firebase - 从 Firebase 数据库读取数据并在小部件加载时显示详细信息

Question

在我的颤振项目中，我想从当前登录用户的 Firebase 数据库中读取数据并显示数据库中的用户名并显示在 appbar[Line 43:title: Text('$userName'),] 的Page.I 试过下面的代码，但它在第 26 行给出错误 [Line:final FirebaseUser user = _auth.currentUser();]。错误在于关键字“_auth.currentUser()”错误是：“Future”类型的值无法分配给“FirebaseUser”类型的变量

这是代码：

import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:udharibook/Screens/UserProfile.dart';
import 'package:udharibook/services/authservice.dart';
import 'Customer_Support.dart';
import 'package:udharibook/services/UserData.dart';

class DashboardPage extends StatefulWidget {
  @override
  _DashboardPageState createState() => _DashboardPageState();
}

class _DashboardPageState extends State<DashboardPage> {

  List<UserData> userdata = [];
  String userName;
  @override
  void initState()
  {
    super.initState();
    FirebaseAuth _auth = FirebaseAuth.instance;
    DatabaseReference DBRef = FirebaseDatabase.instance.reference().child('Users');
    final FirebaseUser user =  _auth.currentUser();
    DBRef.child(user.uid).once().then((DataSnapshot user)
    {
      userName = user.value['Name'];
      setState(() {
        print(userName);
      });
    });

  }



  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('$userName'),
        backgroundColor: Color.fromRGBO(162, 42, 43, 1.0),
        actions: <Widget>[
          IconButton(
              icon: Icon(Icons.search),
              onPressed: () {
                print("Search Clicked");
              }),
          IconButton(
              icon: Icon(Icons.sort),
              onPressed: () {
                print("Sort Clicked");
              }),
        ],
      ),
      drawer: Drawer(
        child: ListView(
          children: <Widget>[
            DrawerHeader(
              child: Text("mehul jain"),
              decoration: BoxDecoration(
                color: Color.fromRGBO(162, 42, 43, 1.0),
              ),
            ),
            CustomMenu(
                Icons.person,
                'Profile',() => {

                      Navigator.pop(context),
                      Navigator.push(
                          context,
                          new MaterialPageRoute(
                              builder: (context) => UserProfile()))
                    }),
            CustomMenu(Icons.assessment, 'Reports', () => {}),
            CustomMenu(Icons.settings, 'Settings', () => {}),
            CustomMenu(
                Icons.perm_phone_msg,
                'Customer Support',
                () => {
                      Navigator.pop(context),
                      Navigator.push(
                          context,
                          new MaterialPageRoute(
                              builder: (context) => CustSupport()))
                    }),
            CustomMenu(Icons.lock, 'Log Out', () => {AuthService().signOut()}),
          ],
        ),
      ),
    );
  }
}

class CustomMenu extends StatelessWidget {
  IconData icon;
  String text;
  Function onTap;

  CustomMenu(this.icon, this.text, this.onTap);

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Padding(
        padding: EdgeInsets.fromLTRB(8.0, 0.0, 8.0, 0.0),
        child: Container(
            decoration: BoxDecoration(
                border:
                    Border(bottom: BorderSide(color: Colors.grey.shade400))),
            child: InkWell(
                splashColor: Colors.redAccent,
                onTap: onTap,
                child: Container(
                  height: 60.0,
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: <Widget>[
                      Row(
                        children: <Widget>[
                          Icon(icon),
                          Padding(
                              padding: const EdgeInsets.all(8.0),
                              child: Text(
                                text,
                                style: TextStyle(
                                    fontSize: 17.0, fontFamily: 'Exo2'),
                              )),
                        ],
                      ),
                      Icon(Icons.arrow_right),
                    ],
                  ),
                ))));
  }
}

标签： firebaseflutterdartfirebase-realtime-database

Answer 1

currentUser()返回 a Future<FirebaseUser>，因此您必须执行以下操作：

    _auth.currentUser().then((curUser)
    {
      DBRef.child(curUser.uid).once().then((DataSnapshot user)
      {
        userName = user.value['Name'];
        setState(() {
         print(userName);
       });
      });
     });

https://dart.dev/codelabs/async-await