HCPZjRDv

1import _ from 'lodash';
2
3const ALLOWED_MUTATIONS = {
4  set(key) {
5    return (state, action) => ({ [key]: action[key] })
6  },
7
8  increment(key) {
9    return state => ({ [key]: state[key] + 1 });
10  },
11
12  decrement(key) {
13    return state => ({ [key]: state[key] - 1 });
14  },
15
16  updateLoading() {
17    return state => ({ loading: state.requestCount > 0 });
18  }
19};
20
21/**
22 * Experimental mutation wrapper with a chainable api
23 *
24 * e.g Usage
25 *  let fn = m.set('users').andThen.increment('userCount')
26 *
27 *  fn(state, action) => returns the changes to apply to the state
28 *
29 *
30 * @export
31 * @param {*} [muts=[]]
32 * @returns
33 */
34export default function Mutation(muts = []) {
35  let mutationWrapper = function (state, action) {
36    let changes = {};
37    _.chain(muts)
38      .map(fn => fn(state, action))
39      .each(change => _.extend(changes, change));
40    return changes;
41  }
42
43  _.each(ALLOWED_MUTATIONS, (mut, key) => {
44    mutationWrapper[key] = (...params) => {
45      // Build a fresh wrapper with the added mutation
46      return Mutation([ ...muts, mut(...params) ]);
47    }
48  });
49
50  mutationWrapper.andThen = mutationWrapper;
51  mutationWrapper.and = mutationWrapper;
52
53  return mutationWrapper;
54};