Node.js 如何在同一Mongoose模式中将字符串与另一个键值连接起来

是否可以在同一Mongoose模式中连接字符串和前一个键值的值？下面的响应为未定义帐户

const mongoose = require("mongoose");
const Schema = mongoose.Schema;

let TrackingSchema = new Schema({
    account: { type: String, required: true, max: 100 },
    accountURL: "https://www.instagram.com/" + account,
    followedBack: { type: Number, required: true }
},
{
    timestamps: true
});

// Export the model
module.exports = mongoose.model("Tracking", TrackingSchema);

您可以创建一个：

TrackingSchema.virtual('accountURL').get(function(){
    return "https://www.instagram.com/" + this.account;
});