Ruby on rails nested form model

Question

Hi all,

I'm trying to use rails nested form_for helper, but I am getting the following error:

BlogPage(#49859550) expected, got Array(#31117360)

Here are my model objects:

class Blog < ActiveRecord::Base
  # Table Configuration
  set_table_name "blog"

 # Model Configuration
 belongs_to :item
 has_many :blog_pages
 accepts_nested_attributes_for :blog_pages, :allow_destroy => true
end

class BlogPage < ActiveRecord::Base
  # Table Configuration
  set_table_name "blog_page"

  # Model Configuration
  belongs_to :blog
end

Here is the form I generated (left out unnecessary HTML):

<% form_for :blog, :url => { :action => :create } do |blog_form| %>  
    <%= blog_form.text_field :title, :style => "width: 400px" %>  
    <% blog_form.fields_for :blog_pages do |page_fields| %>
        <% @blog.blog_pages.each do |page| %>  
            <%= page_fields.text_area :content, :style => "width: 100%",
                :cols => "10", :rows => "20" %>
        <% end %>
    <% end %>
<% end %>

Here are the parameters that are sent to the controller:

{"commit"=>"Save", "blog"=>{"blog_pages"=>{"content"=>"This is the new blog entries contents."}, "title"=>"This is a new blog entry.", "complete"=>"1"}, "authenticity_token"=>"T1Pr1g9e2AjEMyjtMjLi/ocrDLXzlw6meWoLW5LvFzc="}

Here is the BlogsController with the create action that gets executed:

class BlogsController < ApplicationController
  def new
    @blog = Blog.new # This is the line where the error gets thrown.  
    # Set up a page for the new blog so the view is displayed properly.
    @blog.blog_pages[0] = BlogPage.new
    @blog.blog_pages[0].page_number = 1
    respond_to do |format|
      format.html # Goes to the new.html.erb view.
      format.xml { render :xml => @blog }
      format.js { render :layout => false}
    end
  end

  def create
    @blog = Blog.new(params[:blog])

    respond_to do |format|
      if @blog.save
        render :action => :show
      else
        flash[:notice] = "Error occurred while saving the blog entry."
        render :action => :new
      end
    end
  end
end

If anyone can help me with this I would greatly appreciate it. I'm still pretty new to ruby and the rails framework and couldn't solve the problem on my own by googling.

Thanks.

Answer 1

Have you seen this?

http://media.pragprog.com/titles/fr_arr/multiple_models_one_form.pdf

Answer 2

Change your form to this:

<% form_for :blog, :url => { :action => :create } do |blog_form| %>  
    <%= blog_form.text_field :title, :style => "width: 400px" %>  
    <% blog_form.fields_for :blog_pages do |page_fields| %>
            <%= page_fields.text_area :content, :style => "width: 100%",
                :cols => "10", :rows => "20" %>
    <% end %>
<% end %>

If you use fields_for it iterates over blog_pages automaticaly. However I'm not sure if this caused errors.