Este user state for multiple promises

load_user_state.js

import Promise from 'bluebird'
import config from '../config'

export default function loadUserState(req, res, next) {
  const dataSources = [loadMessages(), loadSomeOtherData()]

  if (config.translationServer.loadTranslations)
    dataSources.push(loadTranslations())

  Promise.settle(dataSources).then(receivedData => {
    req.userState = receivedData
      .filter(promise => promise.isFulfilled())
      .map(promise => promise.value())

    next()
  })
}

function loadTranslations() {
  const request = fetch(`${config.translationServer.url}/translations`, {
    method: 'get',
    credentials: 'include',
    headers: {
      'Authorization': `Token token=${config.translationServer.apiKey}`,
      'Content-type': 'application/json'
    }
  })

  return Promise.resolve(request)
    .then(response => response.ok ? response.json() : {})
    .then(i18nData => {
      return {i18n: i18nData}
    })
}

function loadFlashMessages() {
  // ...

  return {flashMessages}
}

state_setup.js

export function appStateForUser(req) {
  const {userState} = req
  return Immutable.fromJS(initialState).mergeDeep(...userState).toJS()
}