Curried Reducers

index.js

import { combineReducers } from "redux";
import listReducer from "./listReducer";

const rootReducer = combineReducers({
  products: listReducer("products"),
  orders: listReducer("orders"),
  warehouse_locations: listReducer("warehouse_locations")
});

export default rootReducer; // later configured in store

listReducer.js

// Paginated List Reducer
import { combineReducers } from "redux";

const listReducer = listType => {
  const type = listType.toUpperCase();
  
  const status = (state = null, action) => {
    switch (action.type) {
      case `REQUEST_${type}`:
        return "inprogress";
      case `FETCH_${type}_SUCCESS`:
        return "success";
      case `FETCH_${type}_FAILURE`:
        return "failure";
      default:
        return state;
    }
  };

  const items = (state = [], action) => {
    switch (action.type) {
      case `FETCH_${type}_SUCCESS`:
        return action.items;
      case `FETCH_${type}_FAILURE`:
        return []; // reset existing data
      default:
        return state;
    }
  };

  // Total number of items in the list (in all pages)
  const totalCount = (state = 0, action) => {
    switch (action.type) {
      case `FETCH_${type}_SUCCESS`:
        return action.totalCount;
      case `FETCH_${type}_FAILURE`:
        return 0; // reset existing data
      default:
        return state;
    }
  };

  const totalPages = (state = 0, action) => {
    switch (action.type) {
      case `FETCH_${type}_SUCCESS`:
        return action.totalPages;
      case `FETCH_${type}_FAILURE`:
        return 0; // reset existing data
      default:
        return state;
    }
  };

  return combineReducers({
    status,
    items,
    totalCount,
    totalPages
  });
};

export default listReducer;