Codeigniter - My form validation callback doesn't work

Question

I have tried to copy from Codegniter's documentation, but I can't make form validation callbacks working.

I added helper form, url and library form_validation. It's not working and always returns "false"

Controller

 public function addtest()
        {
            $this->load->helper(array('form', 'url'));

            $this->load->library('form_validation');

            $this->form_validation->set_rules('username', 'Username', 'callback_username_check');
            if($_SERVER['REQUEST_METHOD'] == 'POST')
            {
                 if ($this->form_validation->run() == TRUE)
                {
                       die('true');
                }
                else
                {
                       die('false');
                }
            }

            $this->template
                ->build('myform',array());
        }

    public function username_check($str)
    {
        if ($str == 'test')
    {
            return TRUE;
    }
    else
    {
            return FALSE;
    }
    }

View

<form method="post" action="" class="form-horizontal form-label-left">
    <div class="col-xs-12 col-md-9">
        <div class="x_panel">
            <div class="form-group col-xs-12">
                <div class="col-xs-3">
                    <label class="control-label">Folder name</label>
                </div>
                <div class="col-xs-9">
                    <input type="text" name="username" value="" class="form-control " id="" placeholder="">
                </div>
            </div>
            <button type="submit" class="btn btn-success">Submit</button>
        </div>
    </div>
</form>

Answer 1

In HTML (Add ID field)

<input type="text" name="username" value="" class="form-control " id="username" placeholder="">

<button type="submit" class="btn btn-success" id="submit">Submit</button>

In your AJAX code

<script type="text/javascript">
    $(function(){
        $( "#submit" ).click(function(event)
        {
            event.preventDefault();
            var username= $("#username").username();

            $.ajax(
                {
                    type:"post",
                    url: "<?php echo base_url(); ?>index.php/controller/Method",
                    data:{ username:username},
                    success:function(res)
                    {
                        
                    }
                });
        });
    });
</script>>

In Controller

No need of check if($_SERVER['REQUEST_METHOD'] == 'POST') because it comes through it always

public function addtest()
{
    $this->load->helper(array('form', 'url'));

    $this->load->library('form_validation');

    $this->form_validation->set_rules('username', 'Username', 'callback_username_check');

        if ($this->form_validation->run() == TRUE)
        {
            die('true');
        }
        else
        {
            die('false');
        }

    $this->template->build('myform',array());
}


public function username_check($str)
{
    if (empty($str)) 
    {
        echo "Empty";
    } 
    else 
    {
        if ($str == 'test')
        {
            return TRUE;
        }
        else
        {
            return FALSE;
        }
    }
}

Check more about CodeIgniter callback function

Answer 2

My Controller function is like this and it runs perfectly. I have autoloaded all libraries

public function change_password()
{
    if($this->isLoggedin()){
        $data['title']='Change Password';
        if($_POST)
        {
            $config=array(
                array(
                    'field' => 'old_password',
                    'label' => 'Old Password',
                    'rules' => 'trim|required|callback_checkPassword'
                ),
                array(
                    'field' => 'password',
                    'label' => 'Password',
                    'rules' => 'trim|required'
                ),
                array(
                    'field' => 'conf_password',
                    'label' => 'Confirm Password',
                    'rules' => 'trim|required|matches[password]'
                )
            );
            $this->form_validation->set_rules($config);
            if ($this->form_validation->run() == false)
            {
                // if validation has errors, save those errors in variable and send it to view
                $data['errors'] = validation_errors();
                $this->load->view('change_password',$data);
            }
            else
            {
                // if validation passes, check for user credentials from database
                $this->Login_model->updatePassword($_POST['password'],$this->session->userdata['id']);
                $this->session->set_flashdata('log_success','Congratulations! Password Changed');
                redirect(base_url() . 'Login/dashboard');
            }

        }
        else
        {
            $this->load->view('change_password',$data);
        }
    }
    else
    {
        redirect(base_url().'Login');
    }

}

public function checkPassword($str)
{
    $check=$this->Login_model->checkPassword($str);
    if($check)
    {
        return true;
    }
    else
    {
        $this->form_validation->set_message('checkPassword', 'The Current Password you have provided is incorrect');
        return false;
    }
}

Answer 3

Extend your form_validation library in Libraries.php

MY_Form_validation.php

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

class MY_Form_validation extends CI_Form_validation
{
    function run($module = '', $group = '') {

        (is_object($module)) AND $this->CI =& $module;
        return parent::run($group);
    }
}
/* End of file MY_Form_validation.php */
/* Location: ./application/libraries/MY_Form_validation.php */