[#10] Setup vote model which belongs to a user a votable (which can e…

…ither be an article or comment). Added upvote/downvote methods in article controller.

app/controllers/articles_controller.rb

@@ -1,15 +1,25 @@
 class ArticlesController < ApplicationController
   before_action :authorized, only: [:new, :create]
+  before_action :set_article, only: [:show, :upvote, :downvote]
   def index
     @articles = Article.order(created_at: :desc).page(params[:page]).per(20)
   end
 
   def show
-    @article = Article.find(params[:id])
     @comments = @article.comments.without_parent.order(created_at: :desc)
     @comment = Comment.new
   end
 
+  def upvote
+    vote(1)
+    redirect_to @article
+  end
+
+  def downvote
+    vote(-1)
+    redirect_to @article
+  end
+
   def new
     @article = Article.new
   end
@@ -27,7 +37,20 @@ def create
 
   private
 
+  def set_article
+    @article = Article.find(params[:id])
+  end
+
   def article_params
     params.require(:article).permit(:title, :link)
   end
+
+  def vote(value)
+    @vote = @article.votes.find_or_initialize_by(user: current_user)
+    if @vote.value == value
+      @vote.update(value: 0)
+    else
+      @vote.update(value: value)
+    end
+  end
 end

app/models/article.rb

@@ -8,6 +8,12 @@
 class Article < ApplicationRecord
   belongs_to :user
   has_many :comments
+  has_many :votes, as: :votable
+
   validates :title, presence: true
   validates :link, presence: true
+
+  def score
+    votes.sum(:value)
+  end
 end

app/models/comment.rb

@@ -2,6 +2,8 @@ class Comment < ApplicationRecord
   belongs_to :article
   belongs_to :user
   validates :text, presence: true
+  has_many :votes, as: :votable
+
 
   belongs_to :parent, class_name: "Comment", optional: true
   has_many :replies, class_name: "Comment", foreign_key: :parent_id, dependent: :destroy

app/models/user.rb

@@ -2,6 +2,7 @@ class User < ApplicationRecord
   has_secure_password
   has_many :articles
   has_many :comments
+  has_many :votes
 
   validates :name, presence: true, uniqueness: true
   validates :email, presence: true, uniqueness: true, format: {with: URI::MailTo::EMAIL_REGEXP, message: "must be a valid email address"}

app/models/vote.rb

@@ -0,0 +1,6 @@
+class Vote < ApplicationRecord
+  belongs_to :user
+  belongs_to :votable, polymorphic: true
+
+  validates :value, inclusion: {in: [-1, 0, 1]}
+end

config/routes.rb

@@ -2,6 +2,10 @@
   root "articles#index"
   resources :articles do
     resources :comments, only: [:create, :show]
+    member do
+      post "upvote"
+      post "downvote"
+    end
   end
   resources :users, only: [:create, :show]
   get "/signup", to: "users#new"

db/migrate/20240626175659_create_votes.rb

@@ -0,0 +1,11 @@
+class CreateVotes < ActiveRecord::Migration[7.1]
+  def change
+    create_table :votes do |t|
+      t.references :user, null: false, foreign_key: true
+      t.references :votable, polymorphic: true, null: false
+      t.integer :value
+
+      t.timestamps
+    end
+  end
+end

spec/controllers/articles_controller_spec.rb

@@ -38,5 +38,38 @@
         Article.count
       }.by(1)
     end
+
+    describe "POST #upvote" do
+      it "sets vote value to 1 if user has not voted" do
+        expect {
+          post :upvote, params: {id: article.id}
+        }.to change { article.votes.count }.by(1)
+        expect(article.reload.votes.last.value).to eq(1)
+      end
+
+      it "sets vote value to 0 if user has already upvoted" do
+        create(:vote, votable: article, user: user, value: 1)
+        expect {
+          post :upvote, params: {id: article.id}
+        }.not_to change { article.votes.count }
+        expect(article.reload.votes.last.value).to eq(0)
+      end
+    end
+
+    describe "POST #downvote" do
+      it "sets vote value to -1 if user has not already downvoted" do
+        expect {
+          post :downvote, params: {id: article.id}
+        }.to change { article.votes.count }.by(1)
+        expect(article.reload.votes.last.value).to eq(-1)
+      end
+      it "sets vote value to 0 if user has already downvoted" do
+        create(:vote, votable: article, user: user, value: -1)
+        expect {
+          post :downvote, params: {id: article.id}
+        }.not_to change { article.votes.count }
+        expect(article.reload.votes.last.value).to eq(0)
+      end
+    end
   end
 end

spec/factories/votes.rb

@@ -0,0 +1,7 @@
+FactoryBot.define do
+  factory :vote do
+    association :user, factory: :user
+    association :votable, factory: :article
+    value { 0 }
+  end
+end

spec/models/vote_spec.rb

@@ -0,0 +1,37 @@
+require "rails_helper"
+
+RSpec.describe Vote, type: :model do
+  let(:user) { create(:user) }
+  let(:article) { create(:article, user: user) }
+  let(:comment) { create(:comment, article: article, user: user) }
+  let(:vote) {create(:vote, votable: article, user: user)}
+  let(:comment_vote) {create(:vote, votable: comment, user: user)}
+
+  it "should be valid with valid attributes" do
+    expect(vote.valid?).to be(true)
+  end
+
+  it "should be valid with comment as votable" do
+    expect(comment_vote.valid?).to be(true)
+  end
+
+  it "value should be present" do
+    vote.value = nil
+    expect(vote.valid?).to be(false)
+  end
+
+  it "should not be valid with a value other than -1, 0, or 1" do
+    vote.value = 2
+    expect(vote.valid?).to be(false)
+  end
+
+  it "should belong to a user" do
+    vote.user = nil
+    expect(vote.valid?).to be(false)
+  end
+
+  it "should belong to a votable" do
+    vote.votable = nil
+    expect(vote.valid?).to be(false)
+  end
+end