Drupal 7 Module Development

Chapter 5
This is all the information that is needed to register our path. Now when
Drupal receives a request for this URL, it will return the results of
drupal_get_form(user_warn_form).
Drupal caches the entire menu, so new/updated menu items will
not be reflected immediately. To manually clear the cache, visit
Admin | Configuration | Development | Performance and click
on Clear all caches.
Using wildcards in menu paths
We have created a simple menu item, but sometimes simple won't do the job. In
the User Warn module we want to have a menu item that is tied to each individual
user's profile page. Profile pages in Drupal live at the path user/, so how
do we create a distinct menu item for each user? Fortunately the menu system allows
us to use wildcards when we define our menu paths.
If you look at the second menu item defined in the preceding example, you will see
that its definition differs a bit from our first example.
$items['user/%/warn'] = array(
'title' => 'Warn',
'description' => 'Send e-mail to a user about improper site
behavior.',
'page callback' => 'drupal_get_form',
'page arguments' => array('user_warn_confirm_form', 1),
'access arguments' => array('administer users'),
'type' => MENU_LOCAL_TASK,
);
The first difference is that the path is defined with % as one of the path entries. This
indicates a wildcard; anything can be entered here and the menu item's hierarchy
will be maintained. In Drupal, that will always be a user's ID. However, there is
nothing stopping any user from entering a URL like user/xyzzy/warn or something
else potentially more malicious. Your code should always be written in such a way
as to handle these eventualities, for instance by verifying that the argument actually
maps to a Drupal user. This would be a good improvement.
The other difference in this example is that we have added 1 as an additional
argument to be passed to our page callback.
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