```suspend fun loadData(id: Long) = flow { fet...

# coroutines

[Dmitry Khasanov]

suspend fun loadData(id: Long) = flow {
    fetchData(id) <-- now this is blocking function, how can I launch it in non blocking mode?
    roomDao.select(id)
        .collect {
            emit(result)
        }
}.flowOn(<http://Dispatchers.IO|Dispatchers.IO>)

suspend fun fetchData(id) {
    // make http request here and put data into database
}

Hi all. How can I launch fetchData function in parallel from flow {} ?

[streetsofboston]

You could do launch { fetchData(id) }

[streetsofboston]

Is fetchData blocking or suspending?

[streetsofboston]

(still, wrapping it in a launch would work, but if it is truly blocking, do launch(<http://Dispatchers.IO|Dispatchers.IO>) { fetchData(id) } instead)

[Dmitry Khasanov]

unfortunately there is no launch function inside flow builder

[streetsofboston]

Wrap the whole body of the flow in coroutineScope

suspend fun loadData(id: Long) = flow {
    coroutineScope {
        launch { fetchData(id) }
        roomDao.select(id)
            .collect {
                emit(result)
            }
    }
}.flowOn(<http://Dispatchers.IO|Dispatchers.IO>)

[Dmitry Khasanov]

looks like it is exactly what I need! Thanks a lot!

[streetsofboston]

Note that, in order to have fetchData to run in parallel with roomDao.select..., you must wrap then entire contents of the `flow`’s code inside coroutineScope. This is because coroutineScope suspends until all its children have finished, which would include the launch { fetchData(id) }. Then to keep things in parallel, the roomDao.select... need to be one of the `coroutineScope`’s children as well.

[Dmitry Khasanov]

thank you for explanation, Anton!