'findOne' method doesn't work by following examples

[jmcartlamy]

Issue

By following example on kakapo.js and others to use findOne method, it seems that it doesn't work as well as expected.

It return an empty object instead of my selected data. To fix that, i have to replace

db.findOne('users', userId );

with

db.findOne('users', user => user.id === +userId );

Complete example

export default (router, database) => {
  database.register('users', () => ({
    name: 'Henry',
    phone:  1234567890,
  }));

  database.create('users', 5);

  router.get('/users/:userId', (req, db) => {
    const userId = req.params.userId;
    return db.findOne('users', user => user.id === +userId );
  });
};

import { Database, Router, Server } from 'kakapo';
import mockUsers from './users';

const db = new Database();
const router = new Router();
const server = new Server();

mockUsers(router, db);

server.use(db);
server.use(router);

fetch('/users/2', user => {
  console.log(user);
});