NavArgsReflectionLazy.kt

// Can be used as generic method to retrieve NavArgs? in the BaseViewModel
// usage val viewModel by navArgsReflection()

class NavArgsReflectionLazy<Args : NavArgs?>(
    private val navArgsClass: KClass<out Fragment>,
    private val arguments: () -> Bundle?
) :
    ReadOnlyProperty<Any?, Args?> {

    private var navArgs: NavArgsLazy<*>? = null

    override fun getValue(thisRef: Any?, property: KProperty<*>): Args? {
        if (navArgs == null) {
            val localArguments = arguments.invoke() ?: return null


            val className = "${navArgsClass.java.canonicalName}Args"

            // Let's check if Args class actually exists
            val navArgsClass = requireNotNull(getArgNavClass(className)) {
                "Arguments where passed to a fragment, but corresponding argument class $className does not exist. Arguments: $arguments"
            }

            navArgs = NavArgsLazy(navArgsClass) { localArguments }
        }

        @Suppress("UNCHECKED_CAST")
        return navArgs?.value as Args
    }

    private fun getArgNavClass(className: String): KClass<NavArgs>? = try {
        @Suppress("UNCHECKED_CAST")
        Class.forName(className).kotlin as KClass<NavArgs>
    } catch (e: ClassNotFoundException) {
        null
    }
}

@MainThread
fun Fragment.navArgsReflection() = NavArgsReflectionLazy<NavArgs>(this::class) { arguments }