我使用flutter创建了一个聊天应用程序并将数据存储在Firebase中。Firebase包含两个集合。一个集合包含用户详细信息，另一个集合包含与其他用户的用户聊天。我想合并两个集合详细信息。如何获取其他存储在用户集合中的用户详细信息？ 我已经附上了截图。 Firebase collection Flutter code
答案 0 :(得分：1)
我得到了另一个版本的工作，这似乎比我对两个嵌套的构建器的回答要好一些。
在这里，我使用自定义方法隔离了数据加载，使用专用的Message类来保存消息Document和可选的关联用户Document中的信息。
class Message {
final message;
final timestamp;
final uid;
final user;
const Message(this.message, this.timestamp, this.uid, this.user);
}
class ChatList extends StatelessWidget {
Stream<List<Message>> getData() async* {
var messagesStream = Firestore.instance.collection("chat").orderBy("timestamp", descending: true).snapshots();
var messages = List<Message>();
await for (var messagesSnapshot in messagesStream) {
for (var messageDoc in messagesSnapshot.documents) {
var message;
if (messageDoc["uid"] != null) {
var userSnapshot = await Firestore.instance.collection("users").document(messageDoc["uid"]).get();
message = Message(messageDoc["message"], messageDoc["timestamp"], messageDoc["uid"], userSnapshot["name"]);
}
else {
message = Message(messageDoc["message"], messageDoc["timestamp"], "", "");
}
messages.add(message);
}
yield messages;
}
}
@override
Widget build(BuildContext context) {
var streamBuilder = StreamBuilder<List<Message>>(
stream: getData(),
builder: (BuildContext context, AsyncSnapshot<List<Message>> messagesSnapshot) {
if (messagesSnapshot.hasError)
return new Text('Error: ${messagesSnapshot.error}');
switch (messagesSnapshot.connectionState) {
case ConnectionState.waiting: return new Text("Loading...");
default:
return new ListView(
children: messagesSnapshot.data.map((Message msg) {
return new ListTile(
title: new Text(msg.message),
subtitle: new Text(DateTime.fromMillisecondsSinceEpoch(msg.timestamp).toString()
+"\n"+(msg.user ?? msg.uid)),
);
}).toList()
);
}
}
);
return streamBuilder;
}
}
与带有嵌套生成器的解决方案相比，此代码更具可读性，主要是因为数据处理和UI构建器更好地分离了。它还仅为发布消息的用户加载用户文档。不幸的是，如果用户发布了多条消息，它将为每条消息加载文档。我可以添加一个缓存，但是认为这段代码已经完成了一些工作。
答案 1 :(得分：0)
我在我的应用程序中实现了同样的事情。我所做的是使用 Streambuilder 小部件两次，一次是拉取聊天记录，每次聊天都包含一个 sender_id，然后我使用第二个 Stream 构建器中的 Id 来提取用户信息。
检查下面的代码。
这是所有聊天页面：
@override
Widget build(BuildContext context) {
return StreamBuilder(
stream: FirebaseFirestore.instance
.collection('MyChatHeads')
.doc(_onlineUserId)
.collection('Heads')
.orderBy('head_time', descending: true)
.snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Scaffold(
body: Center(
child: SpinKitThreeBounce(
color: Colors.black54,
size: 20.0,
),
),
);
} else {
if (snapshot.data.documents.length == 0) {
return Scaffold(
body: placeHolder(),
);
placeHolder();
} else {
return Scaffold(
floatingActionButton: FloatingActionButton(
onPressed: () {
Navigator.push(
context,
CupertinoPageRoute(
builder: (_) => SearchUsersPage(
userId: _onlineUserId,
),
),
);
},
child: Icon(Icons.contacts_rounded),
foregroundColor: Colors.white,
backgroundColor: Color(0xff47c8b0),
),
body: ListView.builder(
itemCount: snapshot.data.documents.length,
itemBuilder: (context, index) {
DocumentSnapshot myChatHeads = snapshot.data.documents[index];
return chatHeadItem(
index, myChatHeads, snapshot.data.documents.length);
},
),
);
}
}
},
);
}
所有聊天页面中的项目
Widget chatHeadItem(int index, DocumentSnapshot myChatHeads, int length) {
return StreamBuilder(
stream: FirebaseFirestore.instance
.collection('Users')
.where('user_id', isEqualTo: myChatHeads['head_subject'])
.snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Center(
child: SpinKitThreeBounce(
color: Colors.black54,
size: 20.0,
),
);
} else {
if (snapshot.data.documents.length == 0) {
return Container(
child: Padding(
padding: const EdgeInsets.symmetric(
horizontal: 16.0,
),
child: Row(
children: [
CircleAvatar(
radius: 30,
backgroundColor: Colors.green,
