Make learning materials page CRUD using the Rails Admin gem

.rspec

@@ -0,0 +1 @@
+--require spec_helper

Gemfile

@@ -16,8 +16,6 @@ gem 'image_processing', '~> 1.2'
 gem 'jbuilder' # Build JSON APIs with ease [https://github.com/rails/jbuilder]
 gem 'jsbundling-rails' # Bundle and transpile JavaScript [https://github.com/rails/jsbundling-rails]
 gem 'mini_magick', '~> 4.12'
-# Motor Admin allows you to deploy a no-code admin panel for your application in less than a minute
-gem 'motor-admin', '~> 0.4.7'
 gem 'pg', '~> 1.1' # Use postgresql as the database for Active Record
 gem 'premailer-rails', '~> 1.12' # This gem is a drop in solution for styling HTML emails with CSS
 gem 'puma', '~> 5.0' # Use the Puma web server [https://github.com/puma/puma]
@@ -66,7 +64,11 @@ group :test do
   # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing]
   gem 'capybara'
   gem 'faker', '~> 3.1'
+  gem 'rspec-rails', '~> 6.1'
   gem 'selenium-webdriver'
   gem 'simplecov', require: false  # Code coverage analysis tool for ruby
   gem 'webdrivers'
 end
+
+gem 'rails_admin', '~> 3.1'
+gem 'sassc-rails'

Gemfile.lock

@@ -56,6 +56,10 @@ GEM
       globalid (>= 0.3.6)
     activemodel (7.0.3)
       activesupport (= 7.0.3)
+    activemodel-serializers-xml (1.0.2)
+      activemodel (> 5.x)
+      activesupport (> 5.x)
+      builder (~> 3.1)
     activerecord (7.0.3)
       activemodel (= 7.0.3)
       activesupport (= 7.0.3)
@@ -75,11 +79,7 @@ GEM
       public_suffix (>= 2.0.2, < 5.0)
     airbrussh (1.4.1)
       sshkit (>= 1.6.1, != 1.7.0)
-    ar_lazy_preload (1.1.2)
-      rails (>= 5.2)
     ast (2.4.2)
-    audited (5.3.2)
-      activerecord (>= 5.0, < 7.1)
     aws-eventstream (1.2.0)
     aws-partitions (1.721.0)
     aws-sdk-core (3.170.0)
@@ -149,19 +149,15 @@ GEM
       railties (>= 4.1.0)
       responders
       warden (~> 1.2.3)
+    diff-lcs (1.5.1)
     digest (3.1.0)
     docile (1.4.0)
     dockerfile-rails (1.2.5)
       rails
     erubi (1.10.0)
-    et-orbi (1.2.7)
-      tzinfo
     faker (3.1.0)
       i18n (>= 1.8.11, < 2)
     ffi (1.15.5)
-    fugit (1.8.1)
-      et-orbi (~> 1, >= 1.2.7)
-      raabro (~> 1.4)
     globalid (1.0.0)
       activesupport (>= 5.0)
     htmlentities (4.3.4)
@@ -180,6 +176,18 @@ GEM
     jsbundling-rails (1.0.2)
       railties (>= 6.0.0)
     json (2.6.3)
+    kaminari (1.2.2)
+      activesupport (>= 4.1.0)
+      kaminari-actionview (= 1.2.2)
+      kaminari-activerecord (= 1.2.2)
+      kaminari-core (= 1.2.2)
+    kaminari-actionview (1.2.2)
+      actionview
+      kaminari-core (= 1.2.2)
+    kaminari-activerecord (1.2.2)
+      activerecord
