    click_on "Destroy this comment", match: :first
+
+    assert_text "Comment was successfully destroyed"
+  end
+end