vue-playgound/src/store/modules/distributor/mutations.js

import * as types from '../../types';
import Vue from 'vue';
import {cloneDeep} from 'lodash';

export default {
    [types.UPDATE_DISTRIBUTORS]: (state, payload) => {
        Vue.set(state, 'distributors', payload);
    },
    [types.UPDATE_DISTRIBUTOR]: (state, payload) => {
        if (payload.id) {
            state.distributors.forEach( (distributor, index) => {
                if (distributor.id === payload.id) {
                    Vue.set(state.distributors, index, payload.distributor[payload.id]);
                } 
            });
        } else {
            Vue.set(state.distributors, state.distributors.length, payload.distributor);
        }
    }
};