Inline file upload error: undefined method `size='

Hello,

I followed the tutorial at:
http://khamsouk.souvanlasy.com/2007/5/1/ajax-file-uploads-in-rails-using-attachment_fu-and-responds_to_parent

However, in my controller I am getting the error:

NoMethodError (undefined method `size=’ for #SwfImage:0x5705b48)

Other references to this error indicate that the render method is
trying to render a string (which does have a size method) but it’s
attempting to render the SwfImage object instead. So how would I get
around this? Any help would be appreciated.

VIEW CODE

<% form_for(:swf_image, :url => formatted_swf_images_path(:format =>
‘js’), :html => { :multipart => true, :target => ‘upload_frame’ }) do |
f| %>

Filename
<%= f.file_field :uploaded_data %>

<%= f.submit "Create" %>

<% end %>

CONTROLLER CODE

def create
@swf_image = SwfImage.new(params[:swf_image])

respond_to do |format|
  if @swf_image.save
    flash[:notice] = 'Image was successfully saved.'
    format.html { redirect_to(@swf_image) }
    format.js do
      responds_to_parent do
        render :update do |page|
          page.insert_html :bottom, "swf_images", :partial =>

‘swf_images/image’, :object => @swf_image
page.visual_effect :highlight, “image_#{@swf_image.id}”
end
end
end
else
format.html { render :action => “new” }
format.js do
responds_to_parent do
render :update do |page|
# do nothing
end
end
end
end
end
end