Extending CodeIgniter’s Validation To Check For Unique

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');
/**
 * MY_Form_validation Class
 *
 * Extends Form_Validation library
 *
 * Adds one validation rule, "unique" and accepts a
 * parameter, the name of the table and column that
 * you are checking, specified in the forum table.column
 *
 * Note that this update should be used with the
 * form_validation library introduced in CI 2.0.2
 */

class MY_Form_validation extends CI_Form_validation {

    function __construct($config)
    {
        parent::__construct($config);
    }

    // --------------------------------------------------------------------

    /**
     * Unique
     *
     * @access  public
     * @param   string
     * @param   field
     * @return  bool
     */
function unique($str,$field)
    {
        $CI =& get_instance();
        $CI->load->database();
        list($table, $column) = split("\.", $field, 2);

        $CI->form_validation->set_message('unique', 'The %s that you requested is unavailable.');

        $query = $CI->db->query("SELECT $column FROM $table WHERE $column = '$str' limit 1");
        return ($query->num_rows() > 0) ? FALSE : TRUE;

/**
 *      $query = $CI->db->query("SELECT COUNT(*) AS dupe FROM $table WHERE $column = '$str'");
 *      $row = $query->row();
 *      return ($row->dupe > 0) ? FALSE : TRUE;
 */
    }
}
?>