Experimental Redux Mutation Wrapper

redux-mutations.js

import _ from 'lodash';

const ALLOWED_MUTATIONS = {
  set(key) {
    return (state, action) => ({ [key]: action[key] })
  },

  increment(key) {
    return state => ({ [key]: state[key] + 1 });
  },

  decrement(key) {
    return state => ({ [key]: state[key] - 1 });
  },

  updateLoading() {
    return state => ({ loading: state.requestCount > 0 });
  }
};

/**
 * Experimental mutation wrapper with a chainable api
 *
 * e.g Usage
 *  let fn = m.set('users').andThen.increment('userCount')
 *
 *  fn(state, action) => returns the changes to apply to the state
 *
 *
 * @export
 * @param {*} [muts=[]]
 * @returns
 */
export default function Mutation(muts = []) {
  let mutationWrapper = function (state, action) {
    let changes = {};
    _.chain(muts)
      .map(fn => fn(state, action))
      .each(change => _.extend(changes, change));
    return changes;
  }

  _.each(ALLOWED_MUTATIONS, (mut, key) => {
    mutationWrapper[key] = (...params) => {
      // Build a fresh wrapper with the added mutation
      return Mutation([ ...muts, mut(...params) ]);
    }
  });

  mutationWrapper.andThen = mutationWrapper;
  mutationWrapper.and = mutationWrapper;

  return mutationWrapper;
};