app.get('/',function(req,res){
    req.flash('error','用户已经注册');
    console.log('--'+req.flash('error'));
    res.render('index', { title: '首页'});
});

app.use(function(req, res, next){
  //res.locals.title = config['title']
  //res.locals.csrf = req.session ? req.session._csrf : '';
  res.locals.user = app.get('user');
  console.log(req.flash('error'));
  res.locals.error = req.flash('error').length ? req.flash('error') : null ;
  res.locals.success = req.flash('success').length ? req.flash('success') : null ;
  next();
});//locals

日志：$ node app Express server listening on port 3000 [] –用户已经注册 GET / 304 561ms [] [] [] []

为什么在视图助手里面无法获取到error的值？？