I have an app which fetches a list of posts from an API. The app uses <Decompose> for navigation. I'...

# compose-desktop

[Ali Albaali]

I have an app which fetches a list of posts from an API. The app uses Decompose for navigation. I'm wondering what's the best way to persist the list so the list is still available even after navigating to a different destination.

Should I save it using rememberSaveable() , Decompose's InstantKeeper or StateKeeper, or an embedded SQLite database, thoughts?

[Arkadii Ivanov]

Is it for desktop only?

[Ali Albaali]

For now, yes.

[Arkadii Ivanov]

So if it's desktop only, then you can just keep a reference to the list in the screen's component. Usually there should be something like MutableState<List<Item>> or similar. Then when you push/pop screens, the previous screen`s component will not be destroyed.

[Ali Albaali]

I have this in the screen and it's loading each time. Am I missing something?

val state by produceState<List<Item>>(emptyList()) {
    fetchItems().collect { value = it }
}

[Arkadii Ivanov]

This code seems unrelated to Decompose. Would be good to see more code. When using Decompose, each screen is usually represented as a class.

[Ali Albaali]

I'm using the code from this article. I have a sealed interface Screen and all of the screens inherit from it.

[Arkadii Ivanov]

Right. The article is quite outdated already, I should update it with this information. Basically when another screen is pushed to the stack, the previous Composable leaves the composition. All remembered state is lost. You can try using rememberSaveable, it should help. But personally I recommend using classes. This may look like more boilerplate, but it also gives more power. Here is the tutorial: https://github.com/JetBrains/compose-jb/tree/master/tutorials/Navigation#managing-navigation-outside-composable-world

[Ali Albaali]

You mean something like ViewModel on Android which survives composition?

[Arkadii Ivanov]

It would be more comparable to android fragments, but with simpler lifecycle and much less APIs

[Ali Albaali]

In the tutorial you have mentioned, I'm using the second approach "Managing navigation inside @Composable world", are you implying I should change it to the first one?

[Arkadii Ivanov]

The second approach is valid, but it has the side effect you are experiencing. So rememberSaveable should help in your case. But it will stop working if you add Android in the future. To keep this approach working with Android, you will need to make items Parcelable.

[Ali Albaali]

Ah I see. Thank you a lot, I really appreciate it :)