src/app/shared/store/reducers/contacts/contacts.reducer.ts

import * as contactsActions from '@shared/store/actions/contacts.action';
import { Contact } from '@shared/models';
import { createReducer, on } from '@ngrx/store';

export interface State {
  loading: boolean;
  loaded: boolean;
  failed: boolean;
  data: Array<Contact>;
}

export const INITIAL_STATE: State = {
  loading: false,
  loaded: false,
  failed: false,
  data: []
};
export const ContactsReducer = createReducer(
  INITIAL_STATE,
  on(contactsActions.loadContacts, (state: any, action: any) => {
    return {
      ...state,
      loading: true,
      loaded: false,
      failed: false,
      data: []
    };
  }),
  on(contactsActions.loadContactsSuccess, (state: any, action: any) => {
    return {
      ...state,
      loading: false,
      loaded: true,
      failed: false,
      data: action['payload']
    };
  }),
  on(contactsActions.loadContactsFail, (state: any, action: any) => {
    return {
      ...state,
      loaded: false,
      loading: false,
      failed: true,
      data: []
    };
  })
);
export function reducer(state = INITIAL_STATE, action: any): State {
  if (!action) {
    return state;
  }

  return ContactsReducer(state, action);
}

export const getData = (state: State) => state.data;
export const getLoading = (state: State) => state.loading;
export const getLoaded = (state: State) => state.loaded;
export const getFailed = (state: State) => state.failed;