Drupal 7 Module Development

Building an Admin Interface
Drupal also offers several custom form elements in addition to the standard HTML
fields. You can see an example of one of these in the drupal_get_form() callback
for our second menu item:
/**
* Form builder; display the e-mail confirmation form.
*/
function user_warn_confirm_form($form, &$form_state, $uid) {
$form['account'] = array(
'#type' => 'value',
'#value' => user_load($uid),
);
}
return confirm_form(
$form,
t('Are you sure you want to send a warning e-mail to this
user?'),
'user/' . $uid,
t('This action can not be undone.'),
t('Send e-mail'),
t('Cancel')
);
We will revisit this function in more detail later in the chapter, but for now we will
focus on the highlighted area. As you'll remember from earlier in this chapter, we
used a wildcard in the menu item path to grab the user's ID and pass it into the page
callback. As you can see now, this is being passed as the third parameter into our
callback function (after the required $form and $form_state parameters). We can
now use this ID to retrieve data about the user for future use.
Also, you can see that we are defining a new form element of type 'value'. The
value element is similar to the HTML hidden fields with two distinct advantages.
First, value elements can contain any data you want as opposed to just strings.
Arrays, objects, or any other complex data structure can be stored and passed in a
value element.
The second advantage is that value elements are not printed back to the browser in
the HTML source. This can improve the security of your data by preventing users
from viewing and/or modifying it on a local instance.
In this code sample we are assigning the value element 'account' with the value of
a Drupal user object. This object will be passed on when the form is submitted, and
the receiving function will be able to use it as needed. Value elements are extremely
useful and developers should always consider using them in places where they
would otherwise use hidden fields.
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