Rails paperclip, Edit form file_field not assigned

Question

I used paperclip to attach an avatar onto my user, in my Model:

has_attached_file :avatar, 
    :styles => {square_tiny: '50x50#', square_small: '100x100#', square: '200x200#'}

I have a form

<%= form_for(@user_profile, 
        :url => { :controller => :user_profiles, :action => :update_general_info, :id => @user_profile.id }, 
            :html => {  :multipart => true, 
                :class=> "form-horizontal" }) do |f| %>

            <div class="control-group">
              <%= f.label :avatar, :class => "control-label" %>
                <div class="controls">
                    <%= f.file_field :avatar  %>
                </div>
            </div>

....

<% end %>

The upload works perfect, but I come back and EDIT my user, the file field says 'no file chosen'. And since I am validating presence of that avatar, every time a user edit his details, he has to upload his avatar again...

How do I work around that?

I thought the :multipart => true would help but it didn't.

Answer 1

There is absolutely no good way for a page to set a value to a file field, and that's for security reasons.

If the browser allowed a page or a JS script to set a value to a file field that would allow a malicious page to preset the file field value with some system or passwords file. And that would be a massive security hole.

What I do in that case is I display the already saved file as a link that the user can click to download. You can then provide little AJAX links to delete (the file is deleted with an AJAX call and the link replaced with a new file input) and replace (the link is replaced with a file input).

Your last option would be to use AJAX to upload the file. If you use AJAX for a file upload you'll POST to a hidden frame so the file input will keep its selected value. Either way keep in mind that any change to file field value has to be user initiated.