+      kaminari-core (= 1.2.2)
+    kaminari-core (1.2.2)
     launchy (2.5.0)
       addressable (~> 2.7)
     letter_opener (1.8.1)
@@ -195,13 +203,8 @@ GEM
     mini_magick (4.12.0)
     mini_mime (1.1.2)
     minitest (5.15.0)
-    motor-admin (0.4.7)
-      ar_lazy_preload (~> 1.0)
-      audited (~> 5.0)
-      cancancan (~> 3.0)
-      fugit (~> 1.0)
-      rails (>= 5.2)
     msgpack (1.5.2)
+    nested_form (0.3.2)
     net-imap (0.2.3)
       digest
       net-protocol
@@ -242,7 +245,6 @@ GEM
     public_suffix (4.0.7)
     puma (5.6.4)
       nio4r (~> 2.0)
-    raabro (1.4.0)
     racc (1.6.0)
     rack (2.2.3.1)
     rack-test (1.1.0)
@@ -266,6 +268,12 @@ GEM
       nokogiri (>= 1.6)
     rails-html-sanitizer (1.4.2)
       loofah (~> 2.3)
+    rails_admin (3.1.2)
+      activemodel-serializers-xml (>= 1.0)
+      kaminari (>= 0.14, < 2.0)
+      nested_form (~> 0.3)
+      rails (>= 6.0, < 8)
+      turbo-rails (~> 1.0)
     railties (7.0.3)
       actionpack (= 7.0.3)
       activesupport (= 7.0.3)
@@ -283,6 +291,23 @@ GEM
       actionpack (>= 5.0)
       railties (>= 5.0)
     rexml (3.2.5)
+    rspec-core (3.13.0)
+      rspec-support (~> 3.13.0)
+    rspec-expectations (3.13.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-mocks (3.13.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.13.0)
+    rspec-rails (6.1.2)
+      actionpack (>= 6.1)
+      activesupport (>= 6.1)
+      railties (>= 6.1)
+      rspec-core (~> 3.13)
+      rspec-expectations (~> 3.13)
+      rspec-mocks (~> 3.13)
+      rspec-support (~> 3.13)
+    rspec-support (3.13.1)
     rubocop (1.51.0)
       json (~> 2.3)
       parallel (~> 1.10)
@@ -307,6 +332,14 @@ GEM
       ffi (~> 1.12)
     ruby_http_client (3.5.5)
     rubyzip (2.3.2)
+    sassc (2.4.0)
+      ffi (~> 1.9)
+    sassc-rails (2.1.2)
+      railties (>= 4.0.0)
+      sassc (>= 2.0)
+      sprockets (> 3.0)
+      sprockets-rails
+      tilt
     selenium-webdriver (4.2.0)
       childprocess (>= 0.5, < 5.0)
       rexml (~> 3.2, >= 3.2.5)
@@ -346,6 +379,7 @@ GEM
       railties (>= 6.0.0)
     strscan (3.0.3)
     thor (1.2.1)
+    tilt (2.3.0)
     timeout (0.3.0)
     turbo-rails (1.1.1)
       actionpack (>= 6.0.0)
@@ -401,15 +435,17 @@ DEPENDENCIES
   jsbundling-rails
   letter_opener
   mini_magick (~> 4.12)
-  motor-admin (~> 0.4.7)
   pg (~> 1.1)
   premailer-rails (~> 1.12)
   puma (~> 5.0)
   rails (~> 7.0.3)
+  rails_admin (~> 3.1)
   redis (~> 4.0)
+  rspec-rails (~> 6.1)
   rubocop (~> 1.51.0)
   rubocop-performance (~> 1.18)
   rubocop-rails (~> 2.19.1)
+  sassc-rails
   selenium-webdriver
   sendgrid-actionmailer (~> 3.2)
   simple_form (~> 5.1)

