animals-helpers.state.ts

@State<AnimalsStateModel>({
  name: 'animals',
  defaults: {
    zebra: {
      food: ['leaves', 'bark'],
      name: 'zebra'
    },
    panda: {
      food: [],
      name: 'panda'
    }
  }
})
export class AppState {
  @Selector()
  public static zebraFood(state: AnimalsStateModel): string[] {
    const zebraFood = [...state.zebra.food];
    zebraFood.reverse();
  }
  
  @Action(Add)
  public add(ctx: StateContext<AnimalsStateModel>, { payload }: Add): void {
    ctx.setState(
      patch({
        zebra: patch({ food: append([ payload ]) })
      })
    );
  }
}