__sleep and __wakeup in php

In php, __sleep and ___wakeup are two methods that are called before and after object serialization.
Among them, __sleep is called before an object is serialized. It does not receive any parameters, but will return an array. Here you can Place which attributes need to be serialized, such as the following example:

class Customer {
 private $name;
 private $credit_card_number; 
 
public function setName($name) {
 $this->name = $name;
 }
 
public function getName() {
 return $this->name;
 }
 
public function setCC($cc) {
 $this->credit_card_number = $cc;
 }
 
public function getCC() {
 return $this->credit_card_number;
 }
 
public function __sleep() {
 return array(“name”); //只有name会序列化 }
 
}
 
$c = new Customer();
 $c->setName(“Stuard”);
 $c->setCC(“456789″);
 
$data = serialize($c).”\n”;
 echo $data.”\n”;
 
Output:
 O:8:”Customer”:1:{s:14:” Customer name”;s:5:”Stuard”;}

Before serialization above, __sleep specified that only the name attribute will be serialized, but creaditcard will not.

On the contrary, __wakeup is triggered before deserialization, such as the following example:

class Customer {
 private $name;
 private $credit_card_number; 
 
public function setName($name) {
 $this->name = $name;
 }
 
public function getName() {
 return $this->name;
 }
 
public function setCC($cc) {
 $this->credit_card_number = $cc;
 }
 
public function getCC() {
 return $this->credit_card_number;
 }
 
public function __sleep() {
 return array(“name”);
 }
 
public function __wakeup() {
 if($this->name == “Stuart”) {
  //重新在数据库中获得 
 $this->credit_card_number = “1234567890123456″;
 }
 }
 }
 
$c = new Customer();
 $c->setName(“Stuart”);
 $c->setCC(“1234567890123456″);
 
$data = serialize($c).”\n”;
 var_dump(unserialize($data));
 
Output:
 object(Customer)#2 (2) {
 ["name:private"]=>
 string(5) “Stuart”
 ["credit_card_number:private"]=>
 string(16) ’1234567890123456³
 }

In the above code, because __sleep is used during serialization, the creadit cardnumber attribute is not serialized, so it is Before calling unserialize, the __wakeup method will be called first. For example, here you can re-obtain the data in the database and then perform the operation