用回形针可以访问attr_多个图片

class User < ActiveRecord::Base
  attr_accessible :name, :email
  has_many :assets, :dependent => :destroy
  accepts_nested_attributes_for :assets, :allow_destroy => true
end

class Asset < ActiveRecord::Base
  attr_accessible :user_id, :image
  belongs_to :user
  has_attached_file :image,
    :styles => {
      :thumb=> \"100x100#\",
      :small  => \"300x300>\",
      :large => \"600x600>\"
    }
end

  create_table \"assets\", :force => true do |t|
    t.integer  \"user_id\"
    t.datetime \"created_at\"
    t.datetime \"updated_at\"
    t.string   \"image_file_name\"
    t.string   \"image_content_type\"
    t.integer  \"image_file_size\"
  end

  create_table \"users\", :force => true do |t|
    t.string   \"name\"
    t.string   \"email\"
    t.datetime \"created_at\"
    t.datetime \"updated_at\"
  end

<%= form_for(@user, :html => { :multipart => true }) do |f| %>
  <% if @user.errors.any? %>
    <div id=\"error_explanation\">
      <h2><%= pluralize(@user.errors.count, \"error\") %> prohibited this user from being saved:</h2>

      <ul>
      <% @user.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class=\"field\">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>
  <div class=\"field\">
    <%= f.label :email %><br />
    <%= f.text_field :email %>
  </div>

  <div class=\"newPaperclipFiles\">
    <%= f.fields_for :assets do |asset| %>
      <% if asset.object.new_record? %>
        <%= asset.file_field :image %>
      <% end %>
    <% end %>
  </div>

  <div class=\"existingPaperclipFiles\">
    <% f.fields_for :assets do |asset| %>
      <% unless asset.object.new_record? %>
        <div class=\"thumbnail\">
          <%= link_to( image_tag(asset.object.image.url(:thumb)), asset.object.image.url(:original) ) %>
          <%= asset.check_box :_destroy %>
        </div>
      <% end %>
    <% end %>
  </div>

  <div class=\"actions\">
    <%= f.submit %>
  </div>
<% end %>