带有编辑表单和file_field的Carrierwave Rails（未选择文件）

Question

When my edit view loads, all my fields are populated with the record detail, but the file_field shows "No file Selected" next to the browse button. I would prefer that is show the record file name instead. Why does it not show that a file that was uploaded?

Edit View

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

   <p>
       <%= f.label :file, "File" %><br />
       <%= f.file_field :file %><br />
       <%= f.hidden_field :file_cache %><br />
       <%= f.label :name, "name" %><br />
       <%= f.text_field :name %><br />
       <%= f.label :memo, "memo" %><br />
       <%= f.text_area :memo %>
     </p>
       <%= f.hidden_field :folder_id %>
 <p><%= f.submit "Upload" %></p>
<% end %>

Answer 1

I think a good counterquestion is "why should show an uploaded file by default?".
But basically is because security reasons and none of the browsers (yep, nothing to do with rails) is going to allow that, so you must to indicate manually to the user about the uploaded files.