Send action back into the system when effect is canceled

[vykut]

Hi,

In my scenario I have a long running effect that makes some requests to the local database as well as a network API in order to fetch some data.
Because this effect emits from time to time via send(.delegate(.searchResults(...))), I store a boolean in the State e.g isSearching.
In case the effect gets canceled I would like to be able to flip the isSearching boolean back to false, but the send callback stops working once the task has been canceled.

Any ideas how I can/ should model my logic?

[vykut]

Hi @mbrandonw and @stephencelis, I would greatly appreciate your inputs on this 🙏

[mbrandonw]

You can use .concatenate to send an action when an effect completes or is cancelled:

return .concatenate(
  .run { send in 
    …
  }
  .cancellable(id: …),

  .send(.searchFinished)
)

[vykut]

I just stumbled upon withTaskCancellation and I see it provides similar functionality.
Refactoring your example to use withTaskCancellation, yields the same results, unless I'm missing something...

return .run { send in
    await send(.searchStarted)
    try? await withTaskCancellation(id: CancelID.search, cancelInFlight: true) {
        try await self.clock.sleep(for: .milliseconds(300))
        // network request
        await send(.delegate(.result(...)))
        // other network request
        await send(.delegate(.result(...)))
    }
    await send(.searchFinished)
}

[mbrandonw]

Hi @vykut yeah that will work too.