CodeIgniter Form Validation - callback not bound to a field

Is there a way to set a validation callback that is not b开发者_JAVA技巧ound to a particular field, but is necessary to pass validation?

Yes you can and here is a cruddy example:

$this->load->library('form_validation');
$this->form_validation->set_rules('username', 'lang:lang_username', 'required|callback_check_login');

Then for the callback:

public function check_login($username)
{
    $username = $this->input->post('username');
    $password = $this->input->post('password');
    $remember = $this->input->post('remember');

    $login = $this->users_auth->login($username, $password, $remember);
    if ($login !== TRUE)
    {
        $this->form_validation->set_message('check_login', $login);
        return FALSE;
    }
    else
    {
        return TRUE;
    }
}

Add a hidden field to your form and assign the callback to that a field. The callback doesn't have to relate to the contents of the hidden field.

Edit: Or, for that matter, you could assign the callback to any of your fields along other validation rules. No need for a hidden field.