listenerMiddleware type error in matcher using custom actions.

[antondalgren]

I have a codebase using legacy redux patterns and trying to slowly but steadily transition to using modern redux. I have a set of old Actions that are created similiar to ExtraAction mentioned below. When using the listenerMiddleware to add a set of type guards as matchers using the isAnyOf utility as demonstrated below, I see a type error on the matcher.

Also, it seems as the type inferred from the predicate (probably the matcher to) doesn't carry along into effect callback.

    interface ExtraAction extends Action {
      payload: number
    }

    function isPayloadAction(action: any): action is ExtraAction {
      return (
        isFluxStandardAction(action) && typeof action.payload === 'number'
      )
    }

    startListening({
      matcher: isAnyOf(isPayloadAction),
      effect: (action, listenerApi) => {
        expectTypeOf(action).toMatchTypeOf<ExtraAction>()
      },
    })

[EskiMojo14]

predicate isn't used as a type guard, only matcher is.

Could you post what the type error you're getting is?

#3862 is also likely related.

[antondalgren]

predicate isn't used as a type guard, only matcher is.

Could you post what the type error you're getting is?

#3862 is also likely related.

Thank you for the swift response.

Here is the ts-error:

No overload matches this call.
  The last overload gave the following error.
    Type '(action: any) => action is ActionMatchingAnyOf<[(action: any) => action is ExtraAction]>' is not assignable to type 'undefined'.ts(2769)
types.ts(489, 7): The expected type comes from property 'matcher' which is declared here on type '{ actionCreator?: undefined; type?: undefined; matcher?: undefined; predicate: AnyListenerPredicate<unknown>; effect: ListenerEffect<UnknownAction, unknown, ThunkDispatch<unknown, unknown, UnknownAction>, unknown>; }'
types.ts(485, 3): The last overload is declared here.

This does provide action with the correct type, thus using a type guard as predicate should carry along the correct type, shouldn't it? 🤔

    startListening({
      predicate: incrementByAmount.match,
      effect: (action, listenerApi) => {
        expectTypeOf(action).toMatchTypeOf<ExtraAction>()
      },
    })

[markerikson]

No, predicate explicitly does not narrow the action type. It's a very generic (action, prevState, nextState) => boolean callback that could have any logic inside, and so it can't guarantee the type of action.