Question

I’ve spent hours on this one. I’m trying to use Ryan Bate’s nested_form_for
plugin in rails 3.2 though I don’t think it’s related to my issue. I tried
taking it out and I still get the same issue.

When I hit organizations/:org_id/publications/new I see the form to add a new
publication correctly. However, when I submit (with or without correct data) it
I get an unknown attribute: publications_attributes error. I’m sure there’s
something wrong with the way I’m building the related object(s) in the create
method. Any ideas?

models/organization.rb

class Organization < ActiveRecord::Base
  attr_accessible :name,
                  :publications_attributes, # fk, nested form
  has_many :publications
  accepts_nested_attributes_for :publications,
                                :allow_destroy => true

models/publication.rb

class Publication < ActiveRecord::Base
  attr_accessible :link,
                  :organization_id
  belongs_to :organization
  validates :link,
            :presence => true,
end

controllers/publications_controller.rb

class PublicationsController < ApplicationController

  def new
    @organization = current_user.organizations.first
    @organization.publications.build
  end

  def create
    @organization = current_user.organizations.first
    @organization.publications.build(params[:organization])
    if @organization.save
      flash[:notice] = "Successfully created publications"
      redirect_to @organization
    else
      render :action => 'new'
    end
  end
end

routes.rb

resources :organizations do
  resources :publications,  :only => [:new, :create]
end

views/publications/new.html.erb

<%= nested_form_for @organization, :html => { :novalidate => 'novalidate' },
                                   :method => :post,
                                   :url => organization_publications_path, do |f| %>

  <%= render 'shared/error_messages', :object => f.object %>

  <%= f.fields_for :publications do |publication_form| %>
    <%= render :partial => 'publications/form', :locals => { :f => publication_form } %>
  <% end %>
  <%= f.link_to_add "Add", :publications %>

  <%= render :partial => 'shared/submit', :locals => { :text => 'Create', :f => f } %>
<% end %>

views/publications/_form.html.erb

<div class="field">
  <%= f.label :link %>
  <%= f.text_field :link %>
</div>
<%= f.link_to_remove "Remove" %>

The submitted hash looks like this:

Parameters: {
    "utf8"=>"✓",
    "authenticity_token"=>"rhW/m8mnulZMmW7gkLYxOT8RWYoQc8eYdp2hOXkqHPU=",
    "organization"=>{
        "publications_attributes"=>{
            "0"=>{
                    "link"=>"fdsfdsfs"
            }
        }
    },
    "commit"=>"Create",
    "organization_id"=>"53"
}

Answer 1

Ok, ignore my previous answer. This is a little different than what I have done in the past, but since the organization already exists you can just call update_attributes on that. Rails (3.2 at least) will loop through all the publication_attributes and add new ones or update existing ones. In the create method try this…

if @organization.update_attributes(params[:organization])
  flash[:notice] = "Successfully created publications"
  redirect_to @organization
else
  render :action => 'new'
end