I have seen this question all over the web and am surprised that nobody has actually offered such a simple solution.

Anyway, here is a quick, simple and painless way to set CodeIgniter’s error delimiters (used by the Form_validation library) one time for your entire application. Create “application/libraries/MY_Form_validation.php” with the following contents…

class MY_Form_validation extends CI_Form_validation {
    public function __construct()
    {
        parent::__construct();
        $this->_error_prefix    = '<div class="ui-widget"><div class="ui-state-error ui-corner-all" style="display: inline-block; padding: 2px 4px"><span style="float: left; margin-right: 2px"></span> ';
        $this->_error_suffix    = '</div></div>';
    }
}

No more setting the delimiters every time you load the Form_validation library!

You can still override the new delimiters by using
$this->form_validation->set_error_delimiters()
in your controllers as needed.

Note: If you’re curious about the HTML I used above, it was adapted from the jQueryUI – Themeroller page source.