Question

In Drupal 6 you could use code similar to the following one:

function example_user($op, &$edit, &$account, $category = NULL) {
  switch($op) {
    case 'load':
      $account->fb_id ='xyz'
      break;
  }
}

In Drupal 7, the documentation for hook_user_load() states the following:

Due to the static cache in user_load_multiple() you should not use this hook to modify the user properties returned by the {users} table itself since this may result in unreliable results when loading from cache.

Why do I get users and not just a user?

Is it ok to add properties to this?

http://api.drupal.org/api/drupal/modules–user–user.api.php/function/hook_user_load/7

Answer 1

You get an array of user objects because the hook is called from user_load_multiple(), which generally calls DrupalDefaultEntityController::load(), which then calls DrupalDefaultEntityController::attachLoad().

It is fine to add custom properties, but not to override the default properties that are loaded from the {users} table; as reported from the documentation, in that case you could get some problem when loading the user object from the cache, which is what the entity API normally does.