Is there a way to implement a sort of recursive navigation route with compose navigation? In this a...

# compose

[Tim Malseed]

Is there a way to implement a sort of recursive navigation route with compose navigation?

In this app, you can navigate to, e.g. topics/topic1, or topics/topic1/topics/topic2 . The depth of recursion is undefined.. I’m not sure how to implement this, as implementing a composable for each possible level, e.g. composable(topic/{topicId}/subTopic{subTopicId}/moreSubtopic/{moreSubTopicId} doesn’t seem practical

[Ian Lake]

Is it important that the entire hierarchy is part of the route? Is topic/{topicId} different semantically from topic/{subTopicId}?

[Tim Malseed]

There’s no difference, but the hierarchy is structured.. So you should be able to navigate back through previous destinations (ideally)

[Ian Lake]

The structure of the route string has no impact on whether you can go back to previous destinations

[Tim Malseed]

Oh, I assumed the route and its arguments might be used to rebuild the stack after process death

[Ian Lake]

The NavController is responsible for maintaining the back stack; it already saves and restores that stack for you

[Tim Malseed]

My initial attempt naively just used the route myscreen/topics/{topicId}. Each time you want to navigate a level deeper, it calls navController.navigate("myscreen/topics/${topic.id}

But, when I attempt to retrieve the topicId from the NavBackStackEntry, once I’m more than one level deep, I seem to get a stale one. Which is what made me think this approach was incorrect.

[Ian Lake]

As long as you are getting the argument out of the NavBackStackEntry that is explicitly passed to your composable lambda, you'll get the exact set of arguments you passed into it

[Ian Lake]

(you would not want to use navController.currentBackStackEntry, etc.)

[Ian Lake]

Note that both destinations will exist simultaneously while you are animating to the new destination, so make sure it isn't just your logging that is confusing you

[Tim Malseed]

Oh, that definitely could be my problem!