model json cast adds a cache

[cxlblm]

We have a json usage scenario with the following code:

class User extends Model
{
    protected $fillable = [
        'extra',
    ];
    
    protected $casts = [
        'extra' => 'array',
    ];
}

$largeArray = range(0, 10000);

$user = (new User)->fill([
     'extra' => $largeArray
]);


for ($i = 0; $i <= 10000; ++$i) {
    $extra = $user->extra;
}

It takes 0.00051963460445404 seconds to get the properties each time on php 8.1, because it needs to call the json_decode function each time to parse the string into an array.

Now there are two ways to solve this problem：

1. introduce a local temporary variable
2. add a cache to the model to temporarily store the converted properties

The first solution is fine for shorter contexts where we can reuse temporary variables, but it is not a good solution if we need to use the json properties of the model in a different context. Personally, I think the second solution is a better solution, but it may also bring code complexity.

trait CachedAttribute
{
    private $cachedAttributes;

    protected function castAttribute($key, $value)
    {
        if ($this->isJsonCastable($key) && !isset($this->cachedAttributes, $key)) {
            $this->cachedAttributes[$key] = parent::castAttribute($key, $value);
        }
        return $this->cachedAttributes[$key];
    }

    protected function castAttributeAsJson($key, $value)
    {
        $this->cachedAttributes[$key] = $value;

        return parent::castAttributeAsJson($key, $value);
    }
}

I would like to hear if there is a better solution for everyone. My English is not very good, I need to use the translation software to communicate with everyone, if there is a description of inaccurate places hope you understand.