flutter - 使用 dart 中的按钮更改 boolean 状态

Question

这是我的第一个堆栈溢出帖子，所以请在需要时给我一些 build 性的批评。
我正在开发一个应用程序，它需要有两种单独的帐户类型，一个学生帐户类型和一个辅导员帐户类型。我决定使用自定义声明代码来区分这两种帐户类型。我做了一个，以便用户帐户设置存在于firestore数据库中，并且我正在尝试这样做，以便当我单击注册屏幕中的一个按钮时，它将一个 boolean 值设置为true。我尝试在另一个身份验证类中调用 returnCounselor 函数，但收到此错误。 “方法‘returnCounselor’没有为‘Register’类型定义。”
进一步的背景知识在我设置了身份验证的类中，我调用了一个函数，该函数接受两个参数，即用户名和辅导员变量的状态，这就是我输入辅导员变量的地方。
我试图让按钮在身份验证类中设置辅导员变量的状态，但显然我可以设置可行的状态，除非它位于有状态的小部件中。这是我的代码

//database class

import 'package:cloud_firestore/cloud_firestore.dart';


class DatabaseService {

  final String uid;

  DatabaseService({this.uid});

  //collection reference
  final CollectionReference userCollection = Firestore.instance.collection('User Data');

  Future updateUserData(String name, bool counselor) async {
    return await userCollection.document(uid).setData({
      'name': name,
      'Counselor': true,

    });
  }
}

//register class stful widget
 import 'package:flutter/material.dart';
import 'package:strength_together/services/auth.dart';
import 'package:strength_together/shared/constants.dart';
import 'package:strength_together/shared/loading.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:strength_together/models/user.dart';
import 'package:strength_together/services/database.dart';
import 'package:strength_together/services/auth.dart';

class Register extends StatefulWidget {

  final Function toggleView;
  Register({this.toggleView });

  @override
  _RegisterState createState() => _RegisterState();
}

class _RegisterState extends State<Register> {

  final AuthService _auth = AuthService();
  final _formKey = GlobalKey<FormState>();
  bool loading = false;


  //text field state
  String email = '';
  String password = '';
  String error = '';

  //set counselor state
  //setCounselor(){
  //counselor = true;
  //}
  bool counselor = false;

  bool returnCounselor(){
    return counselor;
  }

  @override
  Widget build(BuildContext context) {


    return loading ? Loading() : Scaffold(
      backgroundColor: Colors.grey[900],
      appBar: AppBar(
        backgroundColor: Colors.black,
        elevation: 0.0,
        title: Text(
            'Sign up to Strength Together',
            style: TextStyle(
              fontWeight: FontWeight.bold,
              color: Colors.yellow,
            ),
        ),
        actions: <Widget>[
          FlatButton.icon(
            icon: Icon(
                Icons.person,
                color: Colors.yellow,
            ),
            label: Text(
              'Sign in',
              style: TextStyle(
                color: Colors.yellow,
              ),
            ),
            onPressed: () {
              widget.toggleView();
            }
          )
        ],
      ),
      body: Container(
        padding: EdgeInsets.symmetric(vertical: 20.0, horizontal: 50.0),
        child: Form(
          key: _formKey,
          child: Column(
            children: <Widget>[
              SizedBox(height: 20.0,),
              TextFormField(
                decoration: textInputDecoration.copyWith(hintText: 'Email'),
                validator: (val) => val.isEmpty ? 'Enter an email': null,
                onChanged: (val){
                  setState(() => email = val);
                },
              ),
              SizedBox(height: 20.0),
              TextFormField(
                decoration: textInputDecoration.copyWith(hintText: 'Password'),
                validator: (val) => val.length < 6 ? 'Enter a password 6+ chars long': null,
                obscureText: true,
                onChanged: (val){
                  setState(() => password = val);
                },
              ),
              SizedBox(height: 20.0),
              RaisedButton(
                color: Colors.black,
                child: Text(
                  'Register',
                  style: TextStyle(color: Colors.yellow),
                ),
                onPressed: () async{
                  if(_formKey.currentState.validate()){
                    setState(() => loading = true);
                    dynamic result = await _auth.registerWithEmailAndPassword(email, password);
                    if(result == null){
                      setState(() {
                        error = 'Please supply a valid email';
                        loading = false;
                      });
                    }
                  }
                }
              ),
              SizedBox(height:12.0),
              Text(
                error,
                style: TextStyle(color: Colors.red, fontSize: 14.0),
              ),
            ],
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () async{
          counselor = true;
          //setCounselor();
        },
      ),
    );
  }
}

