I use Channels to send one off events from my ViewModel to m

Question

I use Channels to send one off events from my ViewModel to my fragment What should I use for events that should only be received once at most ConflatedChannel for some reason still allows multiple events to be sent Right now I have this `receive` suspends till an event is sent over the channel but the return type is `Unit` so I ignore the return value

gildor · Answer

Why for some reason Conflated channel is essentially observable state which doesn t complete until it closed Instead of channel I would use suspend function which under the hood could use CompletableDeffered it s the easiest way to have a single value which is suspended until deferred is completed

Florian · Answer

is this suited to communicate from the ViewModel to the Fragment

Florian · Answer

right now I use normal Channel + `receiveAsFlow` and then for events that are only supposed to happen once I use `take 1 ` just to make sure What do you think about that

gildor · Answer

Yes nothing special in communication between view model and a fragment

Florian · Answer

Well the special part is that the ViewModel doesn t have a reference to the Fragment

gildor · Answer

You can use flow but if you just need some lazy way to populate a single value you may use CompletableDeffered Also you really don t need channel you can use State flow directly

Florian · Answer

afaik StateFlow gets collected again on an orientation change

Florian · Answer

which I don t want for 1 time events

gildor · Answer

State flow cannot be collected it s just an observable state it cached value it s not different in this case comparing to conflated channel

gildor · Answer

1 time event is better encode with suspend function imo

gildor · Answer

Maybe of you provide some example what you want achieve it would be easier to discuss

gildor · Answer

But what I see you just need a suspend function and I don t see any communication problem fragment has suspend function it doesn t need any reference to fragment fragment just call a function

Florian · Answer

I need it for events where the ViewModel decides when it s time to trigger it and then the fragment has to do something

Florian · Answer

Florian · Answer

this is my current approach

Florian · Answer

the corresponding Fragment is in the same package it s a very small project

gildor · Answer

A suspend function which suspend until the event is fine for this

gildor · Answer

Flow also fine for this

Florian · Answer

do you have an example of that suspend function approach

Florian · Answer

Do you mean I pass a suspend function block from my fragment to my ViewModel and then call invoke in the ViewModel

Florian · Answer

but wouldn t this create an implicit reference to the fragment inside the ViewModel