JsonSerializable::jsonSerialize

(PHP 5 >= 5.4.0, PHP 7)

JsonSerializable::jsonSerialize — 指定需要被序列化成 JSON 的数据

说明

abstract public mixed JsonSerializable::jsonSerialize ( void )

序列化物体（Object）成能被 json_encode() 原生地序列化的值。

参数

此函数没有参数。

返回值

返回能被 json_encode() 序列化的数据，这个值可以是除了 resource 外的任意类型。

范例

Example #1 JsonSerializable::jsonSerialize() 例子 returning an array

  <?php
 class  ArrayValue  implements  JsonSerializable  {
    public function  __construct (array  $array ) {
         $this -> array  =  $array ;
    }

    public function  jsonSerialize () {
        return  $this -> array ;
    }
}

 $array  = [ 1 ,  2 ,  3 ];
echo  json_encode (new  ArrayValue ( $array ),  JSON_PRETTY_PRINT );
 ?>

以上例程会输出：

Example #2 JsonSerializable::jsonSerialize() 例子返回了一个关联数组 array

  <?php
 class  ArrayValue  implements  JsonSerializable  {
    public function  __construct (array  $array ) {
         $this -> array  =  $array ;
    }

    public function  jsonSerialize () {
        return  $this -> array ;
    }
}

 $array  = [ 'foo'  =>  'bar' ,  'quux'  =>  'baz' ];
echo  json_encode (new  ArrayValue ( $array ),  JSON_PRETTY_PRINT );
 ?>

以上例程会输出：

{
    "foo": "bar",
    "quux": "baz"
}

Example #3 JsonSerializable::jsonSerialize() 例子返回一个 integer

  <?php
 class  IntegerValue  implements  JsonSerializable  {
    public function  __construct ( $number ) {
         $this -> number  = (integer)  $number ;
    }

    public function  jsonSerialize () {
        return  $this -> number ;
    }
}

echo  json_encode (new  IntegerValue ( 1 ),  JSON_PRETTY_PRINT );
 ?>

以上例程会输出：

Example #4 JsonSerializable::jsonSerialize() 例子返回一个 string

  <?php
 class  StringValue  implements  JsonSerializable  {
    public function  __construct ( $string ) {
         $this -> string  = (string)  $string ;
    }

    public function  jsonSerialize () {
        return  $this -> string ;
    }
}

echo  json_encode (new  StringValue ( 'Hello!' ),  JSON_PRETTY_PRINT );
 ?>

以上例程会输出：

"Hello!"

用户评论:

[#1] david at vanlaatum dot id dot au [2015-04-02 02:57:43]

simonsimcity at gmail dot com is wrong, you can throw exceptions in this but it will wrap with another exception so his example outputs

PHP Fatal error: Uncaught exception 'RuntimeException' with message 'It failed!' in -:8
Stack trace:
#0 [internal function]: Foo->jsonSerialize()
#1 -(16): json_encode(Object(Foo))
#2 {main}

Next exception 'Exception' with message 'Failed calling Foo::jsonSerialize()' in -:16
Stack trace:
#0 -(0): json_encode()
#1 {main}
thrown in - on line 16

PHP 5.4.39

[#2] Anonymous [2015-01-23 18:34:50]

Serialize private attributes to JSON in PHP 5.3

<?php abstract class Model { public function jsonSerialize() { $getter_names = get_class_methods(get_class($this)); $gettable_attributes = array(); foreach ($getter_names as $key => $value) { if(substr($value, 0, 4) === 'get_') { $gettable_attributes[substr($value, 4, strlen($value))] = $this->$value(); } } return $gettable_attributes; } } class Content extends Model { private $title; private $text; public function get_title() { return $this->title; } public function set_title($title) { $this->title = $title; } public function get_text() { return $this->text; } public function set_text($text) { $this->text = $text; } } $content = new Content(); $content->set_title('lol'); $content->set_text('haha'); echo json_encode($content->jsonSerialize()); ?>

