Hey guys, Do you have any good example of <Kotlin: Sealed Classes for better handling of API Respons...

# multiplatform

[Vivek Modi]

Hey guys, Do you have any good example of Kotlin: Sealed Classes for better handling of API Response in multiplatform?

[Tim Oltjenbruns]

sealed class ApiResult<out R, out E>
data class ApiSuccess<out R>(val value: R) : ApiResult<R, Nothing>()
data class ApiFailure<out E>(
    val status: ApiErrorStatus,
    val details: E?
) : ApiResult<Nothing, E>()

This is ours. It helps when you have domain specific error response bodies in addition to success bodies.

[Tim Oltjenbruns]

For example, we have an api that changes an order state. It requires the clients expected state as well as the new state to catch concurrency errors. The details of what the actual state was when it doesn’t match the expected state comes back in a domain specific error body.

[Tim Oltjenbruns]

Notably we don’t have a loading state, because that’s more of a View/Presenter layer concern, and these objects are just used in the repository/data layer.

[mike.holler]

Why does the original approach not work for KMP?

[Tim Oltjenbruns]

How does it not work for KMP?

[mike.holler]

The OP was asking for good examples of using sealed classes in multiplatform. The article linked seems like it would work with multiplatform as-is. I was confused about the basis of the question.

[Tim Oltjenbruns]

Oh for sure, I missed that myself. It seems like it would in fact work

[Tim Oltjenbruns]

So @Vivek Modi why doesn’t it work? Or more precisely, how doesn’t it work?

[Vivek Modi]

Hey @Tim Oltjenbruns great explanation. As you see in the link, there is function called fetchResult inside that code is checking every time response.code() and route according to domain specific Success or Error body. Is there any better way it will automatically route on specific domain rather than checking every time.

[Tim Oltjenbruns]

Well that’s dependent on what you use to make HTTP calls

[Tim Oltjenbruns]

The example you linked looks like it uses Retrofit?

[Vivek Modi]

@Tim Oltjenbruns @mike.holler I am using Ktor for api call.

[Tim Oltjenbruns]

So the implementation will be different then.

[Vivek Modi]

So do you have any sample project?

[Tim Oltjenbruns]

I do not have an example using Ktor. For my KMP I use Retrofit on Android and another library for iOS

[Tim Oltjenbruns]

You may want to ask in the Ktor channel

[mike.holler]

#ktor

[Vivek Modi]

ok sure thanks