child: CircleAvatar(
radius: 28,
backgroundColor: Colors.white,
child: Image(
height: 56,
width: 56,
image: AssetImage('assets/images/holder.png'),
fit: BoxFit.cover,
),
),
),
SizedBox(
width: 10,
),
Flexible(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
SizedBox(
height: 10,
),
Text(
'User not found',
style: GoogleFonts.quicksand(
color: Colors.black87,
fontWeight: FontWeight.bold,
fontSize: 16.0,
letterSpacing: .5,
),
),
//setCompanyName(myInterviews),
SizedBox(
height: 4.0,
),
InkWell(
onTap: () {
Navigator.push(
context,
CupertinoPageRoute(
builder: (_) => ChatsEngagePage(
userId: _onlineUserId,
secondUserId: myChatHeads['head_subject'],
),
),
);
},
child: Text(
'${myChatHeads['head_last_message']}',
maxLines: 2,
overflow: TextOverflow.ellipsis,
style: GoogleFonts.quicksand(
color: Colors.black87,
fontSize: 16.0,
letterSpacing: .5,
),
),
),
SizedBox(
height: 10,
),
],
),
),
],
),
),
);
} else {
DocumentSnapshot secondUserInfo = snapshot.data.documents[0];
return Container(
//color: Colors.green,
child: Padding(
padding: const EdgeInsets.symmetric(
horizontal: 16.0,
),
child: Column(
children: [
index == 0
? SizedBox(
height: 6,
)
: SizedBox(
height: 0,
),
InkWell(
onTap: () {
Navigator.push(
context,
CupertinoPageRoute(
builder: (_) => ChatsEngagePage(
userId: _onlineUserId,
secondUserId: myChatHeads['head_subject'],
userName: secondUserInfo['user_name'],
userImage: secondUserInfo['user_image'],
),
),
);
},
child: Row(
children: [
InkWell(
onTap: () {
Navigator.push(
context,
CupertinoPageRoute(
builder: (_) => PublicProfilePage(
userId: _onlineUserId,
secondUserId: secondUserInfo['user_id'],
),
),
);
},
child: CachedNetworkImage(
imageUrl: secondUserInfo['user_image'],
imageBuilder: (context, imageProvider) =>
CircleAvatar(
radius: 30,
backgroundColor: Colors.green,
child: CircleAvatar(
radius: 28,
backgroundColor: Colors.white,
backgroundImage: imageProvider,
),
),
placeholder: (context, url) => CircleAvatar(
radius: 30,
backgroundColor: Colors.green,
child: CircleAvatar(
radius: 28,
backgroundColor: Colors.white,
backgroundImage: AssetImage(
'assets/images/holder.png',
),
),
),
errorWidget: (context, url, error) =>
CircleAvatar(
radius: 30,
backgroundColor: Colors.green,
child: CircleAvatar(
radius: 28,
backgroundColor: Colors.white,
backgroundImage: AssetImage(
'assets/images/holder.png',
),
),
),
),
),
SizedBox(
width: 10,
),
Flexible(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
SizedBox(
height: 10,
),
Row(
mainAxisAlignment:
MainAxisAlignment.spaceBetween,
children: [
Flexible(
child: Text(
'${secondUserInfo['user_name']}',
style: GoogleFonts.quicksand(
color: Colors.black87,
fontWeight: FontWeight.bold,
fontSize: 16.0,
letterSpacing: .5,
),
maxLines: 1,
overflow: TextOverflow.ellipsis,
),
),
Text(
timeAgoSinceDateEn(
DateTime.fromMillisecondsSinceEpoch(
myChatHeads['head_time'],
).toString(),
),
//postSnap['press_formatted_date'],
style: GoogleFonts.quicksand(
textStyle: TextStyle(
fontSize: 14.0,
color: Colors.grey,
),
),
),
],
),
//setCompanyName(myInterviews),
SizedBox(
height: 4.0,
),
Text(
'${myChatHeads['head_last_message']}',
maxLines: 2,
overflow: TextOverflow.ellipsis,
style: GoogleFonts.quicksand(
color: Colors.black87,
fontSize: 16.0,
letterSpacing: .5,
),
),
SizedBox(
height: 10,
),
],
),
),
],
),
),
index == length - 1
? Container()
: Divider(
//color: Colors.red,
),
index == length - 1
? SizedBox(
height: 4,
)
: SizedBox(
height: 0,
),
],
),
),
);
}
}
},
);
}
这是一个单独的聊天页面：
body: Stack(
children: [
Container(
height: double.infinity,
width: double.infinity,
color: Colors.grey[100],
child: StreamBuilder(
stream: FirebaseFirestore.instance
.collection('Chats')
.doc(userId)
.collection(secondUserId)
