gistfile1.js

var userRouter = express.Router(),
    projectsRouter = express.Router();

userRouter.use('/:userId', function (req, res, next) {
  req.user = fetchAndValidate(req.param('userId'));
  next();
});

projectsRouter.use('/', function (req, res, next) {
  res.send(fetchProjects(req.user));
});

projectsRouter.use('/:projectId', function (req, res, next) {
  req.project = fetchAndValidate(req.user, req.param('projectId'));
  next();
});

projectsRouter.get('/:projectId', function (req, res, next) {
  res.send(req.project);
});

projectsRouter.put('/:projectId', function (req, res, next) {
  updateProject(req.user, req.project, req.body);
  res.send(req.project);
});

userRouter.use('/:userId/projects', projectsRouter);