ConFoo 2025

JsonSerializable::jsonSerialize

(PHP 5 >= 5.4.0, PHP 7, PHP 8)

JsonSerializable::jsonSerializeEspecifica los datos que deberían serializarse para JSON

Descripción

abstract public JsonSerializable::jsonSerialize(): mixed

Serializa el objeto a un valor que puede ser serializado de forma nativa por json_encode().

Parámetros

Esta función no tiene parámetros.

Valores devueltos

Devuelve los datos que pueden ser serializados por json_encode(), los cuales son un valor de cualquier tipo distinto de resource.

Ejemplos

Ejemplo #1 Ejemplo de JsonSerializable::jsonSerialize() devolviendo un 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);
?>

El resultado del ejemplo sería:

[
    1,
    2,
    3
]

Ejemplo #2 Ejemplo de JsonSerializable::jsonSerialize() devolviendo un array asociativo

<?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);
?>

El resultado del ejemplo sería:

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

Ejemplo #3 Ejemplo de JsonSerializable::jsonSerialize() devolviento un 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);
?>

El resultado del ejemplo sería:

1

Ejemplo #4 Ejemplo de JsonSerializable::jsonSerialize() devolviendo un 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('¡Hola!'), JSON_PRETTY_PRINT);
?>

El resultado del ejemplo sería:

"¡Hola!"

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User Contributed Notes 4 notes

up
78
benkuhl at gmail dot com
11 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"}

?>
up
17
tomasz dot darmetko at gmail dot com
7 years ago
Nested json serializable objects will be serialized recursively. No need to call ->jsonSerialize() on your own. It is especially useful in collections.

<?php

class NestedSerializable implements \JsonSerializable
{

private
$serializable;

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

public function
jsonSerialize()
{
return [
'serialized' => $this->serializable
];
}

}

class
SerializableCollection implements \JsonSerializable {

private
$elements;

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

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

}

// Outputs: [{"serialized":null},{"serialized":null},{"serialized":{"serialized":null}}]
echo json_encode(
new
SerializableCollection([
new
NestedSerializable(null),
new
NestedSerializable(null),
new
NestedSerializable(new NestedSerializable(null))
])
);

?>
up
5
info at digistratum dot com
7 years ago
Here's a small test/proof that makes it easy to see some comparative results. Null was the one I was interested in since it was not documented:

<?php
class jsontest implements JsonSerializable {
function
__construct($value) { $this->value = $value; }
function
jsonSerialize() { return $this->value; }
}

print
"Null -> " . json_encode(new jsontest(null)) . "\n";
print
"Array -> " . json_encode(new jsontest(Array(1,2,3))) . "\n";
print
"Assoc. -> " . json_encode(new jsontest(Array('a'=>1,'b'=>3,'c'=>4))) . "\n";
print
"Int -> " . json_encode(new jsontest(5)) . "\n";
print
"String -> " . json_encode(new jsontest('Hello, World!')) . "\n";
print
"Object -> " . json_encode(new jsontest((object) Array('a'=>1,'b'=>3,'c'=>4))) . "\n";
?>

Output is:
Null -> null
Array -> [1,2,3]
Assoc. -> {"a":1,"b":3,"c":4}
Int -> 5
String -> "Hello, World!"
Object -> {"a":1,"b":3,"c":4}
up
1
david at vanlaatum dot id dot au
9 years 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
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