asset partial

<div class="asset">
  <% if asset.new_record? %>
    <% fields_for "page[new_asset_attributes][]", asset do |asset_form| -%> 
      <p>
        <%= asset_form.file_field :file %> 
        <%= link_to_function "remove", "$(this).up('.asset').remove()" %> 
      </p>
    <% end -%>
  <% else %>
      <p>
        <% fields_for "page[existing_asset_attributes][]", asset do |asset_form| -%>
          <%= asset_form.hidden_field(:file) %>
        <% end %>
        <%= image_tag asset.file.url(:small) %> 
        <%= link_to_function "remove", "$(this).up('.asset').remove()" %> 
      </p>
  <% end %>
</div>

error on update after removing an attachment

wrong number of arguments (1 for 0)

app/models/page.rb:21:in `delete'
app/models/page.rb:21:in `existing_asset_attributes='
app/models/page.rb:16:in `each'
app/models/page.rb:16:in `existing_asset_attributes='
app/controllers/pages_controller.rb:76:in `update'
app/controllers/pages_controller.rb:75:in `update'

{"commit"=>"Update",
 "_method"=>"put",
 "authenticity_token"=>"5d3b9b14bc062c461bdc64eca48e10c8c17c9d48",
 "id"=>"11",
 "page"=>{"permalink"=>"agaaaaain",
 "name"=>"foo",
 "existing_asset_attributes"=>{"33"=>{"file"=>"/files/33/original/100_0450.JPG?1228809588"},
 "32"=>{"file"=>"/files/32/original/100_0160.JPG?1228809584"}},
 "content"=>"foo"}}

existing attributes writer method

  def existing_asset_attributes=(asset_attributes) 
    assets.reject(&:new_record?).each do |asset| 
      attributes = asset_attributes[asset.id.to_s] 
      if attributes 
        asset.attributes = attributes 
      else 
        asset.delete(asset) 
      end 
    end 
  end