Flutter:Firebase从userID读取数据

Question

我正在用Flutter构建一个ToDo应用程序。现在我添加了一个匿名登录，这样每个设备都有自己的ToDos。但所有设备仍然显示相同的ToDos。我试着添加.dococument(user.uid(，但没有成功，因为"user"的下划线是红色的。那么我怎么能只读取这个设备上一个用户的数据呢？我遇到的另一个问题是ToDo不会添加到数据库中userID文档中现有的文档中，否则它只会更新"旧"文档。这是我的代码：(如果你需要代码的另一部分，请告诉我(

class HomePage extends StatefulWidget {
@override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {

String input = "";

createTodos() async{
FirebaseUser user = await FirebaseAuth.instance.currentUser();
DocumentReference documentReference =
Firestore.instance.collection("MyTodos").document(user.uid);
//Map
Map<String, String> todos = {"todoTitle": input};
documentReference.setData(todos).whenComplete(() {
print("$input created");
});
}
deleteTodos(item) {
DocumentReference documentReference =
Firestore.instance.collection("users").document();

documentReference.delete().whenComplete(() {
print("$item deleted");
});
}
moveTodos(item) {
DocumentReference documentReference =
Firestore.instance.collection("users").document(item);
//Map
Map<String, String> todos = {"todoMove": item};
documentReference.setData(todos).whenComplete(() {
print("$input moved");
});
}

@override
Widget build(BuildContext context) {
return Scaffold(
floatingActionButton: FloatingActionButton(
onPressed: () {
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
backgroundColor: Colors.grey[300],
title: Text('Add ToDo',
style: TextStyle(fontWeight: FontWeight.bold),),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(15)
),
content: TextField(
onChanged: (String value) {
input = value;
},
),
actions: <Widget>[
FlatButton(
onPressed: () {
createTodos();
Navigator.of(context).pop();
},
child: Text('Add'))
],
);
});
},
child: Container(
width: 200,
height: 200,
child: Icon(Icons.add, color: Colors.grey[700],),
decoration: BoxDecoration(
color: Colors.grey[300],
borderRadius: BorderRadius.all(Radius.circular(50)),
boxShadow: [
BoxShadow(
color: Colors.grey[500],
offset: Offset(4.0, 4.0),
blurRadius: 15.0,
spreadRadius: 1.0
),
BoxShadow(
color: Colors.white,
offset: Offset(-4.0, -4.0),
blurRadius: 15.0,
spreadRadius: 1.0
),
]
),
)
),
body: StreamBuilder(
stream: Firestore.instance.collection("users").snapshots(),
builder: (context, snapshots){
if(snapshots.data == null) return CircularProgressIndicator();
return ListView.builder(
shrinkWrap: true,
itemCount: snapshots.data.documents.length,
itemBuilder: (context, index) {
DocumentSnapshot documentSnapshot = snapshots.data.documents[index];
return Dismissible(
background: Container(
color: Colors.green,
alignment: Alignment(-0.9, 0),
child: Icon(Icons.check, color: Colors.white,),
),
secondaryBackground: Container(
color: Colors.red,
alignment: Alignment(0.9, 0),
child: Icon(Icons.delete, color: Colors.white,),
),
onDismissed: (direction) {
if (direction == DismissDirection.startToEnd) {
moveTodos(documentSnapshot["todoTitle"]);
deleteTodos(documentSnapshot["todoTitle"]);
} else
if (direction == DismissDirection.endToStart) {
deleteTodos(documentSnapshot["todoTitle"]);
}
},
key: Key(documentSnapshot["todoTitle"]),
child: Container(
margin: EdgeInsets.all(8),
child: Card(
margin: EdgeInsets.zero,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(10)
),
color: Colors.grey[300],
child: ListTile(
title: Text(documentSnapshot["todoTitle"] ?? "No ToDos yet!"),
trailing: Wrap(
children: <Widget>[
IconButton(
icon: Icon(Icons.check),
color: Colors.green,
onPressed: (){
moveTodos(documentSnapshot["todoTitle"]);
deleteTodos(documentSnapshot["todoTitle"]);
} ),
IconButton(
icon: Icon(Icons.delete),
color: Colors.red,
onPressed: (){
deleteTodos(documentSnapshot["todoTitle"]);
} ),
],
)
),
),
decoration: BoxDecoration(
color: Colors.grey[300],
borderRadius: BorderRadius.all(Radius.circular(10)),
boxShadow: [
BoxShadow(
color: Colors.grey[500],
offset: Offset(4.0, 4.0),
blurRadius: 15.0,
spreadRadius: 1.0
),
BoxShadow(
color: Colors.white,
offset: Offset(-4.0, -4.0),
blurRadius: 15.0,
spreadRadius: 1.0
),
]
),
),
);
});
}),
backgroundColor: Colors.grey[300],
);
}
}

Answer 1

问题出现在下面的行中：

stream: Firestore.instance.collection("users").snapshots(),

它基本上抓取"用户"集合中的所有内容，并将其显示给每个人。您只需要在从Firestore获取数据时添加一个特定于用户的筛选器。您可能想将过滤器添加为：

stream: Firestore.instance.collection("users")
.where('userId', isEqualTo: user.uid)
.snapshots()