为什么字符串在firebase中返回null

Question

//Anom loggin
    auth.SignInAnonymouslyAsync().ContinueWith(task =>
    {
        if (task.IsCanceled)
        {
            Debug.LogError("SignInAnonymouslyAsync was canceled.");
            return;
        }
        if (task.IsFaulted)
        {
            Debug.LogError("SignInAnonymouslyAsync encountered an error: " + task.Exception);
            return;
        }

        Firebase.Auth.FirebaseUser newUser = task.Result;
        Debug.LogFormat("User signed in successfully: {0} ({1})", newUser.DisplayName, newUser.UserId);

        userdataString = newUser.UserId;
        Debug.Log("userdatastring: " + userdataString);
    });

    Debug.Log("userdatastring out: " + userdataString);
}

当它离开匿名函数时，值返回null，但在其中，如果它返回我需要获取的id，知道如何获取字符串值吗？

Answer 1

firebase 函数是一个异步函数，这意味着在异步函数完成（成功或不成功状态）之前，不会运行内部回调

这意味着您的调试日志实际上是在异步函数的回调运行之前运行的。

以下是您可以执行的一些选项：

1. 让 firebase 异步函数在准备就绪时调用回调函数。

   public void DoAnonymousSignIn(){
       auth.SignInAnonymouslyAsync().ContinueWith(OnSignInDone);
   }
   
   private void OnSignInDone(Task<Firebase.Auth.FirebaseUser> task){
       if (task.IsCanceled){
           Debug.LogError("SignInAnonymouslyAsync was canceled.");
           return;
       }
   
       if (task.IsFaulted){
           Debug.LogError("SignInAnonymouslyAsync encountered an error: " + task.Exception);
           return;
       }
   
       Firebase.Auth.FirebaseUser newUser = task.Result;
       Debug.LogFormat("User signed in successfully: {0} ({1})", newUser.DisplayName, newUser.UserId);
   
       userdataString = newUser.UserId;
       Debug.Log("userdatastring: " + userdataString);
   }
   

2. 保持现在的方式，内联处理回调而不是使用回调函数，并设置一个变量将其标记为准备好或直接从中调用“SignInDone”函数（例如 SignInSuccess()和 SignInFailed())

3. 您还可以设置自己的回调事件并从其他脚本订阅它们：

   using System;
   
   public static Action OnSignInSuccess;
   

   然后在你的 firebase 异步回调中你可以这样做：

       // ... within auth.SignInAnonymouslyAsync() callback
   
       Firebase.Auth.FirebaseUser newUser = task.Result;
       Debug.LogFormat("User signed in successfully: {0} ({1})", newUser.DisplayName, newUser.UserId);
   
       userdataString = newUser.UserId;
   
       if(OnSignInSuccess != null)
           OnSignInSuccess.Invoke();
   }
   

   然后其他脚本可以订阅和取消订阅这个回调事件：

   void OnEnable(){
       YourScript.OnSignInSuccess += SignInSuccess;
   }
   
   void OnDisable(){
       YourScript.OnSignInSuccess -= SignInSuccess;
   }
   
   private void SignInSuccess(){
       Debug.Log("userdatastring: " + YourScript.staticInstance.userDataString);
   }