MultipartFormFor

Create multipart Ajax forms. There is a security restriction with javascript to prevent access to the filesystem. To get around the AJAX/file upload problem we make use of the iframe remoting pattern. It's based on the following blog post: http://khamsouk.souvanlasy.com/2007/5/1/ajax-file-uploads-in-rails-using-attachment_fu-and-responds_to_parent

Example

In your View:

<div id="product_<%= @product.id %>" >
  <% multipart_remote_form_for(@product) do |f| %>
    <%= f.error_messages %>
    <%= f.file_field :image, :onchange => 'this.form.submit()' %>
  <% end %>
</div>

which results in:

<form enctype="multipart/form-data" class="edit_post" action="/posts/#{post.id}" method="post"
              id="edit_post_#{post.id}" target="upload_frame_for_#{post.id}">
  <div style="margin:0;padding:0"><input name="_method" type="hidden" value="put" /></div>
  <input id="product_image" name="product[image]" onchange="this.form.submit()" size="30" type="file" />    
</form>
<iframe id="upload_frame_for_#{post.id}"
    name="upload_frame_for_#{post.id}"
    style="width:1px;height:1px;border:1px"
    src="about:blank"></iframe>

And in your Controller:

def update
  @product = Product.find(params[:id])
  if @product.update_attributes(params[:product])
    responds_to_parent do
      render(:update) do |page|
        page.replace_html("product_#{@product.id}",
          {:partial => 'form', :locals => { :product => @product }})
      end
    end
  end
end

Install

It requires the responds_to_parent plugin

script/plugin install git://github.com/markcatley/responds_to_parent.git

script/plugin install git://github.com/p8/multipart_form_for.git

Copyright (c) 2009 Petrik de Heus, released under the MIT license