unserialize --
Creates a PHP value from a stored representation
Description
mixed unserialize ( string str )
unserialize() takes a single serialized
variable (see serialize()) and converts it
back into a PHP value. The converted value is returned, and can
be a boolean, integer, float,
string, array or object.
In case the passed string is not unserializeable, FALSE is returned and
E_NOTICE is issued.
Warning
FALSE is returned both in the case of an error and if unserializing
the serialized FALSE value. This special case can be catched by
comparing str with
serialize(false) or by catching the issued
E_NOTICE.
unserialize_callback_func directive:
It's possible to set a callback-function which will be called,
if an undefined class should be instantiated during unserializing.
(to prevent getting an incomplete object "__PHP_Incomplete_Class".)
Use your php.ini, ini_set() or .htaccess
to define 'unserialize_callback_func'. Everytime an undefined class
should be instantiated, it'll be called. To disable this feature just
empty this setting. Also note that the directive
unserialize_callback_func directive became
available in PHP 4.2.0.
If the variable being unserialized is an object, after successfully
reconstructing the object PHP will automatically attempt to call the
__wakeup() member function (if it exists).
// unserialize_callback_func directive available as of PHP 4.2.0 ini_set('unserialize_callback_func', 'mycallback'); // set your callback_function
function mycallback($classname) { // just include a file containing your classdefinition // you get $classname to figure out which classdefinition is required } ?>
Note:
In PHP 3, methods are not preserved when unserializing a
serialized object. That limitation was removed in PHP 4 as both
properties and methods are now restored. Please see the Serializing Objects
section of Classes and
Objects or more information.
Example 2. unserialize() example
<?php // Here, we use unserialize() to load session data to the // $session_data array from the string selected from a database. // This example complements the one described with serialize().
$conn = odbc_connect("webdb", "php", "chicken"); $stmt = odbc_prepare($conn, "SELECT data FROM sessions WHERE id = ?"); $sqldata = array ($PHP_AUTH_USER); if (!odbc_execute($stmt, &$sqldata) || !odbc_fetch_into($stmt, &$tmp)) { // if the execute or fetch fails, initialize to empty array $session_data = array(); } else { // we should now have the serialized data in $tmp[0]. $session_data = unserialize($tmp[0]); if (!is_array($session_data)) { // something went wrong, initialize to empty array $session_data = array(); } } ?>
