rails 2.3 nested forms with has_many through checkboxes

rubyonrails-talk
1

I was wondering if anyone knew of a way to combine the new nested forms in rails 2.3 with a has_many through relationship via checkboxes. Basically I have a page model, a page_category model and a category_items join table. Pages have many page categories through category items. The category_items table is polymorphic so i can use it for other models who need categories (maybe this is overcomplicating everything though?).

In a page's edit form I want to be able to dynamically add new category fields and then associate the new ones I create and the other already created page categories to the current page via checkboxes. Hopefully this makes sense and can actually be done, I'd rather not have to go to another controller/form just to create and edit page categories.

class Page < ActiveRecord::Base         has_many :category_items, :as => :item, :dependent => :destroy   has_many :page_categories, :through => :category_items, :source => :category, :source_type => "PageCategory", :uniq => true   accepts_nested_attributes_for :page_categories, :allow_destroy => true, :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } } end

class PageCategory < ActiveRecord::Base   has_many :pages, :through => :category_items, :source => :item, :source_type => 'Page', :uniq => true end

class CategoryItem < ActiveRecord::Base   belongs_to :category, :polymorphic => true   belongs_to :item, :polymorphic => true end

Page Category partial for my page form (hooks into a jquery script to dynamically add/remove page category form fields)...

<a href="#" id="page_categories" class="header">Categories<%= hidden_field_tag "page[page_category_ids]", "" %></a> <ul class="submenu">   <%- for category in PageCategory.all -%>   <li>     <%= check_box_tag "page[page_category_ids]", category.id, @page.page_categories.include?(category), :class => "checkbox" %>&nbsp;<% f.fields_for category do |category_form| %><%= category_form.text_field :title, :style => "width: 200px;", :class => "textfield small formElement" %><% end %>   </li>   <%- end -%> </ul>

Right now, if I try and create or update a page I get the following error...

ActiveRecord::UnknownAttributeError in Admin/pagesController#update

unknown attribute: page_category RAILS_ROOT: /Users/rajo/Sites/boilerplate

Application Trace | Framework Trace | Full Trace /Users/rajo/Sites/boilerplate/vendor/rails/activerecord/lib/ active_record/base.rb:2745:in `attributes=' /Users/rajo/Sites/boilerplate/vendor/rails/activerecord/lib/ active_record/base.rb:2741:in `each' /Users/rajo/Sites/boilerplate/vendor/rails/activerecord/lib/ active_record/base.rb:2741:in `attributes=' /Users/rajo/Sites/boilerplate/vendor/rails/activerecord/lib/ active_record/base.rb:2627:in `update_attributes' /Users/rajo/Sites/boilerplate/app/controllers/admin/ pages_controller.rb:107:in `update' /Users/rajo/Sites/boilerplate/app/controllers/admin/ pages_controller.rb:106:in `update' Request

Parameters:

{"commit"=>"Save", "_method"=>"put", "authenticity_token"=>"DvvJPsU9c942x1Ak5wOIm8V4wYv8AClftKJ7ohGqOo0=", "id"=>"about", "page"=>{"name"=>"About", "title"=>"About Us", "body"=>"<p>About this site.</p>", "published"=>"1", "page_category"=>{"title"=>"Default Two"}, "page_category_ids"=>["", "1", "2"], "home"=>"0"}} Show session dump

Response

Headers:

{"Content-Type"=>"", "Cache-Control"=>"no-cache"}

Thanks for any help in advance.