学习《Node.js开发指南》遇到一个问题：动态视图的实现问题 首先书中第五章sample中‘视图交互’一节： app.dynamicHelpers({ user:function(req,res){ return res.session.user; }, error:function(req,res){ var err = req.flash(‘error’); if(err.length) return err; else return null; }, success:function(req,res){ var succ = req.flash(‘success’); if(succ.length) return succ; else return null; } }); 此版本在Express 3.0之后就不支持了，网上介绍使用 res.locals代替： app.use(function(req,res,next){ var err = req.flash(‘error’); var success = req.flash(‘success’); res.locals.user = req.session ? req.session.user : null; res.locals.error = err.length ? err : null; res.locals.success = success.length ? success : null; next(); }); app.use(app.router); routes(app); 问题是我如此做一直没有效果，即视图的效果没有，我的请求不会调用这段逻辑，我在此方法里面断点debugger了，可是一直执行不到，直接导致res.locals.user，error，success的值一直都是undefinded。

我想请教大家，这个动态视图是如何实现的，我的问题出在哪里？ var express = require(‘express’); var routes = require(’./routes’); var user = require(’./routes/user’); var http = require(‘http’); var path = require(‘path’); var util = require(‘util’); var flash = require(‘connect-flash’);

var app = express(); var engine = require(‘ejs-locals’); var MongoStore = require(‘connect-mongo’)(express); var settings = require(’./settings’); var sessionStore = new MongoStore({ db : settings.db }, function() { console.log(‘connect mongodb success…’); });

app.configure(function () { // all environments app.set(‘port’, process.env.PORT || 3000); //since express 3.0 use ejs-locals app.engine(‘ejs’, engine);

app.set(‘views’, __dirname + ‘/views’); app.set(‘view engine’, ‘ejs’); app.use(express.favicon()); app.use(express.logger(‘dev’)); app.use(express.bodyParser()); app.use(flash()); app.use(express.methodOverride());

app.use(express.cookieParser()); app.use(express.session({ secret:settings.cookieSecret, cookie : { maxAge : 60000 * 20 //20 minutes }, store:sessionStore }));

app.use(function(req,res,next){ var err = req.flash(‘error’); var success = req.flash(‘success’); res.locals.user = req.session ? req.session.user : null; res.locals.error = err.length ? err : null; res.locals.success = success.length ? success : null; next(); }); app.use(app.router); app.use(express.static(path.join(__dirname, ‘public’))); });

// development only if (‘development’ == app.get(‘env’)) { app.use(express.errorHandler()); } routes(app);

http.createServer(app).listen(app.get(‘port’), function(){ console.log('Express server listening on port ’ + app.get(‘port’)); }); 插件我也都装了： { “name”: “aine blog”, “version”: “0.0.1”, “private”: true, “scripts”: { “start”: “node app.js” }, “dependencies”: { “express”: “3.3.8”, “ejs”: “", “connect”: “1.8.5”, “connect-mongo”:">= 0.1.7", “mongodb”:">= 0.0.9", “connect-flash”:"” } } 是不是什么插件版本不兼容呢？请高手指教。。。。