Rails 3: How to create a new nested resource?

Question

The Getting Started Rails Guide kind of glosses over this part since it doesn't implement the "new" action of the Comments controller. In my application, I have a book model that has many chapters:

class Book < ActiveRecord::Base   has_many :chapters end  class Chapter < ActiveRecord::Base   belongs_to :book end 

In my routes file:

resources :books do   resources :chapters end 

Now I want to implement the "new" action of the Chapters controller:

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 

What is the right way to do this? Also, What should the view script (form) look like?

Answer 1

First you have to find the respective book in your chapters controller to build a chapter for him. You can do your actions like this:

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 

In your form, new.html.erb

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

or you can try a shorthand

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