为什么req对象中缺少我的用户对象?

以下函数UserService.sign in()调用服务器以登录用户:

public signIn(credentials) {
    let body = JSON.stringify(credentials);

    return this.httpClient.post(this.userUrl, body, httpOptions)
    .pipe(
      map(token => {
        this.cartService.getCart().subscribe();
      }),
      catchError(this.handleError.bind(this))
    )    
  }

服务器的signIn函数将用户对象存储在req对象上,如图所示:req.user=user。req.user被记录到控制台并显示期望值。

user.server.controller登录()

exports.signin = function(req, res) {
    const email = req.body.email;
    const password = req.body.password;

    User.findOne({
        email:email
    }).exec(function(err, user) {
        if(err) {      
        } else if(user == null) { 
            }else {
                if(bcrypt.compareSync(password, user.password)) {
                    console.log('user found', user)
                    var token = jwt.sign({name:user.name, email:user.email}, 
                        config.sessionSecret, {expiresIn:3600});
                    req.user = user;
                    console.log('\nuser.server.controller#req.user', req.user)
                    res.status(200).json(token);
                   return;
                } else {
            }
        }
    })
}

 map(token => {
    this.cartService.getCart().subscribe();
 }),

然后调用服务器检索用户的购物车,如图所示:

public getCart() {
    return this.httpClient.get(this.cartUrl)
    .pipe(
      tap(cart => this.logger.log('cart', cart))
    )
 }

在cart.server.controller#getCart()中,我尝试使用先前在调用user.server.controller#signIn()期间保存到req对象的req.user电子邮件,但我得到一个错误,req.user未定义。

cart.server.controller获取购物车()

exports.getCart = function (req, res) {
    Cart.findOne({
        email: req.user.email
    }).exec(function (err, cart) {

    })
}