exports.editUser = async function(req, res, next) {
  try {
    const user = await db.User.findByIdAndUpdate(req.params.id, req.body, {useFindAndModify: false});
    return res.status('200').json(user);
  }
  catch(err) {
    console.log(err);
    return next({
      status: 400,
      message: 'User could not be updated or does not exist.'
    });
  }
};