How to display photos on edit and file_field on new

My form partial is being used to create new, and also for editing.

<% form_for @deal, :html => { :multipart => true } do |f| %>   <%= f.error_messages %>

  <p>     <%= f.label :city_id %>     <%= f.collection_select :city_id, City.find(:all), :id, :name, { :prompt => 'Select a city' }, {:class => 'foobar'} %>   </p>   <p>     <%= f.label :title %><br />     <%= f.text_field :title %>   </p>   <p>     <%= f.label :description %><br />     <%= f.text_area :description %>   </p>   <p>     <%= f.label :price %><br />     <%= f.text_field :price %>   </p>   <p>     <%= f.label :value %><br />     <%= f.text_field :value %>   </p>   <p>     <%= f.label :discount %><br />     <%= f.text_field :discount %>   </p>   <p>     <%= f.label :savings %><br />     <%= f.text_field :savings %>   </p>   <p>     <%= f.label :goal %><br />     <%= f.text_field :goal %>   </p>   <p>     <%= f.label :countdown %><br />     <%= f.text_field :countdown %>   </p>   <p>     <%= f.label :purchased %><br />     <%= f.text_field :purchased %>   </p>

  <% f.fields_for :photos do |builder| %>     <p class="fields">       <%= builder.label :photo, "Photos" %><br />

      <% if !@deal.new_record? %>

        <%= image_tag :photo.url(:small) %>       <% else %>         <%= builder.file_field :photo %>       <% end %>

      <br />

      <!--       <%= builder.check_box :_destroy %>       <%= f.label :destroy, "Remove photo" %>       -->

      <%= builder.hidden_field :_destroy %>       <%= link_to_function "remove", "remove_fields(this)" %>     </p>   <% end %>

  <p><%= link_to_add_fields "Add photos", f, :photos %></p>

  <% f.fields_for :features do |builder| %>     <p class="fields">       <%= builder.label :description, "Features" %><br />       <%= builder.text_area :description, :rows => 3 %><br />

      <!--       <%= builder.check_box :_destroy %>       <%= f.label :destroy, "Remove description" %>       -->

      <%= builder.hidden_field :_destroy %>       <%= link_to_function "remove", "remove_fields(this)" %>     </p>   <% end %>

  <p><%= link_to_add_fields "Add feature", f, :features %></p>

  <p>     <%= f.submit 'Save' %>   </p> <% end %>

Ok i used <%= image_tag builder.object.photo.url(:small) %> instead of <%= image_tag :photo.url(:small) %> Seems to work now