MongoDB Driver + Express.js 简单注册 MongoError: E11000

你好。

在充满回调的 MongoDB Driver 上有一个简单的注册，我决定使用 asyc / await 重写。但是有一个错误。它与什么有关，我不明白。有人可以解释吗？谢谢）

蒙戈错误：

index: name_1 dup key: { : null }E11000 重复键错误集合：FirstApp.users

编码：

const config = require ('../config');
const mongodb = require ('mongodb');
const ObjectId = require('objectid');
const express = require ('express');
const router = express.Router();
const MongoClient = mongodb.MongoClient;
const DBurl = config.DBurl;

const SaveUser = async function (UserEmail, UserPassword, sessionID) {

    const User = {
        //_id: new ObjectId(),
        "UserEmail": UserEmail,
        "UserPassword": UserPassword,
        "SessionID": sessionID,
    };

    console.log(User);

    try {
        const db = await MongoClient.connect(DBurl);

        const collection = db.collection('users');

        //collection.createIndex({"name" : 1}, {"unique" : true});
        const result = await collection.insertOne(User);

        if (result.acknowledged)
            return {save: true};

        else
            return {save: false};

    } catch (e) {
        return e;
    }
};

const Register = router.post("/", async (req, res) => {
    const UserEmail = req.body.UserEmail;
    const UserPassword = req.body.RegisterPassword;
    const UserConfirmPassword = req.body.confirmPassword;
    const sessionID = req.sessionID;

    if (UserPassword === UserConfirmPassword) {

        const result = await SaveUser(UserEmail, UserPassword, sessionID);

        result.save ?
            res.status(200)
                .json({isBusy: false}) :
            res.status(500)
                .json({error: result, isBusy: true});
    }

    else if(UserEmail || UserPassword || UserConfirmPassword === undefined)
        res.status(400)
            .send('Bad request');

    else if (UserConfirmPassword !== UserPassword)
    res.status(400)
            .send('Wrong confirm password');
});
module.exports = Register;