arailsdemo 3

Scaffolding 生成　section

> rails g scaffold section heading:string body:text position:integer post_id:integer

> rake db:migrate

　给　section model 添点料

app/models/section.rb

class Section < ActiveRecord::Base
  default_scope order("position ASC")
  belongs_to :post

  validates :heading, :presence => true
  validates :body, :presence => true
  validates :position, :presence => true,
                       :numericality => { :greater_than => 0}
end

给　post model 添点料

app/models/post.rb

class Post < ActiveRecord::Base
...
  has_many :sections, :dependent => :destroy
  accepts_nested_attributes_for :sections, :reject_if => :all_blank
...
end

accepts_nested_attributes_for 可以参考 Railscasts #196

将 post 表单改为 嵌套(Nested)　表单

app/views/posts/_form.html.haml

= simple_form_for @post do |f|
...
  = f.simple_fields_for :sections do |section_f|
    .section
      %h2 Section
      = section_f.input :heading
      = section_f.input :body, :input_html => {:rows =>5}
      = section_f.input :position

  = f.button :submit

修改 Posts Controller 的 new 方法

app/controllers/post_controller.rb

def new
  @post = Post.new(:sequence => Post.count + 1)  
  @post.sections.build
end

更改 Post 的 Show 页面

app/views/posts/show.html.haml

%h1= "\##{@post.sequence} #{@post.title}"
%p= sanitize @post.description

- for section in @post.sections
  .section
    %h2= section.heading
    .body= sanitize section.body
    %hr