Hello all, seeing what I think might be a bug w/ c...

# compose

[Billy Newman]

Hello all, seeing what I think might be a bug w/ compose navigation using a startDestination with a nullable default parameter. If my NavHost is using a route with a nullable default parameter it seems the navigation lib cannot find the route.

navigation destination home?foo=bar is not a direct child of this NavGraph

Code in reply

[Billy Newman]

NavHost(
            navController = navController,
            startDestination = "home"
         ) {
            composable(
              route = "home?foo={bar}",
              arguments = listOf(navArgument("foo") { defaultValue = ""; })
            ) { backstackEntry ->

versions:

navigation-compose:2.4.2
compose-version:1.2.0-beta03

[Billy Newman]

I have tried different combinations of nav argument with defaultValue, and nullable. Also tried to pass a dummy arg in the startDestination route. Is this a bug or am I doing something wrong?

[Billy Newman]

Should note, searched through issue tracker, didn’t find anything.

[Ian Lake]

Use `defaultValue`: https://kotlinlang.slack.com/archives/CJLTWPH7S/p1623851605280400?thread_ts=1623841420.270700&cid=CJLTWPH7S

[Billy Newman]

Ah, arguments is the issue. Thank you!

[Billy Newman]

Ian, any idea if this has been discussed as a future enhancement. Things start to get messy quickly when using string constants for route values. Sure you can add “{userId}” to the route constant. However you still run into issues when trying to navigate to a route with a non default parameter if using the sting constant. In the case of using arguments, perhaps the startDestination could match on the everything but the args. I am sure there is a lot more at play, just a thought

[Ian Lake]

If this is anything to do with your previous thread and how you are trying to build dynamic destinations, then you're just misusing arguments entirely 🙂

[Ian Lake]

The start destination of your graph should just be home because your route for your screen should be home - arguments shouldn't be a part of it at all

[Ian Lake]

I commented back on your other thread with what I was suggesting

[Billy Newman]

Ugh, sorry Ian, that makes sense. Home will not be my app entry point, it is temporarily as I build out the app.