app/assets/stylesheets/mailgun_mails.css

@@ -9,6 +9,15 @@
   font-size: 14px;
 }
 
+/* Add CSS variable for repetitive colors */
+
+:root {
+    --red: #D0021B;
+    --lightblue: #348eda;
+    --orange: #ff9f00;
+    --lightgreen: #68B90F;
+  }
+
 img {
   max-width: 100%;
 }
@@ -136,15 +145,15 @@ p li, ul li, ol li {
     LINKS & BUTTONS
 ------------------------------------- */
 a {
-  color: #348eda;
+  color: var(--lightblue);
   text-decoration: underline;
 }
 
 .btn-primary {
   text-decoration: none;
   color: #FFF;
-  background-color: #348eda;
-  border: solid #348eda;
+  background-color: var(--lightblue);
+  border: solid var(--lightblue);
   border-width: 10px 20px;
   line-height: 2em;
   /* 2em * 14px = 28px, use px to get airier line-height also in Thunderbird, and Yahoo!, Outlook.com, AOL webmail clients */
@@ -160,9 +169,9 @@ a {
 .btn-warning {
     text-decoration: none;
     color: #FFF;
-    background-color: #ff9f00;
-    border: solid #ff9f00;
-    border-color: #ff9f00;
+    background-color: var(--orange);
+    border: solid var(--orange);
+    border-color: var(--orange);
     border-width: 10px 20px;
     line-height: 2em;
     /* 2em * 14px = 28px, use px to get airier line-height also in Thunderbird, and Yahoo!, Outlook.com, AOL webmail clients */
@@ -178,9 +187,9 @@ a {
 .btn-success {
     text-decoration: none;
     color: #FFF;
-    background-color: #68B90F;
-    border: solid #68B90F;
-    border-color: #68B90F;
+    background-color: var(--lightgreen);
+    border: solid var(--lightgreen);
+    border-color: var(--lightgreen);
     border-width: 10px 20px;
     line-height: 2em;
     /* 2em * 14px = 28px, use px to get airier line-height also in Thunderbird, and Yahoo!, Outlook.com, AOL webmail clients */
@@ -196,9 +205,9 @@ a {
 .btn-danger {
     text-decoration: none;
     color: #FFF;
-    background-color: #D0021B;
-    border: solid #D0021B;
-    border-color: #D0021B;
+    background-color: var(--red);
+    border: solid var(--red);
+    border-color: var(--red);
     border-width: 10px 20px;
     line-height: 2em;
     /* 2em * 14px = 28px, use px to get airier line-height also in Thunderbird, and Yahoo!, Outlook.com, AOL webmail clients */
@@ -257,13 +266,13 @@ a {
   font-size: 16px;
 }
 .alert.alert-warning {
-  background-color: #FF9F00;
+  background-color: var(--orange);
 }
 .alert.alert-bad {
-  background-color: #D0021B;
+  background-color: var(--red);
 }
 .alert.alert-good {
-  background-color: #68B90F;
+  background-color: var(--lightgreen);
 }
 
 /* -------------------------------------

app/controllers/learning_materials_controller.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class LearningMaterialsController < ApplicationController
+  skip_before_action :authenticate_user!, only: %i[index]
+
+  def index
+    @learning_materials = LearningMaterial.includes(:thumbnail_blob).all
+    @learning_materials_with_thumbnails = @learning_materials.select do |learning_material|
+      learning_material.thumbnail.attached?
+    end
+    @random_learning_materials = @learning_materials_with_thumbnails.sample(2)
+    @learning_materials_with_or_without_thumbnails = @learning_materials - @random_learning_materials
+  end
+end

app/helpers/learning_materials_helper.rb

@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+module LearningMaterialsHelper
+end

app/models/learning_material.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class LearningMaterial < ApplicationRecord
+  # Associations
+  belongs_to :user
+  has_one_attached :thumbnail
+
+  # Enum
+  enum tag: { beginners: 0, intermediates: 1, experts: 2 }
+
+  # Validations
+  validates :tag, :learning_material_title, :learning_material_description, :learning_material_link, presence: true
+  validates :learning_material_link,
+            format: { with: URI::DEFAULT_PARSER.make_regexp(%w[http https]), message: :invalid_url }
+end

app/models/user.rb

@@ -10,6 +10,7 @@ class User < ApplicationRecord
   # Associations
   has_many :users_chapters, dependent: :nullify
   has_many :chapters, through: :users_chapters
+  has_many :learning_materials, dependent: :nullify
 
   # Callbacks
   before_create :set_defaults # Set model defaults before create

app/views/layouts/_footer.html.erb

@@ -21,7 +21,7 @@
 
             <li><%= link_to 'Chapters', chapters_path %></li>
 
-            <li><%= link_to 'Learning materials', landing_learn_path %></li>
+            <li><%= link_to 'Learning materials', learning_materials_path %></li>
 
             <% if FeatureFlag.find_by(name: 'projects').try(:enabled) %>
               <li><%= link_to 'Projects', '#' %></li>

app/views/layouts/application.html.erb

@@ -44,7 +44,7 @@
                 <li><a href="#">Projects</a></li>
               <% end %>
 
-              <li><%= link_to 'Learning Materials', landing_learn_path %></li>
+              <li><%= link_to 'Learning Materials', learning_materials_path %></li>
 
               <% if user_signed_in? %>
                 <li><%= button_to "Sign out", destroy_user_session_path, method: :delete %></li>
@@ -85,7 +85,7 @@
               </a>
             <% end %>
 
-            <%= link_to 'Learning Materials', landing_learn_path,
+            <%= link_to 'Learning Materials', learning_materials_path,
                         class: 'text-sm font-small text-gray-500 hover:text-red-600' %>
           </nav>
           <% if user_signed_in? %>