<%= f.error_messages %> 
<p> 
    <%= f.label :filename %><br /> 
  <%= f.text_field :filename %> 
</p> 
<p> 
    <%= f.label :thumbnail %><br /> 
  <%= f.text_field :thumbnail %> 
</p> 
<p> 
    <%= f.label :description %><br /> 
  <%= f.text_field :description %> 
</p> 
<p> 
    <%= f.label :categories %><br /> 
  <%= f.collection_select :category_ids, @all_categories, :id, :long_name, {}, 
      { :multiple => true } %> 
</p> 
