Firebase Listener Called Multiple Times When Data Change SwiftUI

Question

I have three listeners

Get Visible Data to all user
Get Data Between two dates
Get All Data

However, When any Data change user table the Listener call automatically 4-5 times.

 func listenData() -> ListenerRegistration { let listener = db.collection("user") .whereField("FirstRow", isGreaterThanOrEqualTo: "FirstRow") .whereField("lastRow", isLessThanOrEqualTo: "lastRow") .addSnapshotListener { querySnapshot, error in if let error = error { print("listener error: \(error.localizedDescription)") return } if let snapshot = querySnapshot { print("Without For Each = Data") snapshot.documentChanges.forEach { diff in print("For Each = Data") } print("listen Public Rides Loop Done") } } return listener }

Question: How to Listener call once time when user change the data?

Can someone please explain to me How to Listener call once time only?

Any help would be greatly appreciated.

Thanks in advance.

If you want to get the data only once, consider using get() instead of addSnapshotListener as shown in firebase.google.com/docs/firestore/query-data/get-data — Frank van Puffelen
– Frank van Puffelen, Commented Nov 18, 2021 at 14:43
@FrankvanPuffelen get() automatically call when user change the data or need to call again? — Sham Dhiman
– Sham Dhiman, Commented Nov 18, 2021 at 14:49
You will need to call it again if you want to load the data again. If you want to detect changes, you will have to use onSnapshot. But that will always also give you the initial snapshot of the data in the database. If you don't need that for your use-case, you will either have to ignore it in your application code, or you will have to come up with a query that only returns the documents you're interested in (for example by including a timestamp in there). There is no way to tell Firebase to skip the initial payload. — Frank van Puffelen
– Frank van Puffelen, Commented Nov 18, 2021 at 15:36
Sorry @FrankvanPuffelen for late reply. I was little busy in my code. thank you for your help and advice — Sham Dhiman
– Sham Dhiman, Commented Nov 26, 2021 at 6:39

Frank van Puffelen · Accepted Answer · 2021-11-18 15:39:32Z

Firestore's onSnapshot will always also give you the initial snapshot of the data in the database. There is no way to tell the API to skip this initial snapshot.

If you don't need the initial data for your use-case, you will either have to ignore it in your application code, or you will have to come up with a query that only returns the documents you're interested in. That last one has been covered a few times before, so I recommend looking at the answers to these questions.

If you want to stop listening for more updates after the first change, you can detach the listener at that point.

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