Android RxJava2-引發錯誤時如何進行api調用？

Question

因此，我目前正在使用flatMap將API調用鏈接在一起，並且在我的用例中效果很好。 如果我的一個呼叫返回失敗的響應代碼，那么我將傳遞一個錯誤單，其中包含一個throwable，並帶有一條消息，指出哪個呼叫失敗並且一直持續。 這是我現在的做法：

dataManager.apiCall1(dataManager.sessionId!!)
        .subscribeOn(schedulerProvider.io())
        .observeOn(schedulerProvider.ui())
        .flatMap{apiCall1Response ->
            if (apiCall1Response.isSuccessful && apiCall1Response.body() != null) {
                // First api call was successful, execute api call 2.
                return@flatMap dataManager.apiCall2(apiCall1Response.importantVal)
            } else {
                // First api call failed 
                return@flatMap Single.error<Throwable>(Throwable("First api call failed."))
            }
        }.flatMap{apiCall2Response ->
            if (apiCall2Response != null && apiCall2Response.isSuccessful && apiCall2Response.body() != null) {
                // Second api call was successful, execute api call 3.
                return@flatMap dataManager.apiCall3(apiCall2Response.importantVal)
            } else if (apiCall2Response is Throwable) {
                // Api Call 1 Failed.
                return@flatMap Single.error<Throwable>(apiCall2Response)
            } else {
                // Second api call failed
                return@flatMap Single.error<Throwable>(Throwable("Second api call failed."))
            }
        }.subscribe({apiCall3Response ->
            if (apiCall3Response is Response<*> && apiCall3Response.body() != null) {
               // Success!
               navigator?.successful(response)
            } else if (apiCall3Response is Throwable) {
               // Something failed from before.
               navigator?.handleError(apiCall3Response)
            } else {
               // Third api call failed, handle error
               navigator!!.handleError(Throwable("Api call 3 failed."))
            }
        }, {throwable ->
            navigator!!.handleError(throwable)
        })

好吧，現在我意識到，如果我的第一個api調用成功並且其他任何調用都失敗，則需要進行其他api調用。 這是登錄用戶的一系列調用，如果登錄調用成功，但是下一次調用失敗，則需要調用api注銷端點。 我知道在subscribe（）方法中創建另一個單一的方法是不好的做法，所以我不想這樣做。 我寧願通過注銷調用，但問題是由於注銷和apiCall3都返回空主體，因此無法知道在subscribe方法中返回哪個api調用。 如果apiCall3失敗，我也想調用注銷端點，但是不確定是否可以。 這是我正在嘗試做的事情：

dataManager.apiCall1(dataManager.sessionId!!)
        .subscribeOn(schedulerProvider.io())
        .observeOn(schedulerProvider.ui())
        .flatMap{apiCall1Response ->
            if (apiCall1Response.isSuccessful && apiCall1Response.body() != null) {
                // First api call was successful, execute api call 2.
                return@flatMap dataManager.apiCall2(apiCall1Response.importantVal)
            } else {
                // First api call failed 
                return@flatMap Single.error<Throwable>(Throwable("First api call failed."))
            }
        }.flatMap{apiCall2Response ->
            if (apiCall2Response != null && apiCall2Response.isSuccessful && apiCall2Response.body() != null) {
                // Second api call was successful, execute api call 3.
                return@flatMap dataManager.apiCall3(apiCall2Response.importantVal)
            } else if (apiCall2Response is Throwable) {
                // Api Call 1 Failed.
                return@flatMap Single.error<Throwable>(apiCall2Response)
            } else {
                // Second api call failed, logout
                return@flatMap dataManager.logoutApiCall()
            }
        }.subscribe({apiCall3OrLogoutResponse ->
            // I would like to be able to determine which call this response is from. That is the question. 
            if (apiCall3OrLogoutResponse is Response<*> && apiCall3OrLogoutResponse.body() != null) {
               // Success!
               navigator?.successful(response)
            } else if (apiCall3OrLogoutResponse is Throwable) {
               // Something failed from before.
               navigator?.handleError(apiCall3OrLogoutResponse)
            } else {
               // Third api call or logout call failed, handle error
               if (apiCall3OrLogoutResponse is ApiCall3) {
                  // Api Call 3 failed. 
                  // Somehow call logout api endpoint
               } else if (apiCall3OrLogoutResponse is LogoutCall {
                  // Logout call failed.
                  navigator?.handleError(Throwable("Logout failed."))  
               }       
            }
        }, {throwable ->
            navigator!!.handleError(throwable)
        })

有一個更好的方法嗎？ 我的用例是進行三個連續的api調用，如果第一個失敗，則將一個throwable發送給訂閱者，如果第一個成功，然后失敗，則進行另一個api調用。

Answer 1

我通過拋出自定義異常而不是向下傳遞Single.error並在flatMapCompletable中而不是在訂閱中檢查了我的最終調用來解決了這一問題。 然后，如果異常不是登錄異常，則在doOnError中調用注銷端點。

dataManager.apiCall1(dataManager.sessionId!!)
    .subscribeOn(schedulerProvider.io())
    .observeOn(schedulerProvider.ui())
    .flatMap{apiCall1Response ->
        if (apiCall1Response.isSuccessful && apiCall1Response.body() != null) {
            // First api call was successful, execute api call 2.
            return@flatMap dataManager.apiCall2(apiCall1Response.importantVal)
        } else {
            // First api call failed 
            throw ApiCall1Exception("Api Call 1 failed.")
        }
    }.flatMap{apiCall2Response ->
        if (apiCall2Response != null && apiCall2Response.isSuccessful && apiCall2Response.body() != null) {
            // Second api call was successful, execute api call 3.
            return@flatMap dataManager.apiCall3(apiCall2Response.importantVal)
        } else {
            // Second api call failed
            throw Throwable("Api call 2 failed.")
        }
    }.flatMapCompletable{apiCall3Response ->
        if (apiCall3Response.body() != null) {
            // All api calls were successful!
            Completable.complete()
        } else {
            // Third api call failed.
            throw Throwable("Api call 3 failed.")
        }    
    }.doOnError{throwable ->
        if (throwable !is ApiCall1Exception) {
            // Api call 1 was successful, but something else failed, call logout endpoint.
            dataManager.logout()
                  .subscribeOn(schedulerProvider.io())
                  .observeOn(schedulerProvider.ui())
        }
    }.subscribe({
        // Success!
        navigator?.success()
    }, {throwable ->
        // Something failed!
        navigator?.handleError(throwable)
    })