ListStore.js

import { createStore } from 'reflux'
// if you don't mind
import { pipe, of } from 'ramda'

import GalleryActions from '../actions/GalleryActions'

export default createStore({

  init(){
    this.galleryMap = {}
    this.listenTo(GalleryActions.listGalleries.completed, this.reduce)
    this.listenTo(GalleryActions.getGallery.completed, pipe(of, this.reduce))
  },

  // most of Stores in Flux architecture just follow a reduce transform
  reduce(galleryList) {
    // TODO: try to avoid mutation, but here is fine
    // reduce could be replaced by merge or extend but also think about immutation
    this.galleryMap = galleryList.reduce(function(sofar, curr) {
      if (curr.id) {
        sofar[curr.id] = curr
      }
      return sofar
    }, this.galleryMap)
    // trigger after mutation immediately
    this.trigger()
  },

  getGalleryById(galleryId){
    return this.galleryMap[galleryId]
  }
})