[#3] dimstefan83 at gmail dot com [2014-06-20 08:34:50]

simple functions to make life easier.
I wanted a way to have a as property value the return value of a method in order to have it initialized. example

class portItem implements JsonSerializable{
private $idPort;
private $location;
private $portLanguages;

public function getLocation() {
if(!isset($this->location)){
return new locationItem();
}
return $this->location;
}

public function setLocation($location) {
$this->location = $location;
}

      public function setidPort($idPort){
$this->idPort=$idPort;
}

public function getidPort(){
if(!isset($this->idPort)){
return 0;
}
return intval($this->idPort);
}
public function setPortLanguages($portLanguages){
$this->portLanguages=$portLanguages;
}

public function getPortLanguages(){
if(!isset($this->portLanguages)){
return new genericItems();
}
return $this->portLanguages;
}

public function getCategoryLanguages(){
if(!isset($this->portLanguages)){
return new genericItems();
}
return $this->portLanguages;
}

public function getPortLanguageAtIndex($index=false){
if(!$index){
$index=0;
}
return $this->portLanguages[$index];
}

public function setPortLanguageAtIndex($index,$language){
$this->portLanguages[$index]=$language;
}

        public function jsonSerialize() {
$dataConverter = new dataConverter();
return $dataConverter->convertToJson($this);
}

}

Wit 2 ways you can automatically convert for json.
1.by reading properties
public function convertToJson($object){

$class = get_class($this);
$json = array();
$properties = get_class_vars($class);
$keys = array_keys($properties);
$plength = count($keys);
for($i=0;$i<$plength;$i++){
$method =  "get".$keys[$i];
if(method_exists ($this,$method)){
$json[$keys[$i]] = $this->$method();
}
}
return $json;
}

public function convertToJson($object){

$class = get_class($object);
$json = array();
$methods = get_class_methods($class);
$plength = count($methods);
$json = array();
for($i=0;$i<$plength;$i++){
if(stripos($methods[$i], "get")!==FALSE){
$property = mb_substr($methods[$i], 3,mb_strlen($methods[$i],'UTF-8'),'UTF-8');
$setter = "set".mb_substr($methods[$i], 3,mb_strlen($methods[$i],'UTF-8'),'UTF-8');
if(method_exists($object,$setter)){
$json[$property] = $object->$methods[$i]();
}

}
}

return $json;
}

By using this method the result will be a json with value for properties initialized according to each method.

Things to note
1.if you are using the reading properties approach the code cant' work outside of the class for private properties, because they are nto visible, you have to put it the code directly to public function jsonSerialize() {} in order to work.
2.For both approaches has method seems not to be case sensitive else you are going to have problems, i strongly suggest to pay attention in naming convention between property names and method names idPort =>setIdPort() =>getIdPort() (i know my class is done not that way).
3.both approaches since you call method without knowing the arguments you need to pay attention in arguments for getter methods where applicable, check my example
public function getPortLanguageAtIndex($index=false){
if(!$index){
$index=0;
}
return $this->portLanguages[$index];
}
that's why i have set it to optional argument. If you don't do that php will complain about missing argument parameter in method XXX.

[#4] simonsimcity at gmail dot com [2014-03-22 11:05:17]

You can't throw exceptions in here. If you do, you'll get an exception with the message "Failed calling FooClass::jsonSerialize()" and the stacktrace will start at where you called the json_encode() method.

Here's a code-example:

class Foo implements JsonSerializable {
    private $triggerError = true;

    public function jsonSerialize()
    {
        if ($this->triggerError) {
            throw new RuntimeException("It failed!");
        }

        return (array)$this;
    }
}

// Will throw an exception like new Exception("Failed calling Foo::jsonSerialize()")
json_encode(new Foo());

[#5] benkuhl at gmail dot com [2013-01-31 16:17:40]

A good example on when you would use functionality like this is when working with objects.

json_encode() will take a DateTime and convert it to:

{
    "date":"2013-01-31 11:14:05",
    "timezone_type":3,
    "timezone":"America\/Los_Angeles"
}

This is great when working with PHP, but if the Date is being read by Java.  The Java date parser doesn't know what to do with that.  But it does know what to do with the ISO8601 format...

<?php date_default_timezone_set('America/Los_Angeles'); class Fruit implements JsonSerializable {     public         $type = 'Apple',         $lastEaten = null;     public function __construct() {         $this->lastEaten = new DateTime();     }     public function jsonSerialize() {         return [             'type' => $this->type,             'lastEaten' => $this->lastEaten->format(DateTime::ISO8601)         ];     } } echo json_encode(new Fruit()); //which outputs: {"type":"Apple","lastEaten":"2013-01-31T11:17:07-0500"} ?>