Das Serializable-Interface

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

Einführung

Interface für benutzerdefiniertes Serialisieren.

Die Klassen, die dieses Interface implementieren, unterstützen __sleep und __wakeup nicht mehr. Die Methode serialize wird immer aufgerufen, wenn eine Instanz serialisiert werden muss. Dabei wird weder __destruct() aufgerufen noch irgend ein anderer Nebeneffekt erzeugt, es sei denn, ein solcher wird in der Methode serialize explizit erzeugt. Wenn die Daten deserialisiert werden, ist die Klasse bekannt und die passende unserialize()-Methode wird anstelle des Konstruktors __construct() aufgerufen. Falls notwendig, kann der Standardkonstruktor innerhalb von unserialize() aufgerufen werden.

Warnung

Seit PHP 8.1.0 erzeugt eine Klasse, die Serializable implementiert, ohne gleichzeitig auch __serialize() und __unserialize() zu implementieren, eine Deprecated- (veraltet) Warnung.

Interface-Übersicht

interface Serializable {
/* Methoden */
public serialize(): ?string
public unserialize(string $data): void
}

Beispiele

Beispiel #1 Grundlegende Verwendung

<?php
class obj implements Serializable {
private
$data;
public function
__construct() {
$this->data = "Meine private-Daten";
}
public function
serialize() {
return
serialize($this->data);
}
public function
unserialize($data) {
$this->data = unserialize($data);
}
public function
getData() {
return
$this->data;
}
}

$obj = new obj;
$ser = serialize($obj);

var_dump($ser);

$newobj = unserialize($ser);

var_dump($newobj->getData());
?>

Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:

string(42) "C:3:"obj":27:{s:19:"Meine private-Daten";}"
string(19) "Meine private-Daten"

Inhaltsverzeichnis

add a note

User Contributed Notes 4 notes

up
85
grzeniufication
8 years ago
Here's an example how to un-, serialize more than one property:

class Example implements \Serializable
{
protected $property1;
protected $property2;
protected $property3;

public function __construct($property1, $property2, $property3)
{
$this->property1 = $property1;
$this->property2 = $property2;
$this->property3 = $property3;
}

public function serialize()
{
return serialize([
$this->property1,
$this->property2,
$this->property3,
]);
}

public function unserialize($data)
{
list(
$this->property1,
$this->property2,
$this->property3
) = unserialize($data);
}

}
up
12
shaun at slickdesign dot com dot au
6 years ago
Serialized strings differ between instances that implement Serializable and those that don't.

Instances that don't implement Serializable use the Object notation "O:" when serialized, while those that do use the Class notation "C:". Class notation can only be used to unserialize instances that implement Serializable, while the Object notation can be used to unserialize any object.

Because of this, it is sometimes useful to implement the __wakeup() function when implementing Serializable, for instances where you may have a copy of the serialised class before it implemented Serializable (backwards compatible), or when you're expecting a serialized object from an external source, and they use Object notation for maximum compatibility. You can also use __wakeup() to process your unserialize function, or use it to help prevent people trying to bypass your unserialize.

Below is an example of a simple class hierarchy, where A is a standard class, B implements Serializable, and C uses __wakeup() to assist with unserializing it.

<?php
class A {
protected
$readonly_data = true;
public
$public_data = true;

public function
__construct( $data = true ) {
$this->public_data = $data;
}

public function
get_readonly_data() {
return
$this->readonly_data;
}
}

$a = new A;

var_dump( $a );
//object(A)#1 (2) {
// ["readonly_data":protected]=>
// bool(true)
// ["public_data"]=>
// bool(true)
//}
var_dump( serialize( $a ) );
//string(63) "O:1:"A":2:{s:16:"*readonly_data";b:1;s:11:"public_data";b:1;}"
?>
Class A outputs the following object, and its serialized string uses the object notation "O:". Please note that there is a null byte "\0" either side of the star*.

