Hi, I'm trying to pass a variable out of my LaunchedEffect so I can use it. I'm not sure how to acco...

# compose

[Nat Strangerweather]

Hi, I'm trying to pass a variable out of my LaunchedEffect so I can use it. I'm not sure how to accomplish that. Any ideas?

[Nat Strangerweather]

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

[Nat Strangerweather]

The problem is getting retrofitData

[Zach Klippenstein (he/him) [MOD]]

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")
}

[Nat Strangerweather]

Brilliant, thank you so much!

[Adam Powell]

you'll want a value = in there but otherwise yes 🙂

[Zach Klippenstein (he/him) [MOD]]

Oops yea, I always forget about that

[Colton Idle]

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]

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]

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

[Nat Strangerweather]

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

[Nat Strangerweather]

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