_TypeError(类型 'Future<dynamic>' 不是类型"小部件"的子类型)

Question

am试图从数据中调用用户(am使用firebase作为数据库(个人资料页面不起作用，无法了解更多信息，请查看我昨天发布的另一个问题：FirebaseException([cloud_firestore/univailable]服务当前不可用，以及如何解决

import 'package:cached_network_image/cached_network_image.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:yumor/models/progress.dart';
import 'package:yumor/models/user_model.dart';
class profile extends StatefulWidget {
const profile({Key? key,required this.userProfile}) : super(key: key);
final String? userProfile;


@override
State<profile> createState() => _profileState();
}
class _profileState extends State<profile> {
final userRef = FirebaseFirestore.instance.collection('users');
buildprofileheader() async{
final doc=await userRef.doc(widget.userProfile).get();
if(doc.exists){ 
var data=doc.data();
}
return FutureBuilder(future:FirebaseFirestore.instance.collection('users').doc(userRef.id).get(),
builder: ((context, snapshot) {
if(!snapshot.hasData){
return CircularProgress();
}
UserModel user=UserModel.fromMap(Map);
return Padding(padding:EdgeInsets.all(16.0),
child: Column(
children: [
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Icon(Icons.account_circle, size: 90,)
],
),
Container(
alignment: Alignment.center,
padding: EdgeInsets.all(12.0),
child: Text(
user.Username as String,
style: TextStyle(
fontWeight: FontWeight.bold,
fontSize:16.0,
),
),
),
],
),
);
}),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
centerTitle: true,
title: Text(
"Profile",
),
),
body: ListView(children: <Widget>[
buildprofileheader(), // the error shows in this line <=======
]));
}
}

Answer 1

您的buildprofileheader返回类型是Future<Widget>，但它应该是Widget才能在ListView中使用，因此您需要使用其他FutureBuilder才能获得userRef。所以，用另一个来包装你当前的FutureBuilder。

Answer 2

至于逻辑部分，您可以简化未来方法的逻辑，比如

Future<UserModel?> getData() async {
try{
final userRef = FirebaseFirestore.instance.collection('users');
final doc = await userRef.doc(widget.userProfile).get();
if (doc.exists) {
var data = doc.data(); // not sure about this use case
} else {
return null;
}
final data = await FirebaseFirestore.instance
.collection('users')
.doc(userRef.id)
.get();
if (data.exists) {
UserModel user = UserModel.fromMap(data);
return user;
}
} catch(e){ }

}

为未来的方法创建一个状态变量，并像一样使用

late final future = getData(); 
Widget buildprofileheader() {
return FutureBuilder<UserModel?>(
future: future,
builder: ((context, snapshot) {
if (!snapshot.hasData) {
return CircularProgress();
}
return Padding(....

class _profileState extends State<profile> {
Future<UserModel?> getData() async {
final userRef = FirebaseFirestore.instance.collection('users');
final doc = await userRef.doc(widget.userProfile).get();
if (doc.exists) {
var data = doc.data(); // not sure about this use case
} else {
return null;
}
final data = await FirebaseFirestore.instance
.collection('users')
.doc(userRef.id)
.get();
if (data.exists) {
UserModel user = UserModel.fromMap(data);
return user;
}
}
late final future = getData();
Widget buildprofileheader() {
return FutureBuilder<UserModel?>(
future: future,
builder: ((context, snapshot) {
if (!snapshot.hasData) {
return CircularProgressIndicator();
}
return Padding(
padding: EdgeInsets.all(16.0),
child: Column(
children: [
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Icon(
Icons.account_circle,
size: 90,
)
],
),
Container(
alignment: Alignment.center,
padding: EdgeInsets.all(12.0),
child: Text(
user.Username as String,
style: TextStyle(
fontWeight: FontWeight.bold,
fontSize: 16.0,
),
),
),
],
),
);
}),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
centerTitle: true,
title: Text(
"Profile",
),
),
body: ListView(children: <Widget>[
buildprofileheader(),
]));
}
}