attachment_fu file upload optional in 'new' view?

In my 'new' view for an Item object, the user can upload a picture of
the item. How can I make the upload optional (while creating the new
item)? I'm using REST and this is a portion of what my controller
looks like to make it Mandatory to upload an image:

respond_to do |format|
      if and

Now if I remove the no image will be created (even if it
is valid).

Okay I figured it out. I assigned the @photo to @item: = @photo

respond_to do |format|

Attachment_fu is a great plugin!