Nested model/form doesn't create an entry

Question

While delving into ruby's nested models I encountered an issue.

Consider the following scenario,

I have the following models:

Author
Book

With the following specifications:

Author:

class Author < ActiveRecord::Base
  attr_accessible :name
  has_many :books, dependent: :destroy

  accepts_nested_attributes_for :books #I read this is necessary here: http://stackoverflow.com/questions/12300619/models-and-nested-forms

  # and some validations...
end

Book:

class Book < ActiveRecord::Base
  attr_accessible :author_id, :name, :year
  belongs_to :author

  #and some more validations...
end

I would like to add a book to an author. Here is my authors_controller:

def new_book
  @author = Author.find(params[:id])
end

def create_book
  @author = Author.find(params[:id])
  if @author.books.create(params[:book]).save
    redirect_to action: :show
  else
    render :new_book
  end
end

And this is the form with which I try doing it:

<h1>Add new book to <%= @author.name %>'s collection</h1>
<%= form_for @author, html: { class: "well" } do |f| %>
    <%= fields_for :books do |b| %>
        <%= b.label :name %>
        <%= b.text_field :name %>
        <br/>
        <%= b.label :year %>
        <%= b.number_field :year %>
    <% end %>
    <br/>
    <%= f.submit "Submit", class: "btn btn-primary" %>
    <%= f.button "Reset", type: :reset, class: "btn btn-danger" %>
<% end %>

Problem: When I type in the data and click "submit" it even redirects me to the correct author, but it doesn't save a new record for that author. After a lot of research I can't seem to find what I am doing wrong here.

Firoz Ansari · Accepted Answer · 2012-10-18 20:53:11Z

1

Change authors_controller to:

def new_book
  @author = Author.find(params[:id])
  @book = Book.new
end

Your form to:

<h1>Add new book to <%= @author.name %>'s collection</h1>
<%= form_for ([@author, @book]), html: { class: "well" } do |f| %>

And, routes.rb

resources :authors do
  resources :books
end

edited Oct 18, 2012 at 20:53

answered Oct 18, 2012 at 20:43

Firoz Ansari

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2 Comments

Dennis Hackethal Over a year ago

Apparently that changed my routing mechanism... It now gives me undefined method `author_books_path' and refers to the second line of the form...

Firoz Ansari Over a year ago

Please refer blog.dominicsayers.com/2011/08/24/… which has child form implementation from scratch.

Syed Aslam · Accepted Answer · 2012-10-18 20:54:33Z

1

You're missing a couple of things.

Controller:

...
def new_book
  @author = Author.find(params[:id])
  @author.books.build
end
...

View, it is f.fields_for and not just fields_for:

<%= f.fields_for :books do |b| %>
  <%= b.label :name %>
  <%= b.text_field :name %>
  <br/>
  <%= b.label :year %>
  <%= b.number_field :year %>
<% end %>

answered Oct 18, 2012 at 20:54

Syed Aslam

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1 Comment

Dennis Hackethal Over a year ago

That looks better already, but now it is asking me for a create method in the books controller - any idea why?

ichigolas · Accepted Answer · 2012-10-18 21:35:26Z

1

You also need to add :nested_attributes_for_books on your Author model accessible methods. The create method on you Author controller doesn't need any code additions to get going.

Note: You set the Books controller to render 'books#show' on success. If the app is redirecting you to the author that means the Author controller is handling the creation of the book, unless you set it to redirect to author and not the book.

answered Oct 18, 2012 at 21:35

ichigolas

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