Additional form validation only after passing default validation

Question

In Drupal 6.25.

I am building a custom user registration form that needs to run some actions on an external service after properly passing default form validation but before creating a new user record in Drupal. So far I am doing the following:

function mbrusers_form_alter(&$form, &$form_state, $form_id){
   if($form_id == "user_register"){
       if($default_form_validation_passed){
           $form['#validate'][] = 'mbrusers_infusionConnect_validate';
       }
   }
}

function mbrusers_infusionConnect_validate($form, &$form_state){
    // Run actions on external service
    if($error){
        form_set_error("", "SET ERROR");
    }
}

I feel like I'm overlooking something, but I haven't been able to figure out what to do. Maybe using validate is the wrong idea? Any help that sets me in the right direction is appreciated.

Answer 1

You should be able to rearrange the order of multiple validation functions in the $form['#validate'] array. After ensuring that your function runs in the correct order, wrap your code acting on your service in an if statement checking for existing form errors using form_get_errors(), like so:

// Validation has already failed if prior functions return errors, so this is safe.
if (empty(form_get_errors())) {
  // Run calls on external service here...
  if($error){
    form_set_error("", "SET ERROR");
  }
}

Since you need to validate the response from your service, doing it in the validation phase makes the most sense.

Answer 2

I'm pretty sure you have to re-arrange the order of the validators, and inject yours basically in the middle instead of just adding it at the end.

From user.module, $form['#validate'] = user_login_default_validators(); or:

/**
 * Set up a series for validators which check for blocked/denied users,
 * then authenticate against local database, then return an error if
 * authentication fails. Distributed authentication modules are welcome
 * to use hook_form_alter() to change this series in order to
 * authenticate against their user database instead of the local users
 * table.
 *
 * We use three validators instead of one since external authentication
 * modules usually only need to alter the second validator.
 *
 * @see user_login_name_validate()
 * @see user_login_authenticate_validate()
 * @see user_login_final_validate()
 * @return array
 *   A simple list of validate functions.
 */
function user_login_default_validators() {
  return array('user_login_name_validate', 'user_login_authenticate_validate', 'user_login_final_validate');
}

and

/**
 * A validate handler on the login form. Check supplied username/password
 * against local users table. If successful, sets the global $user object.
 */
function user_login_authenticate_validate($form, &$form_state) {
  user_authenticate($form_state['values']);
}

so I'd do something like:

$form['#validate'] = array('user_login_name_validate', 'mbrusers_infusionConnect_validate', 'user_login_authenticate_validate', 'user_login_final_validate');

instead of if <Default form validation passed> so that your validation function is called before the normal/usual second validator.

Answer 3

Another way to achieve your functionality I reckon is to use hook_user and trap $op = 'insert' to do something before the user account is added to the Drupal database.