UUIDs-In-Laravel-Part-2.php

/**
 * Binds creating/saving events to create UUIDs (and also prevent them from being overwritten).
 *
 * @return void
 */
public static function bootUuidModel()
{
    static::creating(function ($model) {
        // Don't let people provide their own UUIDs, we will generate a proper one.
        $model->uuid = Uuid::uuid4()->toString();
    });

    static::saving(function ($model) {
        // What's that, trying to change the UUID huh?  Nope, not gonna happen.
        $original_uuid = $model->getOriginal('uuid');

        if ($original_uuid !== $model->uuid) {
            $model->uuid = $original_uuid;
        }
    });
}

you are probably better of throwing an exception.

if ($original_uuid !== $model->uuid) {
            throw new IdentityIntegrityException()
}

So you will know when your code screws up, instead of never knowing.