Add permalink to categories and scope articles

Author: viseztrance

app/controllers/articles_controller.rb

@@ -44,7 +44,11 @@ def destroy
   private
 
   def set_article
-    @article = Article.find_by!(permalink: params[:id])
+    @article = Article.find_by!(permalink: params[:id], category_id: category)
+  end
+
+  def category
+    Category.find_by(permalink: params[:category_id])
   end
 
   def article_params

app/models/article.rb

@@ -1,34 +1,9 @@
 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]
+  include Permalinkable
 
-    if count > 0
-      new_permalink += "-#{count}"
-    end
+  self.permalink_scope = "category_id"
 
-    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
+  belongs_to :category
 
-  def set_permalink
-    if regenerate_permalink.to_i > 0 || (new_record? && !permalink?)
-      self.permalink = generate_permalink
-    end
-  end
+  validates :title, :content, :category, presence: true
 end

app/models/category.rb

@@ -1,2 +1,5 @@
 class Category < ApplicationRecord
+  include Permalinkable
+
+  self.permalink_column = "name"
 end

app/models/concerns/permalinkable.rb

@@ -0,0 +1,42 @@
+module Permalinkable
+  extend ActiveSupport::Concern
+
+  included do
+    cattr_accessor :permalink_column, default: "title"
+    cattr_accessor :permalink_scope
+    attr_accessor :regenerate_permalink
+    before_save :set_permalink
+  end
+
+  def generate_permalink(count = 0)
+    column_value = attributes.fetch(self.class.permalink_column)
+    new_permalink = column_value.parameterize[0..49]
+
+    if count > 0
+      new_permalink += "-#{count}"
+    end
+
+    if scoped_permalink_entries.find_by(permalink: new_permalink)
+      new_permalink = generate_permalink(count + 1)
+    end
+
+    new_permalink
+  end
+
+  def to_param
+    permalink
+  end
+
+  private
+
+  def scoped_permalink_entries
+    context = attributes.slice(self.class.permalink_scope)
+    self.class.where(context).where.not(id: id)
+  end
+
+  def set_permalink
+    if regenerate_permalink.to_i > 0 || (new_record? && !permalink?)
+      self.permalink = generate_permalink
+    end
+  end
+end

db/migrate/20191001191142_add_permalink_to_categories.rb

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

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_09_17_195150) do
+ActiveRecord::Schema.define(version: 2019_10_01_191142) do
 
   create_table "articles", force: :cascade do |t|
     t.string "title"
@@ -27,6 +27,8 @@
     t.string "name"
     t.datetime "created_at", precision: 6, null: false
     t.datetime "updated_at", precision: 6, null: false
+    t.string "permalink"
+    t.index ["permalink"], name: "index_categories_on_permalink"
   end
 
   add_foreign_key "articles", "categories"

spec/controllers/articles_controller_spec.rb

@@ -14,6 +14,19 @@
       expect(response.status).to eql(200)
     end
 
+    context "without correct category" do
+      subject(:perform_request) {
+        get :show, params: { id: "my-permalink", category_id: other_category }
+      }
+
+      let(:other_category) { FactoryBot.create(:category) }
+
+      it "raises error" do
+        expect { perform_request }
+          .to raise_error(ActiveRecord::RecordNotFound)
+      end
+    end
+
     context "without correct permalink" do
       subject(:perform_request) {
         get :show, params: { id: "wrong-permalink", category_id: category }

spec/models/article_spec.rb

@@ -4,8 +4,9 @@
   describe "#generate_permalink" do
     subject { article.generate_permalink }
 
+    let(:category) { FactoryBot.create(:category) }
     let(:article) {
-      FactoryBot.build_stubbed(:article, title: "Hello world!")
+      FactoryBot.build(:article, title: "Hello world!", category: category)
     }
 
     it { is_expected.to eql("hello-world") }
@@ -20,15 +21,23 @@
 
     context "with existing article having the same title" do
       before do
-        FactoryBot.create(:article, title: "Hello world!")
+        FactoryBot.create(:article, title: "Hello world!", category: category)
       end
 
       it { is_expected.to eql("hello-world-1") }
     end
 
+    context "with existing article having the same title and different category" do
+      before do
+        FactoryBot.create(:article, title: "Hello world!")
+      end
+
+      it { is_expected.to eql("hello-world") }
+    end
+
     context "with multiple existing articles having the same title" do
       before do
-        FactoryBot.create_list(:article, 3, title: "Hello world!")
+        FactoryBot.create_list(:article, 3, title: "Hello world!", category: category)
       end
 
       it { is_expected.to eql("hello-world-3") }

spec/models/category_spec.rb

@@ -0,0 +1,13 @@
+require 'rails_helper'
+
+RSpec.describe Category do
+  describe "#save" do
+    subject(:save) { category.save }
+
+    let(:category) { FactoryBot.build(:category, name: "Politics!") }
+
+    it "sets a permalink" do
+      expect { save }.to change { category.permalink }.to("politics")
+    end
+  end
+end