ruby-on-rails - rails 3 : How to create a new nested resource?

Question

Getting Started Rails Guide有点掩盖了这部分，因为它没有实现评论 Controller 的"new"操作。在我的应用程序中，我有一个包含许多章节的书籍模型:

class Book < ActiveRecord::Base
  has_many :chapters
end

class Chapter < ActiveRecord::Base
  belongs_to :book
end

在我的路线文件中:

resources :books do
  resources :chapters
end

现在我想实现章节 Controller 的"new"操作:

class ChaptersController < ApplicationController
  respond_to :html, :xml, :json

  # /books/1/chapters/new
  def new
    @chapter = # this is where I'm stuck
    respond_with(@chapter)
  end

执行此操作的正确方法是什么？另外， View 脚本(表单)应该是什么样子？

Answer 1

首先，你必须在章节 Controller 中找到相应的书来为他构建一个章节。您可以像这样执行操作:

class ChaptersController < ApplicationController
  respond_to :html, :xml, :json

  # /books/1/chapters/new
  def new
    @book = Book.find(params[:book_id])
    @chapter = @book.chapters.build
    respond_with(@chapter)
  end

  def create
    @book = Book.find(params[:book_id])
    @chapter = @book.chapters.build(params[:chapter])
    if @chapter.save
    ...
    end
  end
end

在您的表单中，new.html.erb

form_for(@chapter, :url=>book_chapters_path(@book)) do
   .....rest is the same...

或者你可以尝试简写

form_for([@book,@chapter]) do
    ...same...