Laravel: ID as ValueObject is null after save - laravel

Question

I'm using ValueObject casting as an ID of my model. Everything works fine when I get a record from database, however when it coming to saving, the ID is null. If I comment "casts" out, ID is correct.
Example:
$game = new Game($data);
$game->created_by = $userId; // Id ValueObject
$game->save();
dd($game);
// attributes:
// "id" => null,
// "created_by" => Id{#value: 10},
Id ValueObject:
class Id
{
public function get($model, $key, $value, $attributes)
{
$this->value = $value;
return $this;
}
public function set($model, $key, $value, $attributes)
{
$this->value = $value;
}
public function value(): int
{
return $this->value;
}
public function __toString()
{
return (string) $this->value;
}
}
Model:
class Game extends Model
{
protected $casts = [
'id' => Id::class
];
}
What can I do with it?
Thanks in advance

Answer 1

Okey, I think that there should be a ValueObject and a CastingObject, I ended up with something similar to this:
class Game extends Model
{
protected $casts = [
'id' => IdCast::class
];
}
class IdCast implements CastsAttributes
{
public function get($model, $key, $value, $attributes)
{
return new Id(
$attributes['id']
);
}
public function set($model, $key, $value, $attributes)
{
return [
'id' => $value
];
}
}
class Id
{
private $value;
public function __construct($id)
{
$this->value = $id;
}
public function value(): int
{
return $this->value;
}
public function __toString()
{
return (string) $this->value;
}
}