Add permalink to article

Author: viseztrance

app/controllers/articles_controller.rb

@@ -42,10 +42,12 @@ def destroy
   private
 
   def set_article
-    @article = Article.find(params[:id])
+    @article = Article.find_by!(permalink: params[:id])
   end
 
   def article_params
-    params.require(:article).permit(:title, :content, :category_id)
+    params
+      .require(:article)
+      .permit(:title, :content, :category_id, :regenerate_permalink)
   end
 end

app/models/article.rb

@@ -2,4 +2,33 @@ class Article < ApplicationRecord
   belongs_to :category
 
   validates :title, :content, :category, presence: true
+
+  attr_accessor :regenerate_permalink
+  before_save :set_permalink
+
+  def generate_permalink(count = 0)
+    new_permalink = title.parameterize[0..49]
+
+    if count > 0
+      new_permalink += "-#{count}"
+    end
+
+    if Article.where.not(id: id).find_by(permalink: new_permalink)
+      new_permalink = generate_permalink(count + 1)
+    end
+
+    new_permalink
+  end
+
+  def to_param
+    permalink
+  end
+
+  private
+
+  def set_permalink
+    if regenerate_permalink.to_i > 0 || (new_record? && !permalink?)
+      self.permalink = generate_permalink
+    end
+  end
 end

app/views/articles/_form.html.erb

@@ -11,5 +11,11 @@
 
   <p><%= f.text_area :content, placeholder: "Content" %></p>
   <p><%= f.collection_select :category_id, Category.all, :id, :name %></p>
+  <% if f.object.persisted? %>
+    <p>
+      <%= f.check_box :regenerate_permalink %>
+      <%= f.label :regenerate_permalink %>
+    </p>
+  <% end %>
   <p><%= f.submit "Save" %></p>
 <% end %>

db/migrate/20190917195150_add_permalink_to_article.rb

@@ -0,0 +1,6 @@
+class AddPermalinkToArticle < ActiveRecord::Migration[6.0]
+  def change
+    add_column :articles, :permalink, :string
+    add_index :articles, :permalink
+  end
+end

db/schema.rb

@@ -10,15 +10,17 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_09_03_210440) do
+ActiveRecord::Schema.define(version: 2019_09_17_195150) do
 
   create_table "articles", force: :cascade do |t|
     t.string "title"
     t.text "content"
     t.integer "category_id", null: false
     t.datetime "created_at", precision: 6, null: false
     t.datetime "updated_at", precision: 6, null: false
+    t.string "permalink"
     t.index ["category_id"], name: "index_articles_on_category_id"
+    t.index ["permalink"], name: "index_articles_on_permalink"
   end
 
   create_table "categories", force: :cascade do |t|

spec/controllers/articles_controller_spec.rb

@@ -0,0 +1,26 @@
+require 'rails_helper'
+
+RSpec.describe ArticlesController do
+  describe "#show" do
+    before do
+      FactoryBot.create(:article, permalink: "my-permalink")
+    end
+
+    it "renders successfully" do
+      get :show, params: { id: "my-permalink" }
+
+      expect(response.status).to eql(200)
+    end
+
+    context "without correct permalink" do
+      subject(:perform_request) {
+        get :show, params: { id: "wrong-permalink" }
+      }
+
+      it "raises error" do
+        expect { perform_request }
+          .to raise_error(ActiveRecord::RecordNotFound)
+      end
+    end
+  end
+end

spec/models/article_spec.rb

@@ -0,0 +1,53 @@
+require 'rails_helper'
+
+RSpec.describe Article do
+  describe "#generate_permalink" do
+    subject { article.generate_permalink }
+
+    let(:article) {
+      FactoryBot.build_stubbed(:article, title: "Hello world!")
+    }
+
+    it { is_expected.to eql("hello-world") }
+
+    context "with a very long title" do
+      let(:article) {
+        FactoryBot.build_stubbed(:article, title: "x" * 200)
+      }
+
+      it { is_expected.to eql("x" * 50) }
+    end
+
+    context "with existing article having the same title" do
+      before do
+        FactoryBot.create(:article, title: "Hello world!")
+      end
+
+      it { is_expected.to eql("hello-world-1") }
+    end
+
+    context "with multiple existing articles having the same title" do
+      before do
+        FactoryBot.create_list(:article, 3, title: "Hello world!")
+      end
+
+      it { is_expected.to eql("hello-world-3") }
+    end
+  end
+
+  describe "#save" do
+    subject(:save) { article.save }
+
+    let(:article) { FactoryBot.build(:article) }
+
+    before do
+      allow(article)
+        .to receive(:generate_permalink).and_return("my-permalink")
+    end
+
+    it "sets permalink" do
+      expect { save }
+        .to change { article.permalink }.to("my-permalink")
+    end
+  end
+end