Node.js 未在猫鼬上显示的虚拟和填充

我做错什么了吗？我一直在尝试在派对上展示虚拟场景，我尝试了简单的虚拟场景，比如“标语”，只是为了验证一下。我也有填充问题。我有点讨厌这个，因为它没有给我任何错误或警告，我也不知道它背后发生了什么。有点令人沮丧

   const mongoose = require('mongoose');
mongoose.set("debug", true);

const partySchema = mongoose.Schema({
   name: {
       type: String,
       required: [true, 'Please provide a party'],
       unique: [true, 'Party already exists. Please try another party name'],
       maxLength: [20, 'Party Name should be less than 20 characters'],
       minLength: [4, 'Party Name should be greater than 4 characters']
   },
   slogan:{
       type: String,
       required: [true, 'Please provide a slogan'],
       maxLength: [20, 'Party Name should be less than 20 characters'],
       minLength: [5, 'Party Name should be greater than 5 characters']
   },
   createdAt:{
       type: Date,
       default: Date.now()
   }
},{
   toObject: {
       virtuals: true
     }
     ,toJSON: {
       virtuals: true
     }
});

partySchema.virtual('slogans').get(function () {
   // use an ordinary function so you can get the "this"
   return this.slogan
});

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外部id不是ObjectId数据类型

外部id不是ObjectId数据类型