node+express处理登录的时候出错

Question

这是index.js中登录的代码

app.get( '/login', function (req, res) {
        res.render( 'login', { title:'登录' });
    });
    app.post( '/login', function (req, res) {
        //生成密码的md5值
        var md5 = crypto.createHash('md5'),
              password = md5.update(req.body.password).digest('hex');
        //检查用户是否存在
        User.get(req.body.name, function (err, user) {
            if (!user) {
                req.flash('error','用户不存在！');
                return res.redirect('/login');//用户不存在则跳转到登录页
            }
            //检查密码是否一致
            if (user.password != password) {
                req.flash('error','密码错误！');
                return res.redirect('/login');//密码错误则跳转到登录页
            }
            //用户名密码都匹配后，将用户信息存入session
            req.session.user = user;
            req.flash('success','登录成功！');
            res.redirect('/');//登录成功后跳转到主页
        });

但是运行后出现错误，为：

Express
500 ReferenceError: /home/lu/node/blog/views/login.ejs:15<br/><br/><br/>user is not defined
user is not defined
at __line (eval at (/home/lu/node/blog/node_modules/ejs/lib/ejs.js:464:12), :14:12)
at eval (eval at (/home/lu/node/blog/node_modules/ejs/lib/ejs.js:464:12), :39:9)
at returnedFn (/home/lu/node/blog/node_modules/ejs/lib/ejs.js:493:17)
at View.exports.renderFile [as engine] (/home/lu/node/blog/node_modules/ejs/lib/ejs.js:350:31)
at View.render (/home/lu/node/blog/node_modules/express/lib/view.js:76:8)
at Function.app.render (/home/lu/node/blog/node_modules/express/lib/application.js:504:10)
at ServerResponse.res.render (/home/lu/node/blog/node_modules/express/lib/response.js:801:7)
at /home/lu/node/blog/routes/index.js:60:7
at callbacks (/home/lu/node/blog/node_modules/express/lib/router/index.js:164:37)
at param (/home/lu/node/blog/node_modules/express/lib/router/index.js:138:11)

求高人解答。。。

Answer 1

修改代码为：

app.get( '/login', function (req, res) {
        res.render('login', { 
            title:'登录',
            user:req.session.user,
            success: req.flash('success').toString(),
            error: req.flash('error').toString()
             });

Answer 2

要学会看报错：
报错已经写得很清楚了user is not defined，就是说你的user没有定义，没有这个东西存在你就引用了。
代码在/home/lu/node/blog/routes/index.js的60行里。