Express 如何在Node.js中不保存相同的电子邮件用户？

我想注册用户，但没有相同的电子邮件

如果电子邮件已经存在，他们将无法注册

由于我的电子邮件字段是一个数组，我不知道如何处理这个问题

---

我收到一个错误“无法读取未定义的“email”属性”

使用嵌套搜索条件：

let user=wait user.findOne（{'emailInfo.email'：emailInfo.email}）；

const UserSchema = new mongoose.Schema({
  firstname: {
    type: String,
  },
  lastname: {
    type: String,
  },
  emailInfo: [
    {
      email: {
        type: String,
        unique: true,
      },
      emailType: String,
    },
  ],

  password: {
    type: String,
  },

registerNewUser: async (req, res) => {
    console.log(req.body);
    const { firstname, lastname, emailInfo, password} = req.body;
    try {
         let user = await User.findOne({ email: emailInfo.email });

       if (user) {
       return res.status(400).json({ msg: "This email id is already in use" });
      }
       user = new User({
        firstname,
        lastname,
        emailInfo,
        password,
      });
      const { emailType, email } = req.body;
      const emailList = { emailType, email };
      user.emailInfo.unshift(emailList);
      const salt = await bcrypt.genSalt(10);
      user.password = await bcrypt.hash(password, salt);
      await user.save()
}