Question

在条件“（（snapshot.data ['role'] =='admin'）”）之后，页面应导航至adminPage。 home.dart

class  Home extends StatelessWidget {
      const Home({ Key key, this.user}) : super(key: key);
      final FirebaseUser user;

  @override
  Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(
            title: Text('Hi! ${user.email}'),
      ),
      body: StreamBuilder<DocumentSnapshot> (
        stream: Firestore.instance.collection('users').document(user.uid).snapshots(),
        builder: (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
          if (snapshot.hasError) {
            return Text('Error: ${snapshot.error}');
          }
          switch(snapshot.connectionState) {
            case ConnectionState.waiting:return Text('Loading...');
            default:
              if (snapshot.data['role'] == 'admin') {
                Navigator.pushReplacement(context, MaterialPageRoute(builder: (context) => AdminPage(user: user)));
              } else {
                Navigator.pushReplacement(context, MaterialPageRoute(builder: (context) => MemberPage(user: user)));
              } 
              }
          }; 
        },),
    );
  }

如您所见，我正在使用Navigator.pushReplacement进行导航。但是，我遇到了这样的错误。

I/flutter (30480): builds parent widgets before children, which means a dirty descendant will always be built.
I/flutter (30480): Otherwise, the framework might not visit this widget during this build phase.
I/flutter (30480): The widget on which setState() or markNeedsBuild() was called was:
I/flutter (30480):   Overlay-[LabeledGlobalKey<OverlayState>#a7637](state: OverlayState#fbfaa(tickers: tracking 4
I/flutter (30480):   tickers, entries: [OverlayEntry#1d0eb(opaque: true; maintainState: false),
I/flutter (30480):   OverlayEntry#bf6a0(opaque: false; maintainState: true), OverlayEntry#6ab73(opaque: false;
I/flutter (30480):   maintainState: false), OverlayEntry#be324(opaque: false; maintainState: true)]))
I/flutter (30480): The widget which was currently being built when the offending call was made was:
I/flutter (30480):   StreamBuilder<DocumentSnapshot>(dirty, state: _StreamBuilderBaseState<DocumentSnapshot,
I/flutter (30480):   AsyncSnapshot<DocumentSnapshot>>#2644b)
I/flutter (30480): 
I/flutter (30480): When the exception was thrown, this was the stack:
I/flutter (30480): #0      Element.markNeedsBuild.<anonymous closure> 
package:flutter/…/widgets/framework.dart:3497
I/flutter (30480): #1      Element.markNeedsBuild 
package:flutter/…/widgets/framework.dart:3523
I/flutter (30480): #2      State.setState 
package:flutter/…/widgets/framework.dart:1138
I/flutter (30480): #3      OverlayState.insertAll 
package:flutter/…/widgets/overlay.dart:301
I/flutter (30480): #4      OverlayRoute.install 
package:flutter/…/widgets/routes.dart:43
I/flutter (30480): #5      TransitionRoute.install 
package:flutter/…/widgets/routes.dart:184
I/flutter (30480): #6      ModalRoute.install 
package:flutter/…/widgets/routes.dart:899
I/flutter (30480): #7      NavigatorState.pushReplacement 
package:flutter/…/widgets/navigator.dart:1729
I/flutter (30480): #8      Navigator.pushReplacement 
package:flutter/…/widgets/navigator.dart:1055

这是我的adminPage。（请注意，我已经将其导入到我的LoginPage中）。

AdminMainPage.dart

import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';

class AdminPage extends StatefulWidget {
  @override
  const AdminPage({ Key key, this.user}) : super(key: key);
  final FirebaseUser user;
  _AdminPageState createState() => _AdminPageState();
}

class _AdminPageState extends State<AdminPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: new Text("Mobile Registration App"),
        backgroundColor: Colors.teal,
      ),
      body: new Column(
        crossAxisAlignment: CrossAxisAlignment.center,
      ),
    );
  }
}

我已经浪费了很多时间来解决此问题。这个问题在home.dart

经过验证的用户“ isAdmin”之后如何导航到adminPage，否则将变为memberPage

0 个答案: