fix(store): replace Creator with ActionCreator on createAction

[meeroslav]

createAction returns incorrect type as neither Creator not it's return type contains type.
The proper return type is ActionCreator with the inner typed creator

Closes meeroslav/ng-helpers#2

Could contribute to #2192 as well.

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PR Type

What kind of change does this PR introduce?

[X] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
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[ ] Other... Please describe:

What is the current behavior?

Using type ActionCreator as the input parameter is causing type errors due to the Creator type being insufficient. ActionCreator is a function that has type defined and returns typed Action. Creator does not return typed Action.

Closes meeroslav/ng-helpers#2

What is the new behavior?

ActionCreator now returns TypedCreator that extends CreatorFunctionality by returning TypedAction

Does this PR introduce a breaking change?

[ ] Yes
[X] No

Other information

[ngrxbot]

Preview docs changes for e846375 at https://previews.ngrx.io/pr2299-e846375/

[meeroslav]

Thanks, @alex-okrushko, for quick feedback. I should have provided a bit more information to clarify the reasoning.

PR solves two complementary type issues.

createAction should return ActionCreator<T>

Since none of the overrides return Creator this is the correct return type. Equally, defineType should return ActionCreator<T> not Creator. This was just a side effect of the actual problem:

ActionCreator<T> is a function that returns TypedAction<T>

This is where the error actually happens. If I write a function like this:

function actionWrapper<P>(creator: ActionCreator<string, Creator>, payload: P): Observable<Action> {
  return of(creator(payload));
}

It will report error Type 'Observable<{}>' is not assignable to type 'Observable<Action> | ((...args: any[]) => Observable<Action>)'.

If you look closely at ActionCreator type, it extends Creator with type property. Since, as you mentioned, type property is explicitly forbidden on Creators return type R, ActionCreator could never return an object with type property - therefore, the result of ActionCreator type could never be Action type as type property would be missing.

The second generic type of ActionCreator cannot be Creator as it's in contradiction with createAction return types () => TypedAction<T>, (props: P) => P & TypedAction<T>> and FunctionWithParametersType<P, R & TypedAction<T>>.

I agree that TypedCreator might be an unfortunate naming choice. Perhaps it should be explicitly typed as FunctionWithParametersType<P, R & TypedAction<T>>.

[meeroslav]

@alex-okrushko, I've seen now that your PR #2301 solves the second issue so I will revert TypedCreator

[alex-okrushko]

@meeroslav Yes, thanks. There was a separate issue that got me to rework that part.

I think "createAction should return ActionCreator" is the only part that should be adjusted. Thanks for creating this issue and PR.

[meeroslav]

@alex-okrushko, are the latest changes (reverts) then ok, or should I do something additional in this PR?

[alex-okrushko]

I think this is good!