Dart 向ListView添加卡
我正在尝试获取的列表，并尝试使用Dart 向ListView添加卡,dart,flutter,Dart,Flutter,我正在尝试获取的列表，并尝试使用扩展的小部件，但出现了溢出错误 我的代码： new Expanded( child: StreamBuilder( stream: Firestore.instance.collection('baby').snapshots(), builder: (context, snapshot) { if (!snapshot.hasData) return const Text('Loadin
扩展的溢出new Expanded(
child: StreamBuilder(
stream: Firestore.instance.collection('baby').snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) return const Text('Loading...');
return ListView.builder(
itemCount: snapshot.data.documents.length,
padding: const EdgeInsets.only(top: 10.0),
itemExtent: 25.0,
itemBuilder: (context, index) {
DocumentSnapshot ds = snapshot.data.documents[index];
return //Text(" ${ds['name']} ${ds['vote']}");
Card(
child: Expanded(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
const ListTile(
leading: const Icon(Icons.album),
title: const Text('The Enchanted Nightingale'),
subtitle: const Text('Music by Julie Gable. Lyrics by Sidney Stein.'),
),
new ButtonTheme.bar( // make buttons use the appropriate styles for cards
child: ButtonBar(
children: <Widget>[
FlatButton(
child: const Text('BUY TICKETS'),
onPressed: () { /* ... */ },
),
FlatButton(
child: const Text('LISTEN'),
onPressed: () { /* ... */ },
),
],
),
),
],
),
),
);
});
})),
新扩展(
孩子：StreamBuilder(
流：Firestore.instance.collection（'baby'）.snapshots（），
生成器：（上下文，快照）{
如果（！snapshot.hasData）返回常量文本（'Loading…'）；
返回ListView.builder(
itemCount:snapshot.data.documents.length，
填充：仅限常量边集（顶部：10.0），
项目范围：25.0，
itemBuilder：（上下文，索引）{
DocumentSnapshot ds=snapshot.data.documents[索引]；
return//Text（${ds['name']}${ds['vote']}）；
卡片(
儿童：扩大(
子：列(
mainAxisSize:mainAxisSize.min，
儿童：[
常量列表(
前导：const图标（Icons.album），
标题：康斯特文本（“迷人的夜莺”），
字幕：康斯特文本（“朱莉·盖博的音乐，西德尼·斯坦的歌词”），
),
new ButtonTheme.bar（//使按钮对卡片使用适当的样式
孩子：巴顿巴(
儿童：[
扁平按钮(
孩子：const Text（‘买票’），
按下：（）{/*…*/}，
),
扁平按钮(
child:const Text（'LISTEN'），
按下：（）{/*…*/}，
),
],
),
),
],
),
),
);
});
})),
不正确地使用了ParentDataWidget。这是我得到的输出屏幕： 如果我移除了
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'BabyModel.dart';
import 'BabyCard.dart';
void main() => runApp(MyApp(
textInput: Text("Text Widget"),
));
class MyApp extends StatefulWidget {
final Widget textInput;
MyApp({this.textInput});
@override
State<StatefulWidget> createState() => MyAppState();
}
class MyAppState extends State<MyApp> {
bool checkBoxValue = false;
@override
Widget build(BuildContext ctxt) {
return StreamBuilder(
stream: Firestore.instance.collection('baby').snapshots(),
builder: (_, AsyncSnapshot<QuerySnapshot> snapshot) {
var documents = snapshot.data?.documents ?? [];
var baby =
documents.map((snapshot) => BabyData.from(snapshot)).toList();
return BabyPage(baby);
},
);
}
}
class BabyPage extends StatefulWidget {
final List<BabyData> allBaby;
BabyPage(this.allBaby);
@override
State<StatefulWidget> createState() {
return BabyPageState();
}
}
class BabyPageState extends State<BabyPage> {
@override
Widget build(BuildContext context) {
// var filteredBaby = widget.allFish.where((BabyData data) {
// data.name = 'Dana';
// }).toList();
return MaterialApp(
home: SafeArea(
child: Scaffold(
body: Container(
child: ListView.builder(
itemCount: widget.allBaby.length,
padding: const EdgeInsets.only(top: 10.0),
itemBuilder: (context, index) {
return BabyCard(widget.allBaby[index]);
})
),
)));
}
}
import 'package:cloud_firestore/cloud_firestore.dart';
class BabyData {
final DocumentReference reference;
String name;
int vote;
BabyData.data(this.reference,
[this.name,
this.vote]) {
// Set these rather than using the default value because Firebase returns
// null if the value is not specified.
this.name ??= 'Frank';
this.vote ??= 7;
}
factory BabyData.from(DocumentSnapshot document) => BabyData.data(
document.reference,
document.data['name'],
document.data['vote']);
void save() {
reference.setData(toMap());
}
Map<String, dynamic> toMap() {
return {
'name': name,
'vote': vote,
};
}
}
import 'package:flutter/material.dart';
import 'BabyModel.dart';
class BabyCard extends StatefulWidget {
final BabyData baby;
BabyCard(this.baby);
@override
State<StatefulWidget> createState() {
return BabyCardState(baby);
}
}
class BabyCardState extends State<BabyCard> {
BabyData baby;
String renderUrl;
BabyCardState(this.baby);
Widget get babyCard {
return
new Card(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
ListTile(
leading: const Icon(Icons.album),
title: Text('The ${baby.name} is having:'),
subtitle: Text('${baby.vote} Votes.'),
),
new ButtonTheme.bar( // make buttons use the appropriate styles for cards
child: new ButtonBar(
children: <Widget>[
new FlatButton(
child: const Text('Thumb up'),
onPressed: () { /* ... */ },
),
new FlatButton(
child: const Text('Thumb down'),
onPressed: () { /* ... */ },
)]))]));
}
@override
Widget build(BuildContext context) {
return new Container(
child: babyCard,
);
}
}
ListView(
children: <Widget>[
Card(child: ListTile(title: Text('One-line ListTile'))),
Card(
child: ListTile(
leading: FlutterLogo(),
title: Text('One-line with leading widget'),
),
),
Card(
child: ListTile(
title: Text('One-line with trailing widget'),
trailing: Icon(Icons.more_vert),
),
),
Card(
child: ListTile(
leading: FlutterLogo(),
title: Text('One-line with both widgets'),
trailing: Icon(Icons.more_vert),
),
),
Card(
child: ListTile(
title: Text('One-line dense ListTile'),
dense: true,
),
),
Card(
child: ListTile(
leading: FlutterLogo(size: 56.0),
title: Text('Two-line ListTile'),
subtitle: Text('Here is a second line'),
trailing: Icon(Icons.more_vert),
),
),
Card(
child: ListTile(
leading: FlutterLogo(size: 72.0),
title: Text('Three-line ListTile'),
subtitle:
Text('A sufficiently long subtitle warrants three lines.'),
trailing: Icon(Icons.more_vert),
isThreeLine: true,
),
),
Card(
child: InkWell(
splashColor: Colors.blue.withAlpha(30),
onTap: () {
print('Card tapped.');
},
child: Container(
width: 300,
height: 100,
child: Center(
child: Text(
'When tapped this Cards InkWell displays an ink splash that fills the entire card',
),
),
),
)),
],
)