Hey guys, I am using LiveData coroutines KTX exten...

# android-architecture

[Hitanshu Dhawan]

Hey guys, I am using LiveData coroutines KTX extension for my project.
https://developer.android.com/topic/libraries/architecture/coroutines#livedata

The code is something like this.
ViewModel/Repository

fun getData() = liveData {
    val a = getFromDB()
    emit(a)
    val b = getFromNetwork()
    emit(b)
}

View

viewModel.getData().observe(this, Observer{
    // do ui stuff
})

This works perfectly fine. But the problem is now I want to add Swipe to Refresh feature, and want that the entire liveData {} block to run again.
How do I trigger a refresh call to the getData() LiveData?

One solution which is mentioned here (https://stackoverflow.com/a/58689791) is to introduce another MediatorLiveData and remove and re-add the liveData {} block on refresh. But I don't want to add 2 LiveDatas and it also seems like a hack.

Any good and elegant solution for this guys? Thanks.

[voben]

In viewmodel

val myLiveData = MutableLiveData() // This is a class property in your viewmodel

fun doFetch() {
 val a = getFromDB()
 myLiveData.value = a
 val b = getFromNetwork()
 myLiveData.value = b
}

and in your View class

viewModel.myLiveData.observe(this, Observer{
    // do ui stuff
})

// Calling `doFetch()` will redo the operation and set the livedata values

As an improvement, consider also exposing myLiveData to the view as an immutable livedata

[Hitanshu Dhawan]

Thanks @voben for the reply.
Yes, this method works perfectly. But I was looking something with the liveData {} block, which supports coroutines.
Is it possible to use the liveData {} block with refresh functionality? Or should I not use liveData {} block?
I'm little bit confused 🤔

[voben]

The Livedata builder is cold and only emits when the user starts observing it. So the only way to emit again would be by detaching and reattaching the observer or by attaching a new one

https://developer.android.com/topic/libraries/architecture/coroutines#livedata