登錄按鈕 firebase

Question

我正在嘗試使用谷歌實現 firebase 中的登錄按鈕，但所有教程都是舊的。 我在以下位置遇到錯誤： onPressed: () => authService.googleSignIn()這是我用於身份驗證的代碼：

import 'package:firebase_auth/firebase_auth.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:rxdart/rxdart.dart';

class AuthService {
   // Dependencies
  final GoogleSignIn _googleSignIn = GoogleSignIn();
  final FirebaseAuth _auth = FirebaseAuth.instance;
  final Firestore _db = Firestore.instance;

  // Shared State for Widgets
  Observable<FirebaseUser> user; // firebase user
  Observable<Map<String, dynamic>> profile; // custom user data in Firestore
  PublishSubject loading = PublishSubject();

  // constructor
AuthService() {
    user = Observable(_auth.onAuthStateChanged);

    profile = user.switchMap((FirebaseUser u) {
      if (u != null) {
        return _db
            .collection('users')
            .document(u.uid)
            .snapshots()
            .map((snap) => snap.data);
      } else {
        return Observable.just({});
      }
    });
  }

  Future<String> _testSignInWithGoogle() async {
    final GoogleSignInAccount googleUser = await _googleSignIn.signIn();
    final GoogleSignInAuthentication googleAuth =
        await googleUser.authentication;
    final AuthCredential credential = GoogleAuthProvider.getCredential(
      accessToken: googleAuth.accessToken,
      idToken: googleAuth.idToken,
    );
    final FirebaseUser user =
          (await _auth.signInWithCredential(credential)).user;
    assert(user.email != null);
    assert(user.displayName != null);
    assert(!user.isAnonymous);
    assert(await user.getIdToken() != null);


    final FirebaseUser currentUser = await _auth.currentUser();
    assert(user.uid == currentUser.uid);


    return 'signInWithGoogle succeeded: $user';
  }

  Future<String> signOut() async {
    try {
      await _auth.signOut();
      return 'SignOut';
    } catch (e) {
      return e.toString();
    }
  }
}

// TODO refactor global to InheritedWidget
final AuthService authService = AuthService();

這是登錄頁面

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'auth.dart';
import 'package:google_sign_in/google_sign_in.dart';

class LoginScreen extends StatefulWidget {
  @override
  _LoginPageState createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Center(
            child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        LoginButton(), // <-- Built with StreamBuilder
        UserProfile()
      ],
    )));
  }
}

class UserProfile extends StatefulWidget {
  @override
  UserProfileState createState() => UserProfileState();
}

class UserProfileState extends State<UserProfile> {
  Map<String, dynamic> _profile;
  bool _loading = false;

  @override
  initState() {
    super.initState();

    // Subscriptions are created here
    authService.profile.listen((state) => setState(() => _profile = state));

    authService.loading.listen((state) => setState(() => _loading = state));
  }

  @override
  Widget build(BuildContext context) {
    return Column(children: <Widget>[
      Container(padding: EdgeInsets.all(20), child: Text(_profile.toString())),
      Text(_loading.toString())
    ]);
  }
}

class LoginButton extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StreamBuilder(
        stream: authService.user,
        builder: (context, snapshot) {
          if (snapshot.hasData) {
            return MaterialButton(
              onPressed: () => authService.signOut(),
              color: Colors.red,
              textColor: Colors.white,
              child: Text('Signout'),
            );
          } else {
            return MaterialButton(
              onPressed: () => authService.googleSignIn(),
              color: Colors.white,
              textColor: Colors.black,
              child: Text('Login with Google'),
            );
          }
        });
  }
}

Answer 1

我在異步方法中使用AuthService.googleSignIn()所以不能分配給同步方法

onPressed: () => authService.googleSignIn() 

像這樣使用

onPressed: () { authService.googleSignIn() }