我正在 Flutter 中使用 Firestore 和 ListView。
对于列表中的某些项目,每个项目都可以正常工作,但是当我向下滚动超出所见限制时,我收到许多消息:“该方法在 null 上被调用”。
似乎 ListView.builder 没有正确处理来自 Firebase 或类似内容的所有日期请求。
这是代码:
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:father_home_flutter/screen_audio_selected.dart';
import 'package:father_home_flutter/model/utils.dart';
class AudioScreenList extends StatelessWidget {
static const String _collectionRussian = 'speech-ru';
static const String _loadingTextRussian = 'Loading...';
static const String _speechTitle = 'speechTitle';
static const String _speechSubtitle = 'speechSubtitle';
static const String _audioLink = 'audioLink';
static const String _pastorCode = 'pastorCode';
static const String _pastorName = 'pastorName';
static const String _id = "id";
@override
Widget build(BuildContext context) {
return Scaffold(
body: StreamBuilder(
stream: Firestore.instance
.collection(_collectionRussian)
.limit(100)
.orderBy(_id, descending: true)
.snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData)
return const Center(
child: Text(
_loadingTextRussian,
style: TextStyle(fontSize: 25.0, color: Colors.grey),
));
return ListView.builder(
itemCount: snapshot.data.documents.length,
itemBuilder: (BuildContext context, int i) =>
_buildRow(context, snapshot.data.documents[i]),
);
}));
}
Widget _buildRow(BuildContext context, DocumentSnapshot document) {
return Container(
margin: const EdgeInsets.fromLTRB(0.0, 8.0, 0.0, 0.0),
height: 90.0,
child: ListTile(
leading: Padding(
padding: EdgeInsets.fromLTRB(0.0, 20.0, 0.0, 0.0),
child: Hero(
tag: document[_audioLink],
child: new ClipOval(
child: Container(
width: 70.0,
height: 70.0,
child: Image.asset(
Utils.getImagePastor(document[_pastorCode]),
fit: BoxFit.cover,
),
)))),
title: Text(document[_speechTitle]),
subtitle:
Text(document[_speechSubtitle] + " - " + document[_pastorName]),
onTap: () => onPressed(context, document[_speechTitle],
document[_pastorCode], document[_audioLink])));
}
onPressed(BuildContext context, String speechTitle, String pastorCode,
String audioLink) {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
ScreenAudioSelected(speechTitle, pastorCode, audioLink)));
}
}
这是模拟器上的问题:
我在网上寻找如何处理它的方法,但我只是找到了模拟服务器请求的示例,如下例所示https://flutter-academy.com/flutter-listview-infinite-scrolling/ https://flutter-academy.com/flutter-listview-infinite-scrolling/
有人遇到过同样的问题或知道如何解决它吗?