Flutter 将多个 FireStore 流与 Rxdart 相结合

Question

我想我需要在某个地方合并它，但我找不到如何以及在哪里。我想在流构建器中使用？我把你带到这里来等你的帮助。

getCombinedMatches(uid) {
return Firestore.instance
.collection('matches')
.where('match', arrayContains: uid)
.snapshots()
.map((convert) {
return convert.documents.map((f) {
Observable<Matches> match = f.reference
.snapshots()
.map<Matches>((document) => Matches.fromMap(document.data));
Observable<User> user = Firestore.instance
.collection("users")
.document(uid)
.snapshots()
.map<User>((document) => User.fromMap(document.data));
Observable<Message> message = Firestore.instance
.collection('matches')
.document(f.documentID)
.collection("chat")
.orderBy('dater', descending: true)
.limit(1)
.snapshots()
.expand((snapShot) => snapShot.documents)
.map<Message>((document) => Message.fromMap(document.data));
return Observable.combineLatest3(match, user, message,
(matches, user, message) => CombinedStream(matches, user, message));
});
});
}

Answer 1

添加此代码的最后一个操作

getCombinedMatches(uid) {
return Observable(Firestore.instance
.collection('matches')
.where('match', arrayContains: uid)
.snapshots())
.map((convert) {
return convert.documents.map((f) {
Stream<Matches> match = f.reference
.snapshots()
.map<Matches>((document) => Matches.fromMap(document.data));
Stream<User> user = Firestore.instance
.collection("users")
.document(uid)
.snapshots()
.map<User>((document) => User.fromMap(document.data));
Stream<Message> message = Firestore.instance
.collection('matches')
.document(f.documentID)
.collection("chat")
.orderBy('dater', descending: true)
.limit(1)
.snapshots()
.expand((snapShot) => snapShot.documents)
.map<Message>((document) => Message.fromMap(document.data));
return Observable.combineLatest3(match, user, message,
(matches, user, message) => CombinedStream(matches, user, message));
});
}).switchMap((observables) {
return observables.length > 0
? Observable.combineLatestList(observables)
: Observable.just([]);
});

}

Answer 2

如果合并流，流构建器将仅显示合并流中的 LAST 事件。我相信你可以做这样的事情：

// snapshotList will be your AsyncSnapshot. snapshotList.data will be your List<QuerySnapshot>
StreamBuilder<List<QuerySnapshot>>(
stream: streamList,
builder: (BuildContext context, AsyncSnapshot<List<QuerySnapshot>> snapshotList) {
snapshotList.data.forEach((document) {
return something
}
}
)

让我知道这是否有帮助