Flutter 类别';列表<;文档快照>';没有实例getter';文件';
我正在尝试实现一种功能,该应用程序在网格视图中显示除当前用户之外的所有用户详细信息。我一直在尝试将Flutter 类别';列表<;文档快照>';没有实例getter';文件';,flutter,google-cloud-firestore,stream,Flutter,Google Cloud Firestore,Stream,我正在尝试实现一种功能,该应用程序在网格视图中显示除当前用户之外的所有用户详细信息。我一直在尝试将快照分配给\u流,然后在StreamBuilder()中应用\u流值。但它却抛出了一个错误 Database _database = Database(); Stream _stream; String currentUserId; @override void initState() { getCurrentUserId(); //currentUserId gets its value
快照
分配给\u流
,然后在StreamBuilder()
中应用\u流
值。但它却抛出了一个错误
Database _database = Database();
Stream _stream;
String currentUserId;
@override
void initState() {
getCurrentUserId(); //currentUserId gets its value here
getAllUsers();
super.initState();
}
getAllUsers() async {
Stream<QuerySnapshot> snapshots = await _database.getAllUsers();
_stream = snapshots.map((querySnapshot) => querySnapshot.documents.where((documentSnapshot)
=> documentSnapshot.data["userId"] != currentUserId
).toList())
}
//..
StreamBuilder(
stream: _stream,
builder: (context, snapshot) {
if (snapshot.data != null)
//..
}
//..
)
数据库类
getAllUsers() async {
return await _firestore.collection("users").snapshots();
}
例外情况
════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The following NoSuchMethodError was thrown building StreamBuilder<dynamic>(dirty, state: _StreamBuilderBaseState<dynamic, AsyncSnapshot<dynamic>>#6e31f):
Class 'List<DocumentSnapshot>' has no instance getter 'documents'.
Receiver: Instance(length:2) of '_GrowableList'
Tried calling: documents
The relevant error-causing widget was:
StreamBuilder<dynamic> file:///Users/suriantosurianto/AndroidStudioProjects/apui/lib/fragments/home_fragment.dart:66:12
When the exception was thrown, this was the stack:
#0 Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
#1 _HomeFragmentState.build.<anonymous closure> (package:apui/fragments/home_fragment.dart:80:42)
#2 StreamBuilder.build (package:flutter/src/widgets/async.dart:509:81)
#3 _StreamBuilderBaseState.build (package:flutter/src/widgets/async.dart:127:48)
#4 StatefulElement.build (package:flutter/src/widgets/framework.dart:4619:28)
...
════════════════════════════════════════════════════════════════════════════════════════════════════
════════ widgets库捕获到异常═══════════════════════════════════════════════════════
生成StreamBuilder时引发了以下NoSuchMethodError(脏,状态:_StreamBuilderBaseState#6e31f):
类“List”没有实例获取程序“documents”。
接收者:“\u GrowtableList”的实例(长度:2)
尝试呼叫:文档
导致错误的相关小部件是:
StreamBuilderfile:///Users/suriantosurianto/AndroidStudioProjects/apui/lib/fragments/home_fragment.dart:66:12
引发异常时,这是堆栈:
#0 Object.noSuchMethod(省道:核心补片/对象补片。省道:53:5)
#1\u HomeFragmentState.build。(包装:apui/fragments/home_fragments.dart:80:42)
#2 StreamBuilder.build(包:flatter/src/widgets/async.dart:509:81)
#3\u StreamBuilderBaseState.build(包:flatter/src/widgets/async.dart:127:48)
#4 StatefulElement.build(包:flatter/src/widgets/framework.dart:4619:28)
...
════════════════════════════════════════════════════════════════════════════════════════════════════
我们不知道该错误指向的是哪一行,但是如果我理解正确,原因可能是StreamBuilder
属性流
的类型应该是流
类()
似乎\u stream
是使用toList
方法()从stream
创建的列表。我会尝试删除这个toList
方法,看看会发生什么
我希望这会有帮助
// NEW
_stream = snapshots.map((querySnapshot) => querySnapshot.documents.where((documentSnapshot)
=> documentSnapshot.data["userId"] != currentUserId
).toList() as QuerySnapshot);
这里的querySnapshot
是一个列表
您可能必须使用querySnapshot。where()
正如其他人指出的,querySnapshot是一个列表,而不是文档快照
,因此您不能使用getter.documents
(该getter仅用于文档快照
,而不是列表
),这是因为我们正在检索除当前用户之外的每个用户的文档快照
(每个用户都有文档快照
,因此也有列表
)
如果要返回List
类型的流,则
_stream = snapshots
.map<List<DocumentSnapshot>>((querySnapshot) =>
querySnapshot.where((documentSnapshot) =>
documentSnapshot.data["userId"] != currentUserId)
);
\u流=快照
.map((querySnapshot)=>
querySnapshot.where((documentSnapshot)=>
documentSnapshot.data[“userId”!=currentUserId)
);
错误告诉您querySnapshot
是一个列表
,而不是querySnapshot
。因此,您必须将其视为一个列表。您能详细说明一下吗?\u stream
不是列表,根据\u stream.runtimeType
,它是一个\u MapStream
,无论toList()
方法如何,它都不起作用。为什么querySnapshot是一个列表??
_stream = snapshots
.map<List<DocumentSnapshot>>((querySnapshot) =>
querySnapshot.where((documentSnapshot) =>
documentSnapshot.data["userId"] != currentUserId)
);