Network Middleware fragment for Unidirectional Flow post.

network_middleware.kt

// This middleware executes the async requests related with the Rest API

internal val networkMiddleware: Middleware<AppState> = { dispatch, state ->
    { next ->
        { action ->
            when (action) {
                // an async operation is called
                is SetDeviceInfo -> { getDeviceDescription(deviceId = action.deviceId,
                                                           deviceInfo = action.payload,
                                                           dispatch = dispatch) }
                // ... more action catches
            }
            // the orginal action continues on its way to other middlewares
            // until reach the reducers.
            next(action)
        }
    }
}

private fun getDeviceDescription(deviceId: DeviceId, deviceInfo: Result<DeviceInfo, Throwable>, dispatch: DispatchFunction) {
    val appStoreClient = DeviceManagerApplication.appStoreClient ?: return

    deviceInfo.map { info ->
        val cin = Hex.encodeHex(info.deviceId.cin)
        val batchId = info.batch.batchId
        // Rx async operation is called            
        appStoreClient.getDeviceDescription(cin, batchId, null)
                .compose(asRemoteRequest())
                // once the result arrives, a new action is dispatched,
                // passing through all middlewares again and finally reaching the reducers.
                .subscribe ({ dispatch.invoke(SetDeviceDescription(deviceId, NetworkResult.ok(it.description))) },
                            { dispatch.invoke(SetDeviceDescription(deviceId, NetworkResult.err(it))) })
    }
}