Reusing extraSelectors in the createFeature

[alex-aghamyan-volo]

Hi there.
I was wondering is it possible to use selectors defined within extraSelectors in each other?

[markostanimirovic]

Hi @alex-aghamyan-volo 👋

You can define extraSelectors factory in the following way:

export const counterFeature = createFeature({
  name: 'counter',
  reducer: createReducer({ count: 0 }),
  // 👇
  extraSelectors({ selectCount }) {
    const selectCountPlus1 = createSelector(
      selectCount,
      (count) => count + 1
    );
    const selectCountPlus2 = createSelector(
      // 👇
      selectCountPlus1,
      (count) => count + 1
    );

    return { selectCountPlus1, selectCountPlus2 };
  },
});

[alex-aghamyan-volo]

Thank you @markostanimirovic!

[a-boertien]

I ran into the same use case, and it wasn't obvious what the solution was -- thanks for this!

Maybe this should be added to the official docs:
https://ngrx.io/guide/store/feature-creators

[timdeschryver]

@a-boertien that's a good idea. Do you want to create PR for this?
I opened issue #4244 to track this.