php - codeigniter ajax form_validation (with jquery) -

i trying validate fields witj ajax through codeigniter, can't quite figure out how it "right".

my ajax:

var timeout = null;  $(document).ready(function(){      $('.new-user-box input').each(function(){          var key = $(this).attr('name');          $(this).on("keyup", function() {             var value = $(this).val();              if(value=="") {                 return false;             }              var json = {};             json[key] = value;             json['ajax'] = '1';              if (timeout) {                 cleartimeout(timeout);             }             timeout = settimeout( function() {                 $.ajax({                 url: 'auth/ajax_validate',                 type: 'post',                 data: json,                 success: function(data) {                     console.log(data);                 }                 })             }, 1000)         });      })  }) 

this lets input fields send value on keyup (after 1 second).

my php (just snippet username test):

<?php      function ajax_validate()     {          // test if method called ajax , validate input field         if($this->input->post('ajax'))         {             if($this->input->post('username'))             {                 if($this->form_validation->set_rules('username', 'brugernavn', 'required|trim|min_length[1]|max_length[20]|is_unique[users.username]|xss_clean') && !$this->form_validation->run())                 {                     $validates = 0;                 }                 else {                     $validates = 1;                     $error = "";                 }                 $response = array($validates,$form_error('username'));                 echo json_encode($response);                 exit;             }         }      }  ?> 

the response receive php error:

message: undefined variable: form_error

fatal error: function name must string in \path codeigniter\application\modules\auth\controllers\auth.php on line 401

hope has clue how fix this, or way. thankyou in advance.

take out $ before "form_error".

$response = array($validates,$form_error('username')); 

to

$response = array($validates,form_error('username'));