How to get a result from fragment using Navigation Architecture Component?

They have added a fix for this in the 2.3.0-alpha02 release.

If navigating from Fragment A to Fragment B and A needs a result from B:

findNavController().currentBackStackEntry?.savedStateHandle?.getLiveData<Type>("key")?.observe(viewLifecycleOwner) {result ->
    // Do something with the result.
}

If on Fragment B and need to set the result:

findNavController().previousBackStackEntry?.savedStateHandle?.set("key", result)

I ended up creating two extensions for this:

fun Fragment.getNavigationResult(key: String = "result") =
    findNavController().currentBackStackEntry?.savedStateHandle?.getLiveData<String>(key)

fun Fragment.setNavigationResult(result: String, key: String = "result") {
    findNavController().previousBackStackEntry?.savedStateHandle?.set(key, result)
}