英文:
Google FireStore QuerySnapshot not returning newly added documents?
问题
为了学习目的，我创建了一个Android应用程序，并尝试从Google Firestore获取文档，一开始运行良好，我能够读取数据，但后来当我在Firestore控制台中添加了更多文档后，代码仍然返回给我旧记录。新添加的文档没有在QuerySnapshot中返回。我怀疑可能存在缓存问题，或者是否有任何设置我应该更改以读取最新文档或避免缓存记录？
有什么建议吗？
以下是我考虑阅读文档的代码片段 -
db.collection("posts")
.get()
.addOnCompleteListener(task -> {
if (task.isSuccessful()) {
QuerySnapshot querySnapshot = task.getResult();
// 在快照中遍历文档
for (QueryDocumentSnapshot document : querySnapshot) {
String title = document.getString("title");
// 在日志中打印标题
}
} else {
// 其他情况
}
});
英文:
For learning purposes, I created an android app and tried to fetch documents from Google Firestore, it worked fine and I was able to read data but later, when I added more documents in the Firestore console, the code is running but still returning me old records. Newly added documents are not returned by QuerySnapshot. I doubt, if it could be any cache issue or if is there any setting that I should change to read the latest documents or to avoid cached records?
any suggestion?
Below is the code snippet, I was considering reading the Documents -
db.collection("posts")
.get()
.addOnCompleteListener(task -> {
if (task.isSuccessful()) {
QuerySnapshot querySnapshot = task.getResult();
// Iterate over the documents in the snapshot
for (QueryDocumentSnapshot document : querySnapshot) {
String title = document.getString("title");
// printing title in logs
}
} else{
// some else part
}
});
答案1
得分: 2
新添加的文档不会在QuerySnapshot中返回。
这是预期的行为。正如@DougStevenson在他的评论中提到的，当您使用Query#get()时，这是不可能的。这个方法只会一次性读取数据。这意味着您不会收到有关服务器上发生的任何更改的通知。您所寻找的是一个实时监听器。在代码中，这将是：
db.collection("posts").addSnapshotListener(new EventListener<QuerySnapshot>() {
@Override
public void onEvent(@Nullable QuerySnapshot value,
@Nullable FirebaseFirestoreException e) {
if (e != null) {
Log.w(TAG, "监听失败。", e);
return;
}
for (QueryDocumentSnapshot doc : value) {
String title = document.getString("title");
if (title != null) {
Log.d(TAG, title);
}
}
}
});
英文:
> Newly added documents are not returned by QuerySnapshot.
That's the expected behavior. As @DougStevenson mentioned in his comment, that's not possible when you're using Query#get(). This method reads that data only once. This means that you aren't notified about any change that is happening on the server. What you are looking for, is a real-time listener. In code that would be:
db.collection("posts").addSnapshotListener(new EventListener<QuerySnapshot>() {
@Override
public void onEvent(@Nullable QuerySnapshot value,
@Nullable FirebaseFirestoreException e) {
if (e != null) {
Log.w(TAG, "Listen failed.", e);
return;
}
for (QueryDocumentSnapshot doc : value) {
String title = document.getString("title");
if (title != null) {
Log.d(TAG, title);
}
}
}
});
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