Hook into Drupal registration and validate user info against business logic

Question

I want to hook into the registration module. I already have a database of 50000 users who use my old website. Now I am migrating to Drupal.

I still haven\'t migrated the

Answer 1

You should register an additional validation callback function for the registration form using hook_form_FORM_ID_alter(), somewhat like so:

// Alter the registration form
function yourModuleName_form_user_register_alter(&$form, &$form_state) {
  // Add your own function to the array of validation callbacks
  $form['#validate'][] = 'yourModuleName_user_register_validate';
}

// Perform your own validation
function yourModuleName_user_register_validate($form, &$form_state) {
  // Extract the submitted name
  $name = $form_state['values']['name'];
  // Check it according to your own logic
  $is_valid_name = your_check_for_valid_name();
  // File error, when not valid
  if (!$is_valid) {
    form_set_error('name', t('Name already taken, please choose a different one'));
  }
}