expressmongotest/chapter21/18_load_user_middleware.js

var users = require('../../data/users');

function loadUser(req, res, next) {
  var user = req.user = users[req.params.name];
  if (! user) {
    res.send('Not found', 404);
  } else {
    next();
  }
}

module.exports = loadUser;