Form Validation Call Back Function Not Working - php

Question

Here Is My COde I m checking username is already exist or not in datbase
when i validate and submit the form duplicate entry entered in database i want that if already exist it show validation error
My Controller
public function index()
{
if($this->input->post('submit')) {
$this->form_validation->set_rules('name', 'User Name', 'callback_checkuser');
$this->form_validation->set_rules('role', 'Role', 'trim|required');
$this->form_validation->set_rules('pass', 'Password', 'trim|required');
if($this->form_validation->run()==TRUE)
{
$user['u_name'] = $this->input->post('name');
$user['role'] = $this->input->post('role');
$user['password']= md5($this->input->post('pass'));
$u_id = $this->custom_model->add_user($user);
if($u_id){
$data['msg'] = 'Successfully Created!!!!';
}
}
}
$this->load->template('add_user', $data);
}
function checkuser($name) {
if($this->custom_model->check_name($name) == false) {
false;
}else {
$this->form_validation->set_message('checkuser', 'This user already exist');
return true;
}
}
Here is My Model
public function check_name($name) {
$sql = "SELECT * FROM users WHERE u_name='".$name."' ";
$query = $this->db->query($sql);
$res = $query->row_array();
if (is_array($res) && count($res) > 0){
return $res;
}
return false;
}

Answer 1

There is a return statement missing in the function checkuser, but more importantly, you should invert the value you return. According to the example in the docs, when you set a validation message because of a validation error, you should return false, and return true when the validation passes.
So add a return, and change the boolean values. BTW, you don't really need an else clause and the word "exist" needs an additional "s":
function checkuser($name) {
if ($this->custom_model->check_name($name) == false) {
return true; // the user does not yet exist, so all is OK
}
$this->form_validation->set_message('checkuser', 'This user already exists');
return false; // this is a duplicate user name: not OK
}

Answer 2

Use this:
$this->form_validation->set_rules('name', 'User Name', 'trim|required|is_unique[users.u_name]');// trim and required added too
Docs.