json_encode empty with no error [duplicate] - php

Question

This question already has answers here:
PHP class instance to JSON
(5 answers)
Closed 4 years ago.
I got an object. I need to turn into JSON for storage but when I try to encode it into JSON it returns an empty JSON object. When I tried to use json_last_error.
The code I used
echo $payload["sub"];
echo json_encode($user);
echo json_last_error_msg();
The result I get
"102573480781696194937{}No error".
The User class I'm trying to encode
<?php
/**
* Created by PhpStorm.
* User: Student
* Date: 13-4-2018
* Time: 10:40
*/
namespace php;
class User
{
private $isAdmin = false;
private $registeredFood = array();
private $googleID;
private $name;
private $notes = array();
private $email;
/**
* User constructor.
* #param $googleID
*/
public function __construct($googleID)
{
$this->googleID = $googleID;
}
/**
* #return mixed
*/
public function getGoogleID()
{
return $this->googleID;
}
/**
* #return bool
*/
public function isAdmin()
{
return $this->isAdmin;
}
/**
* #param bool $isAdmin
*/
public function setIsAdmin($isAdmin)
{
$this->isAdmin = $isAdmin;
}
/**
* #return array
*/
public function getRegisteredFood()
{
return $this->registeredFood;
}
/**
* #param array $registeredFood
*/
public function setRegisteredFood($registeredFood)
{
$this->registeredFood = $registeredFood;
}
/**
* #return mixed
*/
public function getName()
{
return $this->name;
}
/**
* #param mixed $name
*/
public function setName($name)
{
$this->name = $name;
}
/**
* #return array
*/
public function getNotes()
{
return $this->notes;
}
/**
* #param array $notes
*/
public function setNotes($notes)
{
$this->notes = $notes;
}
/**
* #return mixed
*/
public function getEmail()
{
return $this->email;
}
/**
* #param mixed $email
*/
public function setEmail($email)
{
$this->email = $email;
}
}
?>
I hope someone can help me

Answer 1

It is because your class's properties are private.
An example class with only private properties ...
php > class Foo { private $bar = 42; }
php > $obj = new Foo();
do not expose values:
php > echo json_encode($obj);
{}
But an example class with public properties ...
php > class Bar { public $foo = 42; }
php > $objBar = new Bar();
do it!
php > echo json_encode($objBar);
{"foo":42}
\JsonSerializable
PHP provide an'interafce \JsonSerializable that require a method jsonSerialize. This method is automatically called by json_encode().
class JsonClass implements JsonSerialize {
private $bar;
public function __construct($bar) {
$this->bar = $bar;
}
public function jsonSerialize() {
return [
'foo' => $this->bar,
];
}
}
I prefer this solution because is not good to expose publicly properties
serialization and unserialization ...
If you need to serialize and unserialize php object you can ...
php > class Classe { public $pub = "bar"; }
php > $obj = new Classe();
php > $serialized = serialize($obj);
php > $original = unserialize($serialized);
php > var_dump($original);
php shell code:1:
class Classe#2 (1) {
public $pub =>
string(3) "bar"
}
$serialized variable contains O:6:"Classe":1:{s:3:"pub";s:3:"bar";}. As you can see is not a json, but is a format that allow you to recreate original object using unserialize function.

Answer 2

You have a couple of options here.
Option 1: Make your class properties public
Like what sensorario mentioned, change the visibility of your properties so that it is accessible from outside the class, which is where you are calling json_encode.
Option 2: Introduce a method/function within the class to return the encoded JSON object
Have a toJson() function inside your User class.
Of course, there are way more options - such as extending User so that User is not "contaminated", etc.
But yup, the general problem is your private properties.