user-serialize.js

import serialize from 'stacks/serialize';
import Team from 'stacks/model/team';

let user = serialize('user')
  // We want to expose the key `token` under the key `id`, replacing
  // whatever `id` used to be.
  .map('token', 'id')
  // A promise mapping, allowing us to take a single
  // key and returning a promise. The resolved value
  // must be of the format:
  //
  //  `{ key: String, value: Any }` 
  .mapPromise('team_id', id => {
    return Team.forge({ id: id })
      .fetch()
      .then(team => {
        // If we don't have a team, return a nullified key named `team`.
        if (!team) {
          return { key: 'team', value: null }
        }
        
        return { key: 'team', value: team.get('token') };
      });
  });