Rails6.0 | 動画学習サイトを作成| 27 | Markdown関数 - 学生向けプログラミング入門

[26]プロジェクトビュー　<<　[ホームに戻る]　>> [28]動画（Wistia）

Markdown関数を利用できるように実装していきます。

Markdown関数の詳しい使用方法は下記のページを参照して下さい。
guides.github.com

記述追加　GemFile(89行目)

gem 'redcarpet', '~> 3.5'
gem 'coderay', '~> 1.1', '>= 1.1.3'

GemFile

source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }

ruby '2.6.3'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 6.0.3', '>= 6.0.3.1'
# Use postgresql as the database for Active Record
gem 'pg', '>= 0.18', '< 2.0'
# Use Puma as the app server
gem 'puma', '~> 4.1'
# Use SCSS for stylesheets
gem 'sass-rails', '>= 6'
# Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker
gem 'webpacker', '~> 4.0'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.7'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use Active Model has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use Active Storage variant
# gem 'image_processing', '~> 1.2'

# Reduces boot times through caching; required in config/boot.rb
gem 'bootsnap', '>= 1.4.2', require: false

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
end

group :development do
  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
  gem 'web-console', '>= 3.3.0'
  gem 'listen', '~> 3.2'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
  gem 'spring-watcher-listen', '~> 2.0.0'
end

group :test do
  # Adds support for Capybara system testing and selenium driver
  gem 'capybara', '>= 2.15'
  gem 'selenium-webdriver'
  # Easy installation and use of web drivers to run system tests with browsers
  gem 'webdrivers'
end

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

# Bulma
gem 'bulma-rails', '~> 0.7.4'
gem 'bulma-extensions-rails', '~> 1.0.30'

#デバイス
gem 'devise'

# 日本語化
gem 'rails-i18n'

# google認証
gem 'omniauth'
gem 'omniauth-google-oauth2'

# アマゾンS3
gem "aws-sdk"

#管理ダッシュボード
gem 'trestle', '=0.8.12'
gem 'trestle-auth', '=0.2.5'

# trestle検索
gem 'trestle-search', '~> 0.3.0'

# trestle画像アップロードと表示
gem 'trestle-active_storage', '~> 2.2', '>= 2.2.1'
gem "mini_magick"
gem 'image_processing', '~> 1.2'

# trestleリッチテキスト
gem 'trestle-tinymce', '~> 0.1.3'

# Markdown関数
gem 'redcarpet', '~> 3.5'
gem 'coderay', '~> 1.1', '>= 1.1.3'

コマンド
bundle

「app\helpers\application_helper.rb」ファイルの記述を以下のように編集します。

記述追加　app\helpers\application_helper.rb(21行目)

    class CodeRayify < Redcarpet::Render::HTML
        def block_code(code, language)
            CodeRay.scan(code, language).div(:line_numbers => :table)
        end
    end
    
    def markdown(text)
        coderayified = CodeRayify.new(:filter_html => true, :hard_wrap => true)
        options = {
            :fenced_code_blocks => true,
            :no_intra_emphasis => true,
            :autolink => true,
            :strikethrough => true,
            :lax_html_blocks => true,
            :superscript => true
        }
        markdown_to_html = Redcarpet::Markdown.new(coderayified, options)
        markdown_to_html.render(text).html_safe
    end

app\helpers\application_helper.rb

module ApplicationHelper

    def avatar_url(user)
        if user.avatar.attached?
            url_for(user.avatar)
        elsif user.image?
            user.image
        else
            ActionController::Base.helpers.asset_path('icon_default_avatar.jpg')
        end
    end

    def project_cover(project)
        if project.images.attached?
            url_for(project.images[0])
        else
            ActionController::Base.helpers.asset_path('icon_default_image.jpg')
        end
    end           

    class CodeRayify < Redcarpet::Render::HTML
        def block_code(code, language)
            CodeRay.scan(code, language).div(:line_numbers => :table)
        end
    end
    
    def markdown(text)
        coderayified = CodeRayify.new(:filter_html => true, :hard_wrap => true)
        options = {
            :fenced_code_blocks => true,
            :no_intra_emphasis => true,
            :autolink => true,
            :strikethrough => true,
            :lax_html_blocks => true,
            :superscript => true
        }
        markdown_to_html = Redcarpet::Markdown.new(coderayified, options)
        markdown_to_html.render(text).html_safe
    end

end

「app\views\task\show.html.erb」ファイルを編集します。

記述編集　app\views\task\show.html.erb

  <section class="section">
    <div class="container">
        <div class="col m8">
            <div class="card z-depth-2">
                <%= @task.video %>
                <div class="row">
                </div>
                <div class="card-action grey-text text-darken-4">
                    <div class="container">
                        <div class="notification">
                            <%= @task.title %>
                        </div>
                    </div>
                    
                    <div class="box">
                        <span class="tag is-white is-large"> <%= @task.description %></span>
                    </div>
                    <% if !@task.note.blank? %>
                        <div class="box">
                            <%= markdown(@task.note) %>
                        </div>   
                    <% end %>                 
                </div>
            </div>
        </div>
        <!-- タスク Section -->
        <div class="box">
            <article class="media">
                <div class="media-content">
                    <div class="content">
                        <div class="collection">
                            <% @tasks.each do |task| %>
                                <% if task.header %>
                                    <br/>
                                    <div class="collection-item active">
                                        <span class="tag is-link is-large"> <%= task.title %></span>
                                        <span class="tag is-white is-large"> <%= task.description %></span>
                                    </div>
                                    <br/>
                                <% else %>
                                    <div class="collection-item active">
                                        &nbsp;&nbsp;&nbsp;&nbsp;<span class="tag is-light is-medium" style="margin: 3px;">
                                            <%= link_to [task.project, task], class: "collection-item" do %>
                                                <%= task.title %>
                                            <% end %>                                                                
                                            </span>
                                        
                                    </div>                            
                                <% end %>
                            <% end %>
                        </div>
                    </div>
                </div>
            </article>
        </div>
 
    </div>
  </section>

以下のようなMarkdown記法が利用できます。
タスクテーブルの「note」フィールドに記述を入力して下さい。

ルビーのコードを書く場合
<br>

```ruby
  def index
  	@projects = Project.all
  end

  def show
  	@project = Project.find(params[:id])
  	@tasks = @project.tasks
  end
```

<br>
Javascriptを書く場合
<br>

```javascript
function fancyAlert(arg) {
  if(arg) {
    $.facebox({div:'#foo'})
  }
}
```

ブラウザ確認
http://localhost:3000/project/1/task/3

まだビデオ表示を実装していませんが、タスクの詳細が見れるようになりました。