Implement firebase-database Kotlin extension.

[rlazo]

No description provided.

[thatfiredev]

nit: maybe use val instead of var here.

[rlazo]

Good catch!. Fixed

[rlazo]

/retest

[vkryachko]

worth inlining into getValue call?

[rlazo]

Good catch, fixed.

[msasikanth]

Also add an extension supporting Kotlin coroutines? I can provide a PR for this separately.

suspend fun <T : Any> Query.await(): T? {
    return suspendCancellableCoroutine { continuation ->
        val eventListener = object : ValueEventListener {
            override fun onDataChange(dataSnap: DataSnapshot) {
                val type = object : GenericTypeIndicator<T>() {}
                continuation.resume(dataSnap.getValue(type))
            }

            override fun onCancelled(dbError: DatabaseError) {
                continuation.resumeWithException(dbError.toException())
            }
        }
        continuation.invokeOnCancellation {
            removeEventListener(eventListener)
        }
        addListenerForSingleValueEvent(eventListener)
    }
}

[msasikanth]

Also add an extension supporting Kotlin coroutines? I can provide a PR for this separately.

suspend fun <T : Any> Query.await(): T? {
    return suspendCancellableCoroutine { continuation ->
        val eventListener = object : ValueEventListener {
            override fun onDataChange(dataSnap: DataSnapshot) {
                val type = object : GenericTypeIndicator<T>() {}
                continuation.resume(dataSnap.getValue(type))
            }

            override fun onCancelled(dbError: DatabaseError) {
                continuation.resumeWithException(dbError.toException())
            }
        }
        continuation.invokeOnCancellation {
            removeEventListener(eventListener)
        }
        addListenerForSingleValueEvent(eventListener)
    }
}

This extension may not work as expected since type is being erased at runtime. In order to fix that class type should be passed as parameter of the function or make the function inline and use reified. I don't think inlining this function is a good idea. So I will be passing the type as a parameter similar to the getValue(T) in DataSnapshot class.

suspend fun <T : Any> Query.await(type: Class<T>): T? {
    return suspendCancellableCoroutine { continuation ->
        val eventListener = object : ValueEventListener {
            override fun onDataChange(dataSnap: DataSnapshot) {
                continuation.resume(dataSnap.getValue(type))
            }

            override fun onCancelled(dbError: DatabaseError) {
                continuation.resumeWithException(dbError.toException())
            }
        }
        continuation.invokeOnCancellation {
            removeEventListener(eventListener)
        }
        addListenerForSingleValueEvent(eventListener)
    }
}

[rlazo]

Also add an extension supporting Kotlin coroutines? I can provide a PR for this separately.

suspend fun <T : Any> Query.await(): T? {
    return suspendCancellableCoroutine { continuation ->
        val eventListener = object : ValueEventListener {
            override fun onDataChange(dataSnap: DataSnapshot) {
                val type = object : GenericTypeIndicator<T>() {}
                continuation.resume(dataSnap.getValue(type))
            }

            override fun onCancelled(dbError: DatabaseError) {
                continuation.resumeWithException(dbError.toException())
            }
        }
        continuation.invokeOnCancellation {
            removeEventListener(eventListener)
        }
        addListenerForSingleValueEvent(eventListener)
    }
}

This extension may not work as expected since type is being erased at runtime. In order to fix that class type should be passed as parameter of the function or make the function inline and use reified. I don't think inlining this function is a good idea. So I will be passing the type as a parameter similar to the getValue(T) in DataSnapshot class.

suspend fun <T : Any> Query.await(type: Class<T>): T? {
    return suspendCancellableCoroutine { continuation ->
        val eventListener = object : ValueEventListener {
            override fun onDataChange(dataSnap: DataSnapshot) {
                continuation.resume(dataSnap.getValue(type))
            }

            override fun onCancelled(dbError: DatabaseError) {
                continuation.resumeWithException(dbError.toException())
            }
        }
        continuation.invokeOnCancellation {
            removeEventListener(eventListener)
        }
        addListenerForSingleValueEvent(eventListener)
    }
}

It's an interesting suggestion @msasikanth If you could provide a PR it would be great. Please, do keep in mind that changes in the API are subject to internal approval. Thanks!

[thatfiredev]

@msasikanth Please let me know when you add that extension so that I can include it on #841 :)

[msasikanth]

@msasikanth Please let me know when you add that extension so that I can include it on #841 :)

Absolutely, once I figure how to setup the project in Android Studio properly. I am having sync and test run issues with it.

[msasikanth]

@rosariopfernandes , @rlazo I have created the PR for the extension

#862