Multiple File Upload In Rails

_form.html.erb

<% form_for(@album, :html => { :multipart => true }) do |f| %>
  
  <p>
    <%= f.label :name %>
    <%= f.text_field :name %>
  </p>
  
  <h2>Photo(s)</h2>
    <div id="photos">
      <% if @album.new_record? %>
         <%= render :partial => 'photo', :locals => { :form => f, :photo => @album.photos.build } %>
      <% else %>
        <% @album.photos.each do |photo| %>
          <%= image_tag photo.upload.url(:small) %>
        <% end %>
      <% end %>
  </div>
  <%= add_object_link("New Photo", f, @album.photos.build, "photo", "#photos") %>
  
  <p><%= f.submit %></p>
<% end %>

_photo.html.erb

<div class="photo">
  <%= form.fields_for :photos, photo, :child_index => (photo.new_record? ? "index_to_replace_with_js" : nil) do |photo_form| %>
    <p>
      <%= photo_form.label :title %>
      <%= photo_form.text_field :title %>
      <%= photo_form.file_field :upload %>
      <%= link_to_function "delete", "remove_field($(this), ('.photo'))" %>
    </p>
  <% end %>
</div>

album.rb

class Album < ActiveRecord::Base
  has_many :photos, :dependent => :destroy
  accepts_nested_attributes_for :photos, :allow_destroy => true
end

albums_helper.rb

module AlbumsHelper
  def add_object_link(name, form, object, partial, where)
      html = render(:partial => partial, :locals => { :form => form}, :object => object)
      link_to_function name, %{
        var new_object_id = new Date().getTime() ;
        var html = jQuery(#{js html}.replace(/index_to_replace_with_js/g, new_object_id)).hide();
        html.appendTo(jQuery("#{where}")).slideDown('slow');
      }
    end

    def js(data)
      if data.respond_to? :to_json
        data.to_json
      else
        data.inspect.to_json
      end
    end
end

application.html.erb

<%= javascript_include_tag :defaults, 'jquery-1.3.2.min' %>
<script>
   jQuery.noConflict();
</script>

application.js

function remove_field(element, item) {
  element.up(item).remove();
}

index.html.erb

<h1>Listing albums</h1>

<table>
  <tr>
    <th>Name</th>
    <th>Photo Title</th>
    <th>Photos</th>
  </tr>

<% @albums.each do |album| %>
  <tr>
    <td><%=h album.name %></td>
  <% album.photos.each do |photo| %>
    <td><%=h photo.title %></td>
    <td><%= image_tag photo.upload.url(:thumb) %></td>
  <% end %>
    <td><%= link_to 'Show', album %></td>
    <td><%= link_to 'Edit', edit_album_path(album) %></td>
    <td><%= link_to 'Destroy', album, :confirm => 'Are you sure?', :method => :delete %></td>
  </tr>
<% end %>
</table>

<br />

<%= link_to 'New album', new_album_path %>

photo.rb

class Photo < ActiveRecord::Base

  belongs_to :album
  has_attached_file :upload,
                    :url => "/images/:id/:style/:basename.:extension",
                    :path => ":rails_root/public/images/:id/:style/:basename.:extension",
                    :styles => {
                      :thumb => "75x75>",
                      :small => "200x200>"
                    }
  #add in any validations you may want
end

routes.rb

resources :albums do
  resources :photos
end

show.html.erb

<p>
  <b>Name:</b>
  <%=h @album.name %><br />
  
  <% @album.photos.each do |photo| %>
    <h3><%=h photo.title %></h3>
    <%= image_tag photo.upload.url(:small) %>
  <% end %>
</p>


<%= link_to 'Edit', edit_album_path(@album) %> |
<%= link_to 'Back', albums_path %>

http://railsforum.com/viewtopic.php?id=35044