Ruby on Rails: form_for works, but remote_form_for doesn't

<% remote_form_for(@media, :url => url_for(:controller => :attachments,
                :action => :add_from_disk, :object_id => @object),
                :html => { :multipart => true, :id => 'new_media', :onsubmit=>'unsaved_changes = false' } ) do |f| %>

but if I change the remote_form_for to form_for, I don't get this error:

ActiveRecord::RecordInvalid (Validation failed: Document file name must be set.):

Why would it work开发者_如何学JAVA with form_for, but not the AJAX version?

You can't upload a file using AJAX.... You'll need to implement a flash uploader to send files in the background. It's not pretty, but Uploadify is pretty cool

Recommend keeping file uploading as regular form for.

Or you can use the jQuery form plugin, which works great. In this case you'd do a normal form_for, and inside of your javascript file (once you've included jquery and the jQForm lib in your html) you'd do something like this:

$(function() { 
  $("#myFormDomID").ajaxForm({ iFrame : true }); 

});