Is it possible to define something similar to Retrofit CallAdapter.Factory to define custom return t...

# ktor

[Matija Sokol]

Is it possible to define something similar to Retrofit CallAdapter.Factory to define custom return types using Ktor client on Android? I want to define my return type using Arrow's Either<Left, Right>

[Aleksei Tirman [JB]]

Can you please share an example to illustrate the question?

[Matija Sokol]

Sure.

For simplicity lets define our model like this (probably same approach will be also with Either):

sealed class Result<out T> {
  data class Success<out T>(val data: T) : Result<T>()
  data class Error(val error: ErrorEntity) : Result<Nothing>()
}

And what I want is to return Result type when calling HttpClient methods:

suspend fun fetchData(): Result<String> = httpClient.get(url).body()

What I found is that maybe I can do this by creating plugin but I'm not sure if I'm on the right track:

val ConverterPlugin = createClientPlugin("ConverterPlugin", ::ConverterPluginConfig) {
  transformResponseBody { response, content, requestedType ->
  }
}

[Aleksei Tirman [JB]]

I don't think it's possible to do via the plugin. You'd need to write wrappers for each request method.

[Matija Sokol]

Something like this?

suspend fun fetchData(): Result<String> = try {
  Result.success(httpClient.get(url).body())
} catch (t: Throwable) {
  Result.failure(t)
}

[MV]

runCatching?

[Matija Sokol]

It would also works with runCatching. Actually, I would prefer runCatching if Kotlin Result type is used, but for custom models I would go with try-catch.