arailsdemo 5

Scaffolding 生成　Snippet

> rails g scaffold snippet caption:string content:text language:string section_id:integer

给 Snippet 的 Language 添加‘默认值’

db/migrate/2010…_create_snippets.rb　　　　

      t.string :language, default: 'ruby'
  def change
    create_table :snippets do |t|
      t.string :caption
      t.text :content
      t.string :language, default: 'ruby'
      t.integer :section_id

      t.timestamps
    end
  end
end

给 Snippet model 添加点东西

app/models/snippet.rb

class Snippet < ActiveRecord::Base
  belongs_to :section

  validates :caption, :presence => true
  validates :content, :presence => true

  def post_sequence
    section.post.sequence if section.post
  end
end

同上，更改 Section Model

app/models/section.rb

class Section < ActiveRecord::Base
  ...
  has_one :snippet, :dependent => :destroy
  accepts_nested_attributes_for :snippet, :reject_if => lambda{ |a| a[:content].blank? && a[:caption].blank? }
  ...
end

再同上，更改 Post Form

app/views/posts/_form.html.haml

            = snippet_f.input :language, :as => :select, :collection => coderay_languages

= simple_form_for(@post) do |f|
  = render 'shared/error_messages', :target => @post

  .inputs
    ...
    = f.simple_fields_for :sections do |section_f|
      .section
        ...

        = section_f.simple_fields_for :snippet do |snippet_f|
          .snippet
            %h3 Snippet
            = snippet_f.input :caption, :required => false
            = snippet_f.input :content, :input_html => {:rows =>5}, :required => false
            = snippet_f.input :language, :as => :select, :collection => coderay_languages
        %hr

添加代码高亮 Coderay

# Gemfile
gem 'coderay'
_________________

# Terminal
> bundle install

为 Coderay 书写　辅助方法

app/helpers/application_helper.rb

      CodeRay.scan(text, lang).div(
  def coderay(text, lang)
      CodeRay.scan(text, lang).div(
          :css => :class,
          :tab_width => 2)
  end

  def coderay_languages
    Hash[*CODERAY_LANGUAGES.map {|l| [l.humanize, l] }.flatten]
  end
end

一些常量(Constants)

config/initializers/constants.rb

CODERAY_LANGUAGES =  ["css", "html", "java_script", "json",
                      "ruby", "sql", "xhtml", "yaml"]

改进我们的 Post controller (重构并加入新东西)

app/models/post.rb and app/controllers/posts_controller.rb

# post.rb

class Post < ActiveRecord::Base
  ...  
  def build_section_and_snippet
    sections.build if sections.empty?
    sections.each{ |section| section.build_snippet if section.snippet.nil?}
  end
end
________________________________

# posts_controller.rb

class PostsController < ApplicationController
  ...
  def new
    @post = Post.new(:sequence => Post.count + 1)  

    @post.build_section_and_snippet
  end

  def edit
    @post = Post.find(params[:id])
    @post.build_section_and_snippet
  end
end

稍微调整 Post model

app/models/post.rb

class Post < ActiveRecord::Base
  ...
  accepts_nested_attributes_for :sections,
    :reject_if => proc { |attr| attr['heading'].blank? && attr['body'].blank? }