Implementing Custom Attribute Casting in Laravel Eloquent

<?php

namespace App\Casts;

use Illuminate\Contracts\Database\Eloquent\CastsAttributes;

// Example Value Object
class Money
{
    public function __construct(public int $amount, public string $currency = 'USD') {}

    public function __toString(): string
    {
        return $this->currency . ' ' . number_format($this->amount / 100, 2);
    }

    public function toArray(): array
    {
        return ['amount' => $this->amount, 'currency' => $this->currency];
    }
}

class MoneyCast implements CastsAttributes
{
    /**
     * Cast the given value.
     *
     * @param  \Illuminate\Database\Eloquent\Model  $model
     * @param  string  $key
     * @param  mixed  $value
     * @param  array  $attributes
     * @return \App\Casts\Money|null
     */
    public function get($model, string $key, $value, array $attributes): ?Money
    {
        if (is_null($value)) {
            return null;
        }
        $data = json_decode($value, true);
        return new Money($data['amount'], $data['currency'] ?? 'USD');
    }

    /**
     * Prepare the given value for storage.
     *
     * @param  \Illuminate\Database\Eloquent\Model  $model
     * @param  string  $key
     * @param  \App\Casts\Money|null  $value
     * @param  array  $attributes
     * @return string|null
     */
    public function set($model, string $key, $value, array $attributes): ?string
    {
        if (is_null($value)) {
            return null;
        }
        return json_encode($value->toArray());
    }
}

// In your Product model
namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use App\Casts\MoneyCast;

class Product extends Model
{
    /**
     * The attributes that should be cast.
     *
     * @var array
     */
    protected $casts = [
        'price' => MoneyCast::class,
    ];
}

// Usage:
// $product = Product::find(1);
// echo $product->price; // Accesses the Money object
// $product->price = new \App\Casts\Money(12999, 'EUR');
// $product->save();