我有一個Conversation可以設置為私人的。設置為 private 意味著user_idonconversations將被分配一個非空值。如果他有足夠的積分，用戶可以將對話設置為私人。前端擁有驗證邏輯，但我也想在后端進行。我已將事件設置為在模型保存時觸發：protected $dispatchesEvents = [    'saving' => ConversationSaving::class,];那個事件沒什么特別的：public function __construct(Conversation $conversation){    Log::info("[Event] " . get_class());    $this->conversation = $conversation;}事件服務提供者的邏輯是這樣的：ConversationSaving::class      => [    PreventMakingPrivate::class],ConversationMadePrivate::class => [    DeductCreditsForMakingPrivate::class],這個想法是觸發更新，如果更新失敗，ConversationMadePrivate事件永遠不會觸發?？刂破骺雌饋硐襁@樣：$conversation->update(['user_id' => Auth::user()->id]);Log::info('After update');Log::info($conversation->user_id);Log::info($conversation->user_id ? 't':'f');if(!$conversation->user_id){    return response([        'error' => 'Error making private',    ]);}event(new ConversationMadePrivate($conversation));return response([    'conversation' => $conversation->load('messages'),]);現在我在日志中得到的是：[2020-05-16 07:34:41] local.INFO: [Event] App\Events\ConversationSaving [2020-05-16 07:34:41] local.INFO: [Listener] App\Listeners\PreventMakingPrivate  [2020-05-16 07:34:41] local.INFO: [Listener] Not enough credits  [2020-05-16 07:34:41] local.INFO: After update  [2020-05-16 07:34:41] local.INFO: 1  [2020-05-16 07:34:41] local.INFO: t  [2020-05-16 07:34:41] local.INFO: [Event] App\Events\ConversationMadePrivate  [2020-05-16 07:34:41] local.INFO: [Listener] App\Listeners\DeductCreditsForMakingPrivate  所以代碼正確地進入監聽器并false從返回PreventMakingPrivate，但是模型仍然更新。我也試過設置 onConversation updating而不是saving，但同樣的事情發生了。我怎樣才能阻止更新？