Flutter：有没有更好的方法来处理 if/else 语句中每个条件的调用 setState()？答案

【问题标题】：Flutter: Is there a better way to handle calling setState() for each condition in an if/else statement?Flutter：有没有更好的方法来处理 if/else 语句中每个条件的调用 setState()？
【发布时间】：2023-03-27 22:38:01
【问题描述】：

我有我认为未优化的代码。基本上，如果发生 FirebaseAuthException，我想更改 errorString 的值。我是否使用 ChangeNotifier 代替？

Future<void> _signInWithEmailAndPassword(BuildContext context,AsyncSnapshot<String> userSnapshot,AsyncSnapshot<String> passwordSnapshot) async {
    try {
      final auth = Provider.of<AuthService>(context, listen: false);
      await auth.signInWithEmailAndPassword(
          userSnapshot.data.trim(), passwordSnapshot.data.trim());
          setState(() => errorString = 'Success');
    } on FirebaseAuthException catch (e) {
      // I don't want to call setState() in each condition
      if (e.code == 'invalid-credential') {
        setState(() {
          errorString = "Email address appears to be malformed/expired";
        });
      } else if (e.code == 'wrong-password') {
        setState(() {
          errorString = "Password associated with this email is wrong";
        });
      } else if (e.code == 'user-not-found') {
        setState(() {
          errorString = "Email has not been registered, please sign up :)";
        });
      } else if (e.code == 'user-disabled') {
        setState(() {
          errorString = "User with this email has been disabled :(";
        });
      } else if (e.code == 'too-many-requests') {
        setState(() {
          errorString = "Too many requests, please try again later.";
        });
      } else if (e.code == 'operation-not-allowed') {
        setState(() {
          errorString = "Signing in with email and password is not enabled";
        });
      } else if (e.code == 'account-exists-with-different-credential') {
        setState(() {
          errorString =
              "Email has already been registered. Reset your password.";
        });
      }
    } 
  }

【问题讨论】：

标签： flutter setstate state-management flutter-change-notifier

【解决方案1】：

我会做这样的事情：

const errMap = {
    'invalid-credential': "Email address appears to be malformed/expired",
    'wrong-password': "Password associated with this email is wrong",
    'user-not-found': "Email has not been registered, please sign up :)",
    'user-disabled': "User with this email has been disabled :(",
    'too-many-requests': "Too many requests, please try again later.",
    'operation-not-allowed': "Signing in with email and password is not enabled",
    'account-exists-with-different-credential': "Email has already been registered. Reset your password."
};

setState(() {
    errorString = errMap[e.code];
});

【讨论】：

【解决方案2】：

只需将setState 放在所有赞的末尾

 Future<void> _signInWithEmailAndPassword(BuildContext context,AsyncSnapshot<String> userSnapshot,AsyncSnapshot<String> passwordSnapshot) async {
    try {
      final auth = Provider.of<AuthService>(context, listen: false);
      await auth.signInWithEmailAndPassword(
          userSnapshot.data.trim(), passwordSnapshot.data.trim());
      setState(() => errorString = 'Success');
    } on FirebaseAuthException catch (e) {
      // I don't want to call setState() in each condition
      if (e.code == 'invalid-credential') {
       
          errorString = "Email address appears to be malformed/expired";
       
      } else if (e.code == 'wrong-password') {
      
          errorString = "Password associated with this email is wrong";
        
      } else if (e.code == 'user-not-found') {
        
          errorString = "Email has not been registered, please sign up :)";
       
      } else if (e.code == 'user-disabled') {
        
          errorString = "User with this email has been disabled :(";
        
      } else if (e.code == 'too-many-requests') {
         
          errorString = "Too many requests, please try again later.";
       
      } else if (e.code == 'operation-not-allowed') {
        
          errorString = "Signing in with email and password is not enabled";
        
      } else if (e.code == 'account-exists-with-different-credential') {
     
          errorString =
          "Email has already been registered. Reset your password.";
        
      }
      setState(() {})
    }
  }

【讨论】：