<%= form_for(@product) do |f| %>

<%= f.label :name %> <%= f.text_field :name %>

<%= f.label :category_ids %> <%= f.token_field :category_ids, :token_url => token_categories_path, :append_to_id => :id %>

<%= f.submit %> <% end %> <%= link_to "Listing", products_path %>