How can I associate error messages to the 'error' key in json response

[akvarel]

I am trying to show the errors that can occur by uploading a file (file name, size).
I am using an adapted version of Jquery Fiel Upload for Ruby on Rails

I need to have my error messages (validations) associated to the 'error' key in my json response.

I guess I have to change the javascript to make it work.


json:

 render json: {error: @upload.errors.full_messages}, status: :unprocessable_entity

validations:

     validates_uniqueness_of :upload_file_name, :message => "File with this name is already in the database"
         
     validates :upload_file_size,  :inclusion  => {:in =>10.megabytes..20.megabytes}, :message =>"Too big or too small"

Javascript I use to upload the files:

<script type="text/javascript" charset="utf-8">
          $(function () {
              // Initialize the jQuery File Upload widget:
              $('#fileupload').fileupload();
              // 
              // Load existing files:
              $.getJSON($('#fileupload').prop('action'), function (files) {
                var fu = $('#fileupload').data('fileupload'), 
                  template;
                fu._adjustMaxNumberOfFiles(-files.length);
                console.log(files);
                template = fu._renderDownload(files)
                  .appendTo($('#fileupload .files'));
                // Force reflow:
                fu._reflow = fu._transition && template.length &&
                  template[0].offsetWidth;
                template.addClass('in');
                $('#loading').remove();
              });
        
          });
        </script>

I have tried as well those things:
`json: => [{:error=> @upload.errors.full_messages }] }`
using this shows only the validation message but I need the status: as well

I was suggested as well to do this way. But I dont have a js.file, the only javascript I have is in the index.html.erb and you can see it above.

render :json => { :errors => @example.errors.full_messages }, :status => 422

in your js file:

$('.form_id_or_class').live('submit', function() {
      $.ajax({
        url: $(this).attr("action"),
          type: "POST",
          data: $(this).serialize(),
          success: function(data) {
           // do some action
        }
        ,error: function(xhr){
          var errors = $.parseJSON(xhr.responseText).errors
        }
      });
      return false;
    });

Many thanks in advanced