JsonSerializable::jsonSerialize

(PHP 5 >= 5.4.0, PHP 7)

JsonSerializable::jsonSerialize — Specify data which should be serialized to JSON

Description

abstract public mixed JsonSerializable::jsonSerialize ( void )

Serializes the object to a value that can be serialized natively by json_encode().

Parameters

This function has no parameters.

Return Values

Returns data which can be serialized by json_encode(), which is a value of any type other than a resource.

Examples

Example #1 JsonSerializable::jsonSerialize() example 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);
?>

The above example will output:

Example #2 JsonSerializable::jsonSerialize() example returning an associative 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);
?>

The above example will output:

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

Example #3 JsonSerializable::jsonSerialize() example returning an 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);
?>

The above example will output:

Example #4 JsonSerializable::jsonSerialize() example returning a 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);
?>

The above example will output:

"Hello!"

User Contributed Notes

benkuhl at gmail dot com

3 years ago


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"}

?>

david at vanlaatum dot id dot au

1 year ago


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

Anonymous

1 year ago


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());
?>

simonsimcity at gmail dot com

2 years ago


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());

dimstefan83 at gmail dot com

1 year ago


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){
        /*approch by using object properties*/
        $class = get_class($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){     
/*approch by using object methods*/
        $class = get_class($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.