英文:
Flutter - Unhandled Exception: Null check operator used on a null value
问题
抱歉，你要求只返回翻译好的部分，以下是代码部分的翻译：
我正在尝试使用GetX控制器从FirebaseFirestore文档初始化字段，但我遇到以下错误：
> 未处理的异常：在空值上使用了空检查运算符。
控制器已创建，但由于在空值上使用了空检查运算符，因此未初始化。以下是我的代码：
class DataController extends GetxController{
DocumentSnapshot? userDocument;
FirebaseAuth auth = FirebaseAuth.instance;
getUserProfileData() {
FirebaseFirestore.instance
.collection('users')
.doc(auth.currentUser!.uid) //在空值上使用了空检查运算符
.snapshots()
.listen((event) {
userDocument = event;
});
}
@override
void onInit() {
super.onInit();
getUserProfileData();
}
}
我的错误日志：
E/flutter (11591): #1 DataController.onInit
data_controller.dart:76
E/flutter (11591): #2 GetLifeCycleBase._onStart
lifecycle.dart:66
E/flutter (11591): #3 InternalFinalCallback.call
lifecycle.dart:12
E/flutter (11591): #4 GetInstance._startController
get_instance.dart:253
E/flutter (11591): #5 GetInstance._initDependencies
get_instance.dart:204
E/flutter (11591): #6 GetInstance.find
get_instance.dart:301
E/flutter (11591): #7 GetInstance.put
get_instance.dart:86
E/flutter (11591): #8 Inst.put
extension_instance.dart:89
E/flutter (11591): #9 main
main.dart:23
E/flutter (11591): <asynchronous suspension>
E/flutter (11591):
如果你需要更多的帮助，请随时告诉我。
英文:
I am trying to initialize fields from a FirebaseFirestore document using GetXcontroller but I am getting the following error:
> Unhandled Exception: Null check operator used on a null value.
The Controller gets created but it doesn't get initialized because of
the null check operator used on null value. Here's my code:
class DataController extends GetxController{
DocumentSnapshot? userDocument;
FirebaseAuth auth = FirebaseAuth.instance;
getUserProfileData() {
FirebaseFirestore.instance
.collection('users')
.doc(auth.currentUser!.uid) //Null check operator used on a null value
.snapshots()
.listen((event) {
userDocument = event;
});
}
@override
void onInit() {
super.onInit();
getUserProfileData();
}
}
My error log:
E/flutter (11591): #1 DataController.onInit
data_controller.dart:76
E/flutter (11591): #2 GetLifeCycleBase._onStart
lifecycle.dart:66
E/flutter (11591): #3 InternalFinalCallback.call
lifecycle.dart:12
E/flutter (11591): #4 GetInstance._startController
get_instance.dart:253
E/flutter (11591): #5 GetInstance._initDependencies
get_instance.dart:204
E/flutter (11591): #6 GetInstance.find
get_instance.dart:301
E/flutter (11591): #7 GetInstance.put
get_instance.dart:86
E/flutter (11591): #8 Inst.put
extension_instance.dart:89
E/flutter (11591): #9 main
main.dart:23
E/flutter (11591): <asynchronous suspension>
E/flutter (11591):
答案1
得分: 1
错误提示您，在此表达式中：
auth.currentUser!.uid
currentUser 的值为 null。这意味着用户在此时尚未通过身份验证。请确保在执行代码的这一点之前进行用户登录。作为防护措施，您还应手动检查用户在调用此链之前是否已经通过身份验证。例如，可以这样做：
FirebaseFirestore.instance
.collection('users')
.doc(auth.currentUser!.uid) //现在可以在这里使用强制解包
// ...
}```
<details>
<summary>英文:</summary>
The error tells you that in this expression
auth.currentUser!.uid
the value of `currentUser` is null. This means that the user is not authenticated at that point. Make sure to perform user login before reaching this point of your code. As a safeguard you should also manually check if the user is authenticated before calling this chain. For example via
if (auth.currentUser != null) {
FirebaseFirestore.instance
.collection('users')
.doc(auth.currentUser!.uid) //Force unwrapping is now fine here
// ...
}
</details>
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论