Node.js Passport.js 身份验证失败时发回 JSON 响应

我使用Node.js作为iPhone客户端的后端API服务器.我用Passport.js来验证local strategy.相关代码如下:

// This is in user.js, my user model
UserSchema.static('authenticate', function(username, password, callback) {
    this.findOne({ username: username }, function(err, user) {
        if (err){
            console.log('findOne error occurred');
            return callback(err);
        }
        if (!user){
            return callback(null, false);
        }
        user.verifyPassword(password, function(err, passwordCorrect){
            if (err){
                console.log('verifyPassword error occurred');
                return callback(err);
            }
            if (!passwordCorrect){
                console.log('Wrong password');
                return callback(err, false);
            }
            console.log('User Found, returning user');
            return callback(null, user);
        });
    });
});

和

// This is in app.js
app.get('/loginfail', function(req, res){
    res.json(403, {message: 'Invalid username/password'});
});

app.post('/login',
    passport.authenticate('local', { failureRedirect: '/loginfail', failureFlash: false }),
    function(req, res) {
       res.redirect('/');
});

现在，我成功地将一个失败的登录重定向到/loginfail，在那里我将一些JSON发送回iPhone客户端.然而，这并没有足够的粒度.我希望能够将适当的错误发送回iPhone客户端，例如:"未找到用户"或"密码错误".用我现有的代码，我看不出这是如何实现的.

I tried to follow the examples for a custom callback on the passport.js site, but I just can't get it to work due to lack of node underst和ing. How could I modify my code so that I'd be able to send back a res.json with an appropriate error code/message?

我现在正在try 这样的事情:

// In app.js
app.post('/login', function(req, res, next) {
    passport.authenticate('local', function(err, user, info) {
        if (err) { return next(err) }
        if (!user) {
            console.log(info);
            // *** Display message without using flash option
            // re-render the login form with a message
            return res.redirect('/login');
        }
        console.log('got user');
        return res.json(200, {user_id: user._id});
    })(req, res, next);
});

// In user.js
UserSchema.static('authenticate', function(username, password, callback) {
    this.findOne({ username: username }, function(err, user) {
        if (err){
            console.log('findOne error occurred');
            return callback(err);
        }
        if (!user){
            return callback(null, false);
        }
        user.verifyPassword(password, function(err, passwordCorrect){
            if (err){
                return callback(err);
            }
            if (!passwordCorrect){
                return callback(err, false, {message: 'bad password'});
            }
            console.log('User Found, returning user');
            return callback(null, user);
        });
    });
});

但当我试图安慰的时候.日志(log)(信息)，它只是说未定义.我不知道如何让这个自定义回调正常工作...任何帮助都将不胜感激！