Validation messages and $.parseJSON(xhr.responseText).errors

Rails
1

Hello!

I try to catch a validation message with a
$.parseJSON(xhr.responseText).errors but an alert message hows me
“undefined” and I do not understand why.

hier are my validations:

validates :upload_file_name,  :presence   => true,
                                :format     =>{:with =>

%r{.(jpg)$}i,:message =>“It should be a pdf File”}

  validates_uniqueness_of :upload_file_name, :message => "blabla"

  validates :upload_file_size,  :inclusion  => {:in

=>1.megabytes…20.megabytes,:message=>“bla”}

json:

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

:status =>422}

and javascript for that:

 $('#fileupload').fileupload({


        error: function(xhr){
          var errors = $.parseJSON(xhr.responseText).errors
          alert(errors)
        }
              });

Thanks in advanced