json_encode PHP objects with their protected properties

Question

Is there any way I can set up PHP objects so that when I try to convert them to JSON, all of their protected properties will be shown?

I have read other answers suggesting I add a toJson() function to the object, but that may not really help me a great lot. In most cases, I have an array of objects and I perform the encode on the array itself.

$array = [
    $object1, $object2, $object3, 5, 'string', $object4
];

return json_encode($array);

Yes, I can loop through this array and call toJson() on every element that has such method, but that just doesn't seem right. Is there a way I can use magic methods to achieve this?

Answer 1

You can implement the JsonSerializable interface in your classes so you have full control over how it is going to be serialized. You could also create a Trait to prevent copy pasting the serializing method:

<?php

trait JsonSerializer {
    public function jsonSerialize()
    {
        return get_object_vars($this);
    }
}

class Foo implements \JsonSerializable 
{
    protected $foo = 'bar';

    use JsonSerializer;
}

class Bar implements \JsonSerializable 
{
    protected $bar = 'baz';

    use JsonSerializer;   
}

$foo = new Foo;
$bar = new Bar;

var_dump(json_encode([$foo, $bar]));

Alternatively you could use reflection to do what you want:

<?php

class Foo
{
    protected $foo = 'bar';
}

class Bar
{
    protected $bar = 'baz';
}

$foo = new Foo;
$bar = new Bar;

class Seriailzer
{
    public function serialize($toJson)
    {
        $data = [];

        foreach ($toJson as $item) {
            $data[] = $this->serializeItem($item);
        }

        return json_encode($data);
    }

    private function serializeItem($item)
    {
        if (!is_object($item)) {
            return $item;
        }

        return $this->getProperties($item);
    }

    private function getProperties($obj)
    {
        $rc = new ReflectionClass($obj);

        return $rc->getProperties();
    }
}

$serializer = new Seriailzer();

var_dump($serializer->serialize([$foo, $bar]));