Laravel 更新时未调用观察者属性

Question

I am looking into observers and I found out that instead of calling an observer during the boot() method of the App\Providers\EventServiceProvider laravel can call it using the property protected $observers .

It works perfectly fine when calling it in the boot method, but it does not work when I put it in the property.

What am I doing wrong? I could not find any other explanation in the documentation.

My eventServiceProvider:

class EventServiceProvider extends ServiceProvider
{
    /**
     * Summary of Observers
     * @var mixed
     */
    protected $observers = [
        User::class => [UserObserver::class],
    ];

    /**
     * Register any events for your application.
     *
     * @return void
     */
    public function boot()
    {
        //User::observe(UserObserver::class);
        //Above line is commented because property $observers is used, but uncommented when property observers is commented.
    }

My observer:

class UserObserver
{

    /**
     * Handle the User "updated" event.
     *
     * @param  \App\Models\User  $user
     * @return void
     */
    public function updated(User $user)
    {
        $dirty = $user->getChanges();
        dump($user);
        dd($dirty);
    }
}

Answer 1

Have you tried calling $this->register(); inside the boot function?

class EventServiceProvider extends ServiceProvider
{
    /**
     * Summary of Observers
     * @var mixed
     */
    protected $observers = [
        User::class => [UserObserver::class],
    ];

    /**
     * Register any events for your application.
     *
     * @return void
     */
    public function boot()
    {
        $this->register();
    }