.orderBy('message_time', descending: true)
.snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Center(
child: Padding(
padding: const EdgeInsets.symmetric(vertical: 16),
child: SpinKitThreeBounce(
color: Colors.black54,
size: 20.0,
),
),
);
} else {
if (snapshot.data.documents.length == 0) {
return Center(
child: Padding(
padding: const EdgeInsets.symmetric(vertical: 16),
child: Container(
width: MediaQuery.of(context).size.width / 3,
child: Image(
image: AssetImage('assets/images/empty.png'),
width: double.infinity,
),
),
),
);
} else {
return Padding(
padding: const EdgeInsets.symmetric(horizontal: 8.0),
child: ListView.builder(
shrinkWrap: true,
reverse: true,
// physics: NeverScrollableScrollPhysics(),
// primary: false,
padding: EdgeInsets.zero,
itemCount: snapshot.data.documents.length,
itemBuilder: (context, index) {
DocumentSnapshot myPresses =
snapshot.data.documents[index];
if (myPresses['message_owner'] == userId) {
return Padding(
padding: index == 0
? EdgeInsets.only(bottom: height + 26)
: EdgeInsets.only(bottom: 0),
child: Bubble(
margin: BubbleEdges.only(top: 10),
nip: BubbleNip.rightTop,
alignment: Alignment.topRight,
color: Colors.lightGreen[100],
child: Column(
crossAxisAlignment: CrossAxisAlignment.end,
children: [
Text(
myPresses['message_body'],
style: GoogleFonts.quicksand(
fontSize: 16,
color: Colors.black87,
),
),
Text(
timeAgoSinceDateEn(
DateTime.fromMillisecondsSinceEpoch(
myPresses['message_time'],
).toString(),
),
//postSnap['press_formatted_date'],
style: GoogleFonts.quicksand(
textStyle: TextStyle(
fontSize: 14.0,
color: Colors.grey,
),
),
),
],
),
),
);
} else {
return Padding(
padding: index == 0
? EdgeInsets.only(bottom: height + 26)
: EdgeInsets.only(bottom: 0),
child: Bubble(
margin: BubbleEdges.only(top: 10),
alignment: Alignment.topLeft,
nip: BubbleNip.leftTop,
color: Color(0xffd4eaf5),
child: Column(
crossAxisAlignment: CrossAxisAlignment.end,
children: [
Text(
myPresses['message_body'],
style: GoogleFonts.quicksand(
fontSize: 16,
color: Colors.black87,
),
),
Text(
timeAgoSinceDateEn(
DateTime.fromMillisecondsSinceEpoch(
myPresses['message_time'],
).toString(),
),
//postSnap['press_formatted_date'],
style: GoogleFonts.quicksand(
textStyle: TextStyle(
fontSize: 14.0,
color: Colors.grey,
),
),
),
],
),
),
);
}
},
),
);
}
}
},
),
),
Positioned(
bottom: 10.0,
left: 10.0,
right: 10.0,
child: MeasuredSize(
onChange: (Size size) {
setState(() {
print(size);
height = size.height;
});
},
child: Container(
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.all(
Radius.circular(0),
),
boxShadow: [
BoxShadow(
color: Colors.grey.withOpacity(0.4),
spreadRadius: 2,
blurRadius: 3,
offset: Offset(0, 2), // changes position of shadow
),
],
),
//height: 58,
child: Padding(
padding: const EdgeInsets.symmetric(
horizontal: 8.0, vertical: 8.0),
child: Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: [
Expanded(
child: TextFormField(
controller: textEditingController,
keyboardType: TextInputType.multiline,
textCapitalization: TextCapitalization.sentences,
maxLength: 800,
maxLines: null,
style: GoogleFonts.quicksand(
textStyle: TextStyle(
fontSize: 14.0,
color: Colors.black54,
letterSpacing: .5,
),
),
decoration: InputDecoration(
labelText: 'Message',
contentPadding: const EdgeInsets.symmetric(
horizontal: 0.0, vertical: 0.0),
errorStyle: TextStyle(color: Colors.brown),
),
onChanged: (val) {
setState(() => _message = val);
},
validator: (val) =>
val.length < 1 ? ('Too short') : null,
),
),
SizedBox(
width: 16,
),
InkWell(
onTap: () {
_submitMessage();
},
child: Padding(
padding:
const EdgeInsets.only(right: 8.0, bottom: 20),
child: Icon(
Icons.send_rounded,
color: Colors.green,
),
),
),
],
),
),
),
),
),
],
),