小编Bha*_*510的帖子

所以我的代码的问题是，一旦我按下提交按钮，我的屏幕就会变黑，然后我无法保存下一个响应。我希望一旦提交我的表单就应该重置以供重复使用，并且应该准备好接受用户的下一个响应，是的，黑屏也应该消失。

import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MaterialApp(home: MyApp()));
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  TextEditingController problemBox = TextEditingController();

  final db = FirebaseFirestore.instance;

  List _listItem = ["Category 1", "Category 2", "Category 3", "Category 4"];
  List _listItem1 = [
    "Sub Category 1",
    "Sub Category 2",
    "Sub Category 3",
    "Sub Category 4"
  ];
  List _listItem2 = ["CRIS", "ADMINISTRATION", "ZONE", "DEPARTMENT"];

  String dropdownValue; …

Dart 分析显示以下错误：

错误：未定义类“FirebaseUser”。（[quizmaker] lib\services\auth.dart:7 处的 undefined_class）

错误：名称“User”在库“package:firebase_auth/firebase_auth.dart”和“package:quizmaker/models/user.dart”中定义。（ambigious_import 位于 [quizmaker] lib\services\auth.dart:7）

错误：名称“User”在库“package:firebase_auth/firebase_auth.dart”和“package:quizmaker/models/user.dart”中定义。（ambigious_import 位于 [quizmaker] lib\services\auth.dart:8）

错误：“用户”不是函数。（非函数调用位于 [quizmaker] lib\services\auth.dart:8）

错误：名称“User”在库“package:firebase_auth/firebase_auth.dart”和“package:quizmaker/models/user.dart”中定义。（ambigious_import 位于 [quizmaker] lib\services\auth.dart:15）

代码如下：

import 'package:firebase_auth/firebase_auth.dart';
import 'package:quizmaker/models/user.dart';

class AuthService {
  FirebaseAuth _auth = FirebaseAuth.instance;

  User _userFromFirebaseUser(FirebaseUser user){
    return user != null ? User(uid: user.uid) : null;
  }

  Future signInEmailAndPassword(String email, password) async {
    try {
      UserCredential authResult = await _auth.signInWithEmailAndPassword(
          email: email, password: password);
      User? firebaseUser = authResult.user;
      return _userFromFirebaseUser(firebaseUser);
    } catch (e) {
      print(e.toString());
    }
  }
}