Angular ngrx: Access to an adjacent slice of store

Question

When my component inits, I want to dispatch an action to create the "campaignDraft" object. If the "CampaignOverview" exists, I need to make "campaignDraft" the same, if not exist, make it a preset object {a: 1} e.g.

The problem is that I'm trying to achieve this with Effects, but all my actions lead to browser freezes.

// component.ts
   ngOnInit(): void {
    this.store.dispatch(getCampaignDraft());
    this.campaignFormSubscription = this.store
          .pipe(select(selectCampaignDraft))
          .subscribe((campaignDraft: CampaignModel) => {
            this.campaignForm.patchValue(campaignDraft, { emitEvent: false });
       });
    }
          
 // actions
  export const getCampaignDraft = createAction(CampaignDraftActionTypes.GET_CAMPAIGN_DRAFT);
     
 // effects
     getCampaignDraft$ = createEffect(() => {
        return this.actions$.pipe(
          ofType(fromCampaignDraftActions.getCampaignDraft),
          switchMap((action) => withLatestFrom(this.store.pipe(select(selectCampaignOnly)))),
          map((campaign) => fromCampaignDraftActions.createCampaignDraft({ campaign: {a: 1} })) 
        );
    });

// reducer
  on(campaignDraftActions.createCampaignDraft, (state, { campaign }) => {
    return {
      ...campaign,
    };
  }),

I do not know how to check the Store in effect - does "campaignOverview" exist or not to dispatch another action with this object or the preset one, help please.

Answer 1

we can use withLatestFrom as operator rather than returning it with switchmap, something like below

  getCampaignDraft$ = createEffect(() => {
    return this.actions$.pipe(
      ofType(fromCampaignDraftActions.getCampaignDraft),
      withLatestFrom(this.store.pipe(select(selectCampaignOnly))),
      map(([action, campaign]: [ActionType, CampaginStateSliceType]) => {
        if (exists) {
          return A_Action();
        } else {
          return B_Action();
        }
      })
    );
  })