Hello all quite simple question I m experimenting a bit with

Question

Hello all quite simple question I m experimenting a bit with coroutines and I wonder what is the best approach to handle multiple endpoints inside single `UseCase` I guess `flow` should be used

streetsofboston · Answer

End points like network requests

antoniomarin · Answer

Yep I can do the same logic if I leave objects as Single s but I guess that not really coroutine way

streetsofboston · Answer

For Singles and Maybes just use `suspend fun `

antoniomarin · Answer

Yep but inside that one

streetsofboston · Answer

Not sure what you mean

streetsofboston · Answer

```class UseCase suspend fun getDataFromNetwork input Data Response val request1Result = repo getResult1 input field1 val request2Result = repo2 getResult2 input field2 return combineResults request1Result request2Result ```

antoniomarin · Answer

If request1 fails then I want to try out with result2 but both should be returning same value

streetsofboston · Answer

Based on your example could you post that later in this thread < antoniomarin> ```suspend fun buildUseCase params None CharSequence val clientId = sessionRepository getLoggedInClientId return try val content = contentsRepository getHtmlContent CONTENT NAME clientId content contentValue toHtml catch error Throwable contentsRepository getHtmlContent CONTENT NAME DEFAULT CLIENT ID ```

streetsofboston · Answer

And if you need to go from a `Single lt T gt ` to a `Flow lt T gt ` in case you can t change the function method signatures of your repos take a look at this <https github com Kotlin kotlinx coroutines tree master reactive kotlinx coroutines rx2>

antoniomarin · Answer

Hi < streetsofboston> this is my existing code ```override fun buildUseCase params None Single lt CharSequence gt return sessionRepository getLoggedInClientId flatMap clientId gt contentsRepository getHtmlContent CONTENT NAME clientId onErrorResumeNext contentsRepository getHtmlContent CONTENT NAME DEFAULT CLIENT ID ``` Thanks for helping one question tho how to handle error for second api which is in catch block Does that means I would need to add other `try` block inside existing one I m trying to figure out are there more elegant solutions smile

streetsofboston · Answer

The second call to `getHtmlContent` is part of the onErrorResumeNext If that second call emits an exception throwable the final Single returned by buildUseCase will emit that exception as well The same will happen in the `suspend fun buildUseCase` snippet as well If the second call to `getHtmlContext` throws an exception the `suspend fun buildUseCase` will throw an exception Your Rx example and the corresponding `suspend` example are behaving in similar ways

streetsofboston · Answer

You can wrap the calls inside a `runCatching` block followed by a ` mapCatching` block which allows you to avoid nested try catch clauses

antoniomarin · Answer

Uh haven t heard about those two gonna check them out btw can similar be achieved by `flow` going `flowOf api1 api2 ` and then doing some kind of reactive flow Sorry if I m making nonsenses smile

streetsofboston · Answer

Using flow is overkill for async functions that just emit at most one value In general you d consider Completable == gt suspend fun function Unit Maybe lt T gt == gt suspend fun function T Single lt T gt == gt suspend fun function T Observable lt T gt or Flowable lt T gt == gt Flow lt T gt

antoniomarin · Answer

I ended up using something similar if someones needs it ```try val result = runCatching repository api params1 getOrElse repository api params2 handleSuccess result catch exp Exception handleError exp ```