Utilities to handle common reducer actions when dealing with normalized data

utilities.js

import set from 'lodash/fp/set';
import get from 'lodash/fp/get';
import omit from 'lodash/fp/omit';
import pipe from 'lodash/fp/pipe';

const removeFromArray = (array, target) => array.filter(n => n !== target);

export const addEntity = (state, entity, id) => {
  return pipe(
    set(['entities', id], entity),
    set('ids', state.ids.concat(id)),
  )(state);
};

export const removeEntity = (state, id) => {
  return pipe(
    omit(`entities.${id}`),
    set('ids', removeFromArray(state.ids, id)),
  )(state);
};

export const addIdToChildren = (state, entityId, property, childId) => {
  const path = ['entities', entityId, property];
  const children = get(path)(state);
  return set(path, children.concat(childId), state);
};

export const removeIdFromChildren = (state, entityId, property, childId) => {
  const path = ['entities', entityId, property];
  const children = get(path)(state);
  return set(path, removeFromArray(children, childId), state);
};


// Eample
// someReducer.js
/* 
import { RESOURCE_CREATE, RESOURCE_DELETE } from '../actions/resource-actions';

import { addEntity, removeEntity } from './_utilities';

const resourceReducer = (state = initialState, action) => {
  if (action.type === RESOURCE_CREATE) {
    const { resource, resourceId } = action.payload;
    return addEntity(state, resource, resourceId);
  }

  if (action.type === RESOURCE_DELETE) {
    const { resourceId } = action.payload;
    return removeEntity(state, resourceId);
  }

  return state;
};

export default resourceReducer;
 */