Changing the serialised string and unserializing it can cause protected and private values to change.
<?php
var_dump
( unserialize( "O:1:\"A\":2:{s:16:\"\0*\0readonly_data\";b:0;s:11:\"public_data\";b:0;}" ) );
//object(A)#1 (2) {
// ["readonly_data":protected]=>
// bool(false)
// ["public_data"]=>
// bool(false)
//}
?>

Class B extends A, and so has the same constructor and properties. It also implements Serializable.
<?php
class B extends A implements Serializable {
public function
serialize() {
return
serialize( $this->public_data );
}

public function
unserialize( $data ) {
$this->public_data = unserialize ( $data );
do_extra_processing_here();
}
}

$b = new B;

var_dump( serialize( $b ) );
// C:1:"B":4:{b:1;}
?>
As well as being a lot shorter, the serialized string uses the Class notation "C:", but you can still unserialize it using the older style notation. Doing this however will completely ignore the unserialize() function, potentially update the wrong information, and the function do_extra_processing_here() from the example above is not called.
<?php
var_dump
( unserialize( "O:1:\"B\":2:{s:16:\"\0*\0readonly_data\";b:0;s:11:\"public_data\";b:0;}" ) );
//object(B)#1 (2) {
// ["readonly_data":protected]=>
// bool(false)
// ["public_data"]=>
// bool(false)
//}
?>

Class C extends B, so it's already using the serialize() and unserialize() functions. By implementing the __wakeup() method, we ensure that we are validating the information and performing our do_extra_processing_here() function.
<?php
class C extends B {
public function
__wakeup() {
$new = new static;
$this->readonly_data = $new->get_readonly_data();
do_extra_processing_here();
}
}

var_dump( unserialize( "O:1:\"C\":2:{s:16:\"\0*\0readonly_data\";b:0;s:11:\"public_data\";b:0;}" ) );
//object(B)#1 (2) {
// ["readonly_data":protected]=>
// bool(true)
// ["public_data"]=>
// bool(false)
//}
?>
We can use __wakeup() to revert our readonly data back to what it was, or to add additional processing. You can additionally call __wakeup() from within unserialize() if you need to do the same process regardless of which serialized string notation was used.
up
8
info at ensostudio dot ru
4 years ago
Note: that interface declared as "deprecated" in PHP 7.4, use magic methods __serialize() and __unserialize() instead .
up
2
marcos dot gottardi at folha dot REM0VE-THIS dot com dot br
12 years ago
Serializing child and parent classes:

<?php
class MyClass implements Serializable {
private
$data;

public function
__construct($data) {
$this->data = $data;
}

public function
getData() {
return
$this->data;
}

public function
serialize() {
echo
"Serializing MyClass...\n";
return
serialize($this->data);
}

public function
unserialize($data) {
echo
"Unserializing MyClass...\n";
$this->data = unserialize($data);
}
}

class
MyChildClass extends MyClass {
private
$id;
private
$name;

public function
__construct($id, $name, $data) {
parent::__construct($data);
$this->id = $id;
$this->name = $name;
}

public function
serialize() {
echo
"Serializing MyChildClass...\n";
return
serialize(
array(
'id' => $this->id,
'name' => $this->name,
'parentData' => parent::serialize()
)
);
}

public function
unserialize($data) {
echo
"Unserializing MyChildClass...\n";
$data = unserialize($data);

$this->id = $data['id'];
$this->name = $data['name'];
parent::unserialize($data['parentData']);
}

public function
getId() {
return
$this->id;
}

public function
getName() {
return
$this->name;
}
}

$obj = new MyChildClass(15, 'My class name', 'My data');

$serial = serialize($obj);
$newObject = unserialize($serial);

echo
$newObject->getId() . PHP_EOL;
echo
$newObject->getName() . PHP_EOL;
echo
$newObject->getData() . PHP_EOL;

?>

This will output:

Serializing MyChildClass...
Serializing MyClass...
Unserializing MyChildClass...
Unserializing MyClass...
15
My class name
My data
To Top