How to handle timeout in queries with Firebase

Question

I noticed that if I execute a query in Firebase and the database server is not reachable, the callback waits just forever (or until the server is reachable again).

Where this behavior is quite natural for the asynchronous approach used, it would nevertheless be useful to have an easy way to specify a timeout so you could inform the user about the status.

Is there such an option and I just missed it - or it really missing? Or how would you solve this problem?

Answer 1

Here's my solution for the Firebase iOS SDK, this may be helpful for others:

extension DatabaseReference {

    func observe(_ eventType: DataEventType, timeout: TimeInterval, with block: @escaping (DataSnapshot?) -> Void) -> UInt {

        var handle: UInt!

        let timer = Timer.scheduledTimer(withTimeInterval: timeout, repeats: false) { (_) in
            self.removeObserver(withHandle: handle)
            block(nil)
        }

        handle = observe(eventType) { (snapshot) in
            timer.invalidate()
            block(snapshot)
        }

        return handle
    }

}

Usage:

database.child("users").observe(.value, timeout: 30) { (snapshot) in

    guard let snapshot = snapshot else {
        // Timeout!
        return
    }

    // We got data within the timeout, so do something with snapshot.value
}

Answer 2

you can manage yourself a timer controller that after x seconds remove the listener to you firebase reference. It's very simple, just one line of code in android for example.

You can see the code for the web (Detaching Callbacks section): https://www.firebase.com/docs/web/guide/retrieving-data.html

or for android (Detaching Callbacks section): https://www.firebase.com/docs/android/guide/retrieving-data.html#section-detaching

same section for IOS ;)