Global $user object isn't always "Fully Loaded"

Question

I have a Drupal 6 module that implements hook_user() to add a custom property on op='load';

mymodule_user($op, &$edit, &$account, $category = NULL) {
  $account->external_id = mymodule_get_user_external_id($account->uid);
}

In modules, I access the global $user object. What I find is sometimes it has my ->external_id property, and sometimes it doesn't.

As a result, I end up having to check to see if my custom property is set, and if not, call user_load()

if(isset($GLOBALS['user']->external_id)) {
  $account = $GLOBALS['user'];
} else {
  $account = user_load($GLOBALS['user']->uid);
}

Yuck! Is this a known problem, or does it sound like I'm doing something wrong?

Answer 1

Nope, you are doing it right as this is a known issue/behavior. Check out http://api.drupal.org/api/drupal/developer%21globals.php/global/user/6 for a lot more information on it. A link from there, http://drupal.org/node/57287, talks to your point directly (it is for D7 but is germaine to D6).

Answer 2

With the user hooks, a general rule of thumb is that when the parameter in the API is specified as $account, don't expect it to be interchangeable with $user. So, in your case, doing a user_load() to explicitly load the extra information is appropriate and needed. hook_node_access in Drupal 7 is another example that does this. A similar thing happens with fieldable entities with some hooks, where not all of the fields are present in the argument passed into a hook.

There is an answer on the main SO site that goes into this topic in more detail. There is also a related issue on drupal.org about it, too.