Mongoose ValidationError报错：admin_email类型转换失败 无法调用Nodemailer发信

报错原因 #

核心错误触发点来自Mongoose字段类型校验失败：

• SuperAdminListModel.find({})返回的是符合查询条件的文档数组，你直接将整个数组赋值给了admin_email字段，而AdminUserListSchema中admin_email定义的是String类型，类型不匹配直接触发校验失败
• 额外存在两处代码逻辑问题：
  1. 你将超管查询结果赋值给了superadmin_email变量，但调用dispatch_emails方法时传的是未定义的admin_email变量，会触发引用错误
  2. 新建用户时先执行了一次save，修改密码后又执行了一次save，逻辑冗余；且dispatch_emails方法中使用了res.send，和外层接口的响应逻辑冲突，会触发重复返回响应报错；邮件发送回调中直接抛错没有捕获，会触发未处理的Promise rejection警告。

解决方法 #

1. 修正超管邮箱查询和取值逻辑 #

如果只需要取第一个超管的邮箱，改用findOne查询直接拿到单个文档，再取出邮箱字段：

// 替换原有的超管查询逻辑
const superAdmin = await SuperAdminListModel.findOne({});
if (!superAdmin) {
  return res.status(500).json({ errors: { system: "未查询到超管账号，无法发送通知邮件" } });
}
const admin_email = superAdmin.superadmin_email;

2. 优化注册逻辑，避免冗余操作和错误引用 #

提前完成密码哈希，仅做一次用户保存，修正变量引用：

export const RegisterAdminUser = async (req, res) => {
    try {
        // 超管查询逻辑
        const superAdmin = await SuperAdminListModel.findOne({});
        if (!superAdmin) {
            return res.status(500).json({ errors: { system: "未查询到超管账号" } });
        }
        const admin_email = superAdmin.superadmin_email;
        
        // 校验用户是否存在
        const existingUser = await AdminListModel.findOne({ email: req.body.email });
        if (existingUser) {
            return res.status(409).json({ errors: { email: "用户已存在" } });
        }

        // 提前做密码哈希，仅做一次用户保存
        const hashPassword = await bcrypt.hash(req.body.password, 10);
        const newUser = new AdminListModel({
            admin_email : admin_email,
            company_name: req.body.company_name,
            fullname: req.body.fullname,
            email: req.body.email,
            phone_number: req.body.phone_number,
            timezone: req.body.timezone,
            password: hashPassword
        });

        await newUser.save();
        const token = jwt.sign({ _id: newUser._id, email: newUser.email }, services.JWT_KEY, {
            expiresIn: 31556926,
        });

        // 触发邮件发送
        dispatch_emails(admin_email, newUser.email, newUser.fullname, newUser.company_name);
        
        return res.status(200).json({
            message: "用户注册成功",
            token: token,
            user: newUser,
        });
    } catch (err) {
        return res.status(500).json({ error: err.message });
    }
};

3. 修正邮件发送逻辑，避免冲突和未捕获错误 #

去掉dispatch_emails中的响应返回，添加错误捕获：

const dispatch_emails =(admin_email, email, fullname, company_name) =>{
    const transporter = nodemailer.createTransport({
        service: 'gmail',
        host: 'smtp.gmail.com',
        port: 587,
        auth: {
            user: '*************@gmail.com',
            pass: '************'
        },
        secure: false,
        tls: {
            ciphers: 'SSLv3',
            rejectUnauthorized: false
        }
    });

    const mailOptions = {
        from: '*********@gmail.com',
        to: email,
        subject: 'Account Registration Successful!',
        html: `<h3>Attention,${fullname} , </h3><p><h3>Your Account has been successfully setup.</h3></p><p> Please allow a maximum of 24 - 48 Hours for Review and succesful setup and approval of your online account.</p></br>Regards,</br> Online Services.`
    };

    const AdminNotifyEmail = {
        from: '************@gmail.com',
        to: admin_email,
        subject: `Account Registration for ${email}, with Fullname : ${fullname} (${company_name})`,
        html: `<h3>Attention Admin , </h3><p>A new User has registered his Access with the following Information: </br> <strong>Username : ${email}</strong></br><strong>Company Name : ${company_name}</strong></br><strong>Date of Registration: ${(new Date()).toLocaleString()}</strong></br>Regards</br>Online Services.</p>`
    };

    // 添加错误日志，不要直接抛错
    transporter.sendMail(mailOptions, function (error, info) {
        if (error) console.error('用户注册邮件发送失败：', error);
    })

    transporter.sendMail(AdminNotifyEmail, function (error, info) {
        if (error) console.error('管理员通知邮件发送失败：', error);
    })
}

内容的提问来源于stack exchange，提问作者Keros