Observe changes for key in Firebase database (async/await)

Swift, Async/await, Firebase

Observe changes for key in Firebase database using Swift's async/await

import FirebaseDatabase
import FirebaseDatabaseSwift

public extension DatabaseQuery {
  func observe(_ eventType: DataEventType) -> AsyncThrowingStream<DataSnapshot, Error> {
    AsyncThrowingStream { continuation in
      let handle = observe(
        eventType,
        with: { snapshot in
          continuation.yield(snapshot)
        },
        withCancel: { error in
          continuation.finish(throwing: error)
        }
      )
      continuation.onTermination = { [unowned self] _ in
        removeObserver(withHandle: handle)
      }
    }
  }
}

How to use?

do {
  let ref = Database.database().reference().child("foo")
  
  // Observe child added
  for try await snapshot in ref.observe(.childAdded) {
    print("Child added: \(snapshot.value)")
  }
  
  // Observe child changed
  for try await snapshot in ref.observe(.childChanged) {
    print("Child changed: \(snapshot.value)")
  }
  
  // Observe child moved
  for try await snapshot in ref.observe(.childMoved) {
    print("Child moved: \(snapshot.value)")
  }
  
  // Observe child removed
  for try await snapshot in ref.observe(.childRemoved) {
    print("Child removed: \(snapshot.value)")
  }
  
  // Observe any changes
  for try await snapshot in ref.observe(.value) {
    print("Child removed: \(snapshot.value)")
  }
} catch {
  print("Observing failed with error: \(error)")
}