Explanation of tweet: https://twitter.com/AlexSashaRegan/status/888439217931419649

vuex-mutation-ex.js

import { Store } from "vuex"

export default new Store({
  state: {
    models: [],
  },
  
  getters: {
    // Caches model references into an object keyed by model id's
    modelsById (state) {
      const dictionary = Object.create(null)
      return state.models.reduce((dict, model) => {
        dict[model.id] = model
        return dict
      }, dictionary)
    }
  },
  
  mutations: {
    UPDATE_MODEL_PROPS (state, {id, props = {}}) {
      // Currently no access to getters, so we must find the model ourselves.
      // Waste of cycles if the list is large.
      const model = state.models.find(m => m.id === id)
      
      // Alternately, if we had the getters:
      const model = getters.modelsById[id]
      
      if (model) {
        Object.assign(model, props)
      }
    },
  },
})