Hi guys. What is the difference between liveData {...

# android

[gabin]

Hi guys. What is the difference between liveData {} and viewModelScope {} builders in ViewModel? Does liveData survive activity recreation?

[satyan]

If by activity re-creation you mean when an activity is recreated after a process death, no.
However, if you mean configuration change (rotation, resize, etc), yes.

I've never seen viewModelScope{} but livedata{} is used to create a Livedata using the ViewModel coroutine scope. (Using emit to emit values or emitSource to emit values from another Livedata)

The viewmodelScope is a CoroutineScope scoped by the ViewModel lifecycle.

[gabin]

Yep, I mean exactly configuration change. I know that viewModelScope{} survives it, but I am not sure about livedata{} . Lets say I made a network request inside livedata{} and rotated screen couple of times - will the result arrive to observer ? Will it be cancelled if viewModel is destroyed and I moved to another activity?

[satyan]

The ViewModel itself survive configuration change. So with livedata you'll expose a Livedata and when the activity state will be started it's going to observe the value of the Livedata.

[Adam Powell]

The block for liveData {} will stay alive for as long as the resulting LiveData has active observers, plus a configurable timeout. The default is non-zero and you can change it with a parameter to the liveData {} builder. Therefore if you start re-observing the same LiveData instance after a config change before the timeout expires, yes, the work happening in that block will continue.

[satyan]

I wasn't aware of the timeout 👍
Thank you for the clarification 🙂