Create a factory for actions using createAction not working

[ChakirMrabet]

I want to create a function that returns an action function using the createAction function:

function actionFactory<T extends object>(description: string) {
  return createAction(
    `[${FEATURE_STATE_NAME}] ${description}`,
    props<T>() as ActionCreatorProps<T> & NotAllowedCheck<T>
  );
}

I want to do this to simplify the creation of actions in my project.

I get the following error:

 error TS2344: Type 'T' does not satisfy the constraint 'NotAllowedInPropsCheck<T>'.
  Type 'object' is not assignable to type 'NotAllowedInPropsCheck<T>'.

18     props<**T**>() as ActionCreatorProps<T> & NotAllowedCheck<T>

Any ideas of what I'm doing wrong?

I'm using NgRx version 13.

Thanks.

[david-shortman]

T must be guaranteed to satisfy the constraint NotAllowedInPropsCheck. This type guard excludes objects with a type property, empty objects, and primitives.

I am not aware of a way to type this such that a generic declared in actionFactory is guaranteed to pass this check. It only works with concrete object types.

However, if you take in a "props config" as a parameter, then you could make a factory:

const FEATURE_STATE_NAME = 'Some Feature';

function actionFactory<D extends string, P extends object>(description: D, /* include this param 👉 */ config: ActionCreatorProps<P> & NotAllowedCheck<P>) {
  return createAction(`[${FEATURE_STATE_NAME}] ${description}`, config);
}

// 👇 then pass a props instance as an argument
const ExampleAction = actionFactory('Example Action', props<{ some: string }>());

// the action works as expected
const exampleInstance: { some: string; } & TypedAction<'[Some Feature] Example Action'> = ExampleAction({ some: 'value' });

[ChakirMrabet]

Thanks!! That's a clever way of doing it!

I've just had to refactor it a little bit to allow actions with no props:

function actionFactory<D extends string, P extends object>(
  description: D,
  props?: ActionCreatorProps<P> & NotAllowedCheck<P>
) {
  return props
    ? createAction(`[${FEATURE_STATE_NAME}] ${description}`, props)
    : createAction(`[${FEATURE_STATE_NAME}] ${description}`);
}

Without the check to see if props is defined, I get an error from createAction. It seems it doesn't allow the props argument to be undefined or null.