PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

Reading Mail
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value="index.php?action=select-account&account=3">
localhost
Most of this code is just an HTML select element, but it also includes a little
JavaScript. In the same way that PHP can generate HTML, it can also be used to generate
client-side scripts.
Whenever a change event happens to this element, JavaScript sets window.location
to the value of the option. If your user selects the first option in the select,
window.location will be set to ‘index.php?action=select-account&account=10’.
This results in this URL being loaded. Obviously, if the user has a browser that does not
support JavaScript or has JavaScript disabled, this code will have no effect.
The display_account_select() function, from output_fns.php, gets the available
account list and displays the SELECT. It also uses the get_account_list() function discussed
previously.
Choosing one of the options in the SELECT activates the select_account event. If
you look at the URL in Figure 29.5, you can see this event appended to the end of the
URL, along with the account ID of the chosen account.
Appending these GET variables has two effects. First, in the preprocessing stage of
index.php, the chosen account is stored in the session variable $selected_account,as
follows:
case 'select-account':
// if have chosen a valid account, store it as a session variable
if(($account) && (account_exists($_SESSION['auth_user'],
$account))) {
$_SESSION['selected_account'] = $account;
}
break;
Second, when the body stage of the script is executed, the following code is executed:
case 'select-account':
case 'view-mailbox':
// if mailbox just chosen, or view mailbox chosen, show mailbox
display_list($_SESSION['auth_user'],
$_SESSION['selected_account']);
break;
As you can see, you take the same action here as if the user had chosen the View
Mailbox option.We look at that action next.