CODEWITHSUNDEEP
androidandroid-asynctaskreactive-programmingrx-java2rx-android
Rana.S
Rana.S

Reputation: 2275

RxJava Chain requests & update to Observer from any request

I have 3 API requests which i am handling with RxJava Chaining (Using FlatMap).
For Example : A , B , C

Request A is giving HttCode Error 400. So i want data of its response body to show error message in UI. I handled it in onError() method & parse body data. But don't know how to send it to Observer without stoping chain. If i am using . Observer.just(ErrorData). It is throwing it into next Request B FlatMap.

Request B & C are dependent on each other. Request B execute after A. I don't want to stop their execution if there is error in Request A.

So i need Request A Error data & Request C Success data in Observer to show Error message & Success data respectively.

Can anybody suggest any idea to solve it ?

Upvotes: 0

Views: 220

Answers (1)

Ramees Thattarath
Ramees Thattarath

Reputation: 1093

You can achieve this by Mapping Observable types to monad type. ie, Map the Observables to a type that can hold both error and success states, if an error is thrown in observable stream A, error type is propogated using onErrorResumeNext.

Map observables B and C such that it can hold the error message from A. while flat mapping A with B, check the type of the value emitted from A and if the value is error type propogate the error message into C as well

Here is an example I tried in kotlin

 val obs1 = Observable.create<Float> {
        throw IllegalStateException("Shit happens")
    }
    val obs2 = Observable.just(1)
    val obs3 = Observable.just("hii")

    obs1.map { Result(null, it) }.onErrorResumeNext { er: Throwable ->
        Observable.just(Result<Float>(er.message, null))
    }.flatMap { fltResult ->
        obs2.map { Result(fltResult.error, it) }
    }.flatMap { intResult ->
        obs3.map { Result(intResult.error, it) }
    }.subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread()).subscribe({
            Log.d("Data: Error", it.data + ": " + it.error)
        }, {
            Log.d("Error", it.message)
        })

Result class being

data class Result<T>(val error : String?,val data : T?)

Upvotes: 1

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