//authentification class
import 'package:firebase_auth/firebase_auth.dart';
import 'package:strength_together/Screens/authenticate/register.dart';
import 'package:strength_together/models/user.dart';
import 'package:strength_together/services/database.dart';
import 'package:flutter/material.dart';



class AuthService{

  final FirebaseAuth _auth = FirebaseAuth.instance;

  //instance of couns
  bool counselor = Register().returnCounselor();

//bool counselor = false;

//setCounselor(){
  //counselor = true;
  //}


  //create user obj based on firebase user
  User _userFromFirebaseUser(FirebaseUser user){
    return user != null ? User(uid: user.uid) : null;
  }

  //auth change user stream
  Stream<User> get user {
    return _auth.onAuthStateChanged
    .map(_userFromFirebaseUser);
  }

  //method to sign in anon
  Future signInAnon() async{
    try{
      AuthResult result = await _auth.signInAnonymously();
      FirebaseUser user = result.user;
      return _userFromFirebaseUser(user);
    }catch(e){
      print(e.toString());
      return null;
    }
  }

  //method to sign in with email/pass
  Future signInWithEmailAndPassword(String email, String password) async{
    try{
      AuthResult result = await _auth.signInWithEmailAndPassword(email: email, password: password);
      FirebaseUser user = result.user;
      return _userFromFirebaseUser(user);
    }catch(e){
      print(e.toString());
      return null;
    }
  }

  //method to register with email/pass
  Future registerWithEmailAndPassword(String email, String password) async{
    try{
      AuthResult result = await _auth.createUserWithEmailAndPassword(email: email, password: password);
      FirebaseUser user = result.user;

      //create a new document for that user with the uid
      await DatabaseService(uid: user.uid).updateUserData('New user', counselor);

      return _userFromFirebaseUser(user);
    }catch(e){
      print(e.toString());
      return null;
    }
  }

  //sign in with google

  //sign out
  Future signOut() async{
    try{
      return await _auth.signOut();
    }catch(e){
      print(e.toString());
      return null;
    }
  }

Answer 1

我会将您的 getCounselor 方法放在您的 AuthService 类中，使顾问成为私有(private)的。像这样:

bool _counselor;

bool get counselor => _counselor;

void setCounselor(bool counselor) {
  _counselor = counselor;
}

然后，您可以在注册小部件中调用它。

_auth.couselor;

_auth.setCounselor;

处理此问题的最佳方法是使用 ChangeNotifier 类，然后使用 Provider 将其注入(inject)您的 Register 类。

class AuthBloc extends ChangeNotifier {
  bool _counselor;
  String _userName;
  String _email;
  String _password;

  bool get counselor => _counselor;
  String get userName => _userName;

  void setCounselor(bool counselor) {
    _counselor = counselor;
    notifyListeners();
  }

  void setUserName(String userName) {
    _userName = userName;
    notifyListeners();
  }

  void setEmail(String email) {
    _email = email;
    notifyListeners();
  }

  void setPassword(String password) {
    _password = password;
    notifyListeners();
  }

  AuthService _auth = AuthService();

  Future<User> signInAnon() async{
   return await _auth.signInAnon();
  }

  Future<User> signInWithEmailAndPassword() async{
    _return await _auth.signInWithEmailAndPassword(_email, _password);
  }

  Future<User> createUserWithEmailAndPassword() async{
    _return await _auth.createUserWithEmailAndPassword(_email, _password);
  }
}

然后你也可以把你的 AuthService 和 Database Service 方法放在那里。
在你的 main.dart 文件中:

ChangeNotifierProvider(
  create: (context) => AuthBloc(),
  child: MyApp(),
),

然后，在您的注册小部件中:

Consumer<AuthBloc>(
  builder: (context, bloc, child) {
  return TextFormField(
            decoration: textInputDecoration.copyWith(hintText: 'Password'),
            validator: (val) => val.length < 6 ? 'Enter a password 6+ chars long': 
            null,
            obscureText: true,
            onChanged: (val){
              bloc.setPassword(val);
            },
 },
);

只需在需要访问集团的任何地方使用消费者小部件。