更新时间:2022-11-15 16:18:06
我发布了一个类似的问题,后来找到了一个解决方案:将itemBuilder返回的小部件设置为有状态,并在其中使用FutureBuilder。
I posted a similar question and later found a solution: make the widget returned by the itemBuilder stateful and use a FutureBuilder in it.
对StreamBuilder中每个DocumentSnapshot的附加查询
这是我的代码。对于您的情况,您想使用一个新的有状态小部件而不是ListTile,因此可以添加FutureBuilder来调用异步函数。
Here's my code. In your case, your would want to use a new Stateful widget instead of ListTile, so you can add the FutureBuilder to call an async function.
StreamBuilder(
stream: Firestore.instance
.collection("messages").snapshots(),
builder: (context, snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
case ConnectionState.waiting:
return Center(
child: PlatformProgressIndicator(),
);
default:
return ListView.builder(
reverse: true,
itemCount: snapshot.data.documents.length,
itemBuilder: (context, index) {
List rev = snapshot.data.documents.reversed.toList();
ChatMessageModel message = ChatMessageModel.fromSnapshot(rev[index]);
return ChatMessage(message);
},
);
}
},
)
class ChatMessage extends StatefulWidget {
final ChatMessageModel _message;
ChatMessage(this._message);
@override
_ChatMessageState createState() => _ChatMessageState(_message);
}
class _ChatMessageState extends State<ChatMessage> {
final ChatMessageModel _message;
_ChatMessageState(this._message);
Future<ChatMessageModel> _load() async {
await _message.loadUser();
return _message;
}
@override
Widget build(BuildContext context) {
return Container(
margin: const EdgeInsets.symmetric(horizontal: 10.0, vertical: 10.0),
child: FutureBuilder(
future: _load(),
builder: (context, AsyncSnapshot<ChatMessageModel>message) {
if (!message.hasData)
return Container();
return Row(
children: <Widget>[
Container(
margin: const EdgeInsets.only(right: 16.0),
child: GestureDetector(
child: CircleAvatar(
backgroundImage: NetworkImage(message.data.user.pictureUrl),
),
onTap: () {
Navigator.of(context)
.push(MaterialPageRoute(builder: (context) =>
ProfileScreen(message.data.user)));
},
),
),
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
message.data.user.name,
style: Theme.of(context).textTheme.subhead,
),
Container(
margin: const EdgeInsets.only(top: 5.0),
child: _message.mediaUrl != null
? Image.network(_message.mediaUrl, width: 250.0)
: Text(_message.text))
],
),
)
],
);
},
),
);
}
}
class ChatMessageModel {
String id;
String userId;
String text;
String mediaUrl;
int createdAt;
String replyId;
UserModel user;
ChatMessageModel({String text, String mediaUrl, String userId}) {
this.text = text;
this.mediaUrl = mediaUrl;
this.userId = userId;
}
ChatMessageModel.fromSnapshot(DocumentSnapshot snapshot) {
this.id = snapshot.documentID;
this.text = snapshot.data["text"];
this.mediaUrl = snapshot.data["mediaUrl"];
this.createdAt = snapshot.data["createdAt"];
this.replyId = snapshot.data["replyId"];
this.userId = snapshot.data["userId"];
}
Map toMap() {
Map<String, dynamic> map = {
"text": this.text,
"mediaUrl": this.mediaUrl,
"userId": this.userId,
"createdAt": this.createdAt
};
return map;
}
Future<void> loadUser() async {
DocumentSnapshot ds = await Firestore.instance
.collection("users").document(this.userId).get();
if (ds != null)
this.user = UserModel.fromSnapshot(ds);
}
}