Creating a custom codeigniter validation rule

You use the callback_ in your rules, see callbacks, for ex.

$this->form_validation->set_rules('email_address', '"Email address"', 'trim|required|valid_email|callback_validate_member');

and add the method in the controller. This method needs to return either TRUE or FALSE

function validate_member($str){   $field_value = $str; //this is redundant, but it's to show you how   //the content of the fields gets automatically passed to the method   if($this->members_model->validate_member($field_value))   {     return TRUE;   }   else   {     return FALSE;   }}

You then need to create a corresponding error in case the validation fails

$this->form_validation->set_message('validate_member','Member is not valid!');

One best way to achieve this is extending CodeIgniter’s Form Validation library. Let say we want to create a custom validator named access_code_unique for the field access_code of the database table users.

All you have to do is creating a Class file named MY_Form_validation.php in application/libraries directory. The method should always return TRUE OR FALSE

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');class MY_Form_validation extends CI_Form_validation {    protected $CI;    public function __construct() {        parent::__construct();            // reference to the CodeIgniter super object        $this->CI =& get_instance();    }    public function access_code_unique($access_code, $table_name) {        $this->CI->form_validation->set_message('access_code_unique', $this->CI->lang->line('access_code_invalid'));        $where = array (            'access_code' => $access_code        );        $query = $this->CI->db->limit(1)->get_where($table_name, $where);        return $query->num_rows() === 0;    }}

Now you can easily add your new created rule

$this->form_validation->set_rules('access_code', $this->lang->line('access_code'), 'trim|xss_clean|access_code_unique[users]');