Hi I m trying to pass a variable out of my LaunchedEffect so kotlinlang #compose

@Composable
fun CallApi() {
    LaunchedEffect(key1 = {}, block = {
        val retrofitData = retrofitBuilder.getBooks("flower")
    })
    LazyColumn(content = {
        item {
            for (item in retrofitData.items) {
                Text(text = item.volumeInfo.title)
            }
        }
    })
}

The problem is getting retrofitData

Zach Klippenstein (he/him) [MOD]

12/13/2021, 10:51 PM

Use a

MutableState

, something like this:

var retrofitData by remember { mutableStateOf(emptyList()) }
LaunchedEffect(retrofit) {
  retrofitData = retrofit.getBooks("flower")
}
LazyColumn(…

Make sure to pass any dependencies used in your lambda as keys, in this case the retrofit object. This pattern is common enough that there’s a helper for it:

val retrofitData by produceState(initialValue = emptyList(), key1 = retrofit) {
  retrofit.getBooks("flower")
}

😊 1

Nat Strangerweather

12/13/2021, 10:57 PM

Brilliant, thank you so much!

Adam Powell

12/14/2021, 2:39 AM

you'll want a

value =

in there but otherwise yes 🙂

🙏 1

Zach Klippenstein (he/him) [MOD]

12/14/2021, 2:54 AM

Oops yea, I always forget about that

Colton Idle

12/14/2021, 5:32 PM

Most of this is going over my head (mostly due to me being unfamiliar/unsure of my own knowledge on LaunchedEffect) Nat, just out of curiosity, what are you accomplishing with your code snippet here? I'm intrigued 😄

Nat Strangerweather

12/14/2021, 8:30 PM

I'm retrieving book details from the Google Books api, ie a list of book titles that match the search term "flower", and displaying it in a LazyColumn. 😊

Colton Idle

12/14/2021, 8:37 PM

Why is this being done in a LaunchedEffect though? Wouldn't your ViewModel (or similar) be in charge of fetching?

Nat Strangerweather

12/14/2021, 8:42 PM

The interface that does the fetching is a suspend function...

Lol, I'm not an expert at all. I'm trying to work it out myself. 😉

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