对话框未显示

Question

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:authentication_signup/components/my_button.dart';
import 'package:authentication_signup/components/my_textfield.dart';
import 'package:authentication_signup/components/square_tile.dart';

class LoginPage extends StatefulWidget {
  const LoginPage({super.key});

  @override
  State<LoginPage> createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  //text editing controllers
  final usernameController = TextEditingController();
  final passwordController = TextEditingController();

  //sign user in method
  void signUserIn() async {
    //loading circle
    showDialog(context: context, builder: (context) {
      return const Center(
        child: CircularProgressIndicator(),
      );
    },);

    try {
      // Try signing in
      await FirebaseAuth.instance.signInWithEmailAndPassword(
        email: usernameController.text,
        password: passwordController.text,
      );

      // Close the loading dialog only if the widget is still mounted
      if (mounted) {
        Navigator.pop(context);
      }

    } on FirebaseAuthException catch (e) {
      // Close the loading dialog only if the widget is still mounted
      if (mounted) {
        Navigator.pop(context);
      }

      // Handle error
      if (e.code == 'user-not-found') {
        // Show error to user
        wrongEmailMessage();
      } else if (e.code == 'wrong-password') {
        // Show error to user
        wrongPasswordMessage();
      }
    } catch (e) {
      // Handle any other exceptions and close the loading dialog if mounted
      if (mounted) {
        Navigator.pop(context);
      }
      print('Error: $e');
    }
  }

  // Wrong email message pop-up
  void wrongEmailMessage() {
    if (mounted) {
      showDialog(
        context: context,
        builder: (context) {
          return const AlertDialog(
            title: Text('Incorrect email'),
            content: Text('No user found with that email.'),
          );
        },
      );
    }
  }

  // Wrong password message pop-up
  void wrongPasswordMessage() {
    if (mounted) {
      showDialog(
        context: context,
        builder: (context) {
          return const AlertDialog(
            title: Text('Incorrect password'),
            content: Text('The password you entered is incorrect.'),
          );
        },
      );
    }
  }

确保小部件已安装：如果在异步操作期间已卸载小部件，则尝试显示对话框将失败。在调用

Navigator.pop(context)

或显示对话框之前，请务必检查小部件是否仍已安装。

异步间隙：异步操作（例如使用 Firebase 登录）可能会导致 BuildContext 出现问题。使用 Mounted 属性检查小部件是否仍在树中。

Flutter Build Context：确保在调用 Navigator 或 showDialog 时使用正确的 BuildContext。

我尝试了这些并更新了代码，但当我输入错误的电子邮件或密码时，对话框仍然没有显示。它只是不登录并停留在登录页面本身，没有为用户弹出对话框

Answer 1

我认为你的代码应该可以正常工作，但你错过了逻辑处理！

如果在

auth

阶段发生任何异常您已经弹出了加载对话框。

因此，在调用这些方法

wrongPasswordMessage()

和

wrongEmailMessage()

时，由于这种情况，将不会显示错误对话框：

void wrongPasswordMessage() {
    if (mounted) {
      showDialog(
        context: context,
        builder: (context) {
          return const AlertDialog(
            title: Text('Incorrect password'),
            content: Text('The password you entered is incorrect.'),
          );
        },
      );
    }
  }

如果屏幕为

mounted

但未安装，因为您已弹出加载对话框，您将显示该对话框。

所以，我认为删除两种错误方法中的

if condition

将会出现错误对话框，或者您可以将该条件更改为：

if(!mounted){
 // show that dialog
}