add-document.kt

fun Team.addScout() {
    val scoutRef: DocumentReference = FirebaseFirestore.getInstance()
        .collection("teams")
        .document(id /* Field in Team */)
        .collection("scouts")
        .document() // Creating a document ref with a truly random id

    scoutRef.set(Scout(scoutRef.id, templateId))
    firestoreBatch {
        val metricsRef = scoutRef.collection("metrics")
        dataGatheredFromAQuery.forEach { metric ->
            set(metricsRef.document(metric.id), metric)
        }
    }
}

inline fun firestoreBatch(transaction: WriteBatch.() -> Unit): Task<Void> = FirebaseFirestore.getInstance().batch().run {
    transaction()
    commit()
}