Pass data back to previous fragment using Android Navigation

Question

I\'ve started using Android Architecture Components (Navigation and Safe Args, View Models) along with Koin library.

Currently, I\'ve got a problem with passing argu

Answer 1

Currently, I've got a problem with passing arguments between two fragments - I need to pass a string value from fragment A to fragment B, modify this value in fragment B and pass it back to fragment A.

The theoretical solution really is to have the two fragments in a shared tag, then scope the ViewModel to the ID of the navigation tag, this way you now share the ViewModel between the two screens.

To make this reliable, it's best to use the NavBackStackEntry of the Navigation tag as both a ViewModelStoreOwner and SavedStateRegistryOwner, and create an AbstractSavedStateViewModelFactory that will create the ViewModel using the ViewModelProvider, while also giving you a SavedStateHandle.

You can communicate the results from FragmentB to FragmentA using this SavedStateHandle, associated with the shared ViewModel (scoped to the shared NavGraph).