Let’s say I have an Android `DialogFragment` that uses a `ViewModel` with `viewModelScope` support. ...

# android

[Martin Nordholts]

Let’s say I have an Android DialogFragment that uses a ViewModel with viewModelScope support. In the UI, the user fills in a bunch of data and the click a Submit button which closes the dialog and does a HTTP POST of the data. Let’s say I use Retrofit2 with suspend support.

I should clearly not use viewModelScope.launch to do the HTTP POST because it will be cancelled when the UI is closed.

Naive as am, I think it would be fine to use GlobalScope.launch in this case to do the HTTP POST, since I under no circumstances want that HTTP POST to be cancelled.

Would this be bad style? If yes, what scope should I use instead? Some CoroutineScope field in my Android Application class perhaps? Let’s ignore edge cases like network failure for now.

[Dominaezzz]

under no circumstances want that HTTP POST to be cancelled.

GlobalScope it is. Since something like that literally can't be scoped.

[Dominaezzz]

I think there's too much hesitation around GlobalScope. So much so, that sometimes I see code like CoroutineScope(Dispatchers.Main).launch {} (which is worse that GlobalScope) just so GlobalScope isn't directly used.

[Matej Drobnič]

under no circumstances

Be careful to not assume this. Request can be cancelled even if your code is perfect. App can crash, phone can run out of battery, wifi router can go down etc.

[Martin Nordholts]

That is a fair point, although with ‘cancel’ I was in this particular case referring to cancel as in Job.cancel(). Sorry for being unclear. App crashes and battery depletion are of course always a possibility.

[Martin Nordholts]

I think there’s too much hesitation around GlobalScope.

Sorry for reviving an old thread but I think this is important to discuss. It is not strange that there is hesitation around this since Roman himself says so here: https://medium.com/@elizarov/the-reason-to-avoid-globalscope-835337445abc

[Daniel]

Why not use work manager?