Exposing suspend function vs exposing flow

Question

In android development, we can expose Kotlin flow or suspend function if we are using Kotlin coroutines. I see in many project that flow is exposed even if the network request is one shot. After that, they use stateIn in viewModels to create StateFlow. What I am wondering is that is there any advantage of exposing flow instead of suspend function even though it is one shot request ? All I can think that flow has intermediate operators which might help.

Answer 1

This is a bit opinion-based, but for me personally using a flow for a single item is an anti-pattern. This is similar to always returning a one-sized list of strings instead of a string directly. It is not that bad for the performance or ease of use, but it may be confusing, because the caller may expect multiple items, they may not be sure if the flow is finite or it runs forever, etc. Behavior of a suspend function is very clear and explicit.

Of course, there are good reasons to use such single-item flows, e.g. if we plan to extend it in the future. However, as a rule of thumb, I would avoid doing this.

Having said that, it is pretty easy to convert from one to another. We can convert a flow to suspend by: flow.first(). And we can do the other way around by: flow { foo() } or ::foo.asFlow().