Reading Firebase Database as Kotlin coroutines

FirebaseCoroutinesExtensions.kt

/*

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

WARNING!!!
NO, SERIOUSLY. REAL WARNING!!!


!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


This snippet was written years ago, when coroutines were experimental and I had no clue how did they work.
But for some reason my gist keep showing up first in some Google searches.

DO NOT USE THIS CODE.


Now there's official support for adapting Firebase methods to coroutines:
https://github.com/Kotlin/kotlinx.coroutines/tree/master/integration/kotlinx-coroutines-play-services
*/

import com.google.firebase.database.DataSnapshot
import com.google.firebase.database.DatabaseError
import com.google.firebase.database.DatabaseReference
import com.google.firebase.database.ValueEventListener
import kotlinx.coroutines.experimental.CommonPool
import kotlinx.coroutines.experimental.async
import kotlin.coroutines.experimental.suspendCoroutine


suspend fun DatabaseReference.getValue(): DataSnapshot {
    return async(CommonPool) {
        suspendCoroutine<DataSnapshot> { continuation ->
            addListenerForSingleValueEvent(FValueEventListener(
                    onDataChange = { continuation.resume(it) },
                    onError = { continuation.resumeWithException(it.toException()) }
            ))
        }
    }.await()
}

class FValueEventListener(val onDataChange: (DataSnapshot) -> Unit, val onError: (DatabaseError) -> Unit) : ValueEventListener {
    override fun onDataChange(data: DataSnapshot) = onDataChange.invoke(data)
    override fun onCancelled(error: DatabaseError) = onError.invoke(error)
}

A better official implementation, has been released: https://github.com/Kotlin/kotlinx.coroutines/blob/master/integration/kotlinx-coroutines-play-services @Sloy

This official implementation is not for Firebase Database! I've tried

Thanks, great.
The above seems to be for Firebase Firestore, Can similar solution possible for the Firebase realtime database?

Hey, @faisalmohd83 you can use kotlin coroutines Flow API for firebase realtime database. Check out this https://ahsensaeed.com/android-firebase-kotlin-coroutines-flow-api/.