Mongoose v6.8.0中ID重复问题求助

问题描述 #

我在Mongoose中创建了包含virtuals的Schema，出现了ID重复的情况。查阅官方文档及旧代码，但这些方案均不适用于v6.8.0版本。以下是我的Tour Schema代码，MongoDB中的对象存在_id与id值重复的问题。

原Tour Schema代码 #

/**
 * Import only the mongoose in this class
 * This plugin is for MongoDB and this class decide how the Mongo document should be for the Tour objects
 */
import mongoose from 'mongoose';
import slugify from 'slugify';
/**
 * Config the Tour object what name and the type of attributes
 */
const tourSchema = new mongoose.Schema([
  {
    name: {
      type: String,
      required: [true, 'A tour must have a name'],
      unique: true,
      trim: true,
    },
    slug: String,
    duration: {
      type: Number,
      required: [true, 'A tour must have a duration'],
    },
    maxGroupSize: {
      type: Number,
      required: [true, 'A tour must have a max group size'],
    },
    difficulty: {
      type: String,
      required: [true, 'A tour must have a difficulty'],
    },
    ratingsAverage: {
      type: Number,
      default: 4.5,
    },

    ratingsQuantity: {
      type: Number,
      default: 0,
    },

    price: {
      type: Number,
      required: [true, 'A tour must have a price'],
    },

    priceDiscount: Number,

    summary: {
      type: String,
      trim: true,
      required: [true, 'A tour must have a summary'],
    },
    description: {
      type: String,
      trim: true,
    },
    imageCover: {
      type: String,
      trim: true,
      required: [true, 'A tour must have an cover image'],
    },
    images: [String],

    createAt: {
      type: Date,
      default: Date.now,
      select: false,
    },
    startDates: [Date],
  },
]);
tourSchema.set('toJSON', { getters: true, virtuals: true});
tourSchema.set('toObject', { getters: true, virtuals: true });

tourSchema.virtual('durationWeeks').get(function () {
  return this.duration / 7;
});

// tourSchema.pre('save', function (next) {
//   this.slug = slugify(this.name, { lower: true });
//   next();
// });

// tourSchema.post('save', function(doc,next){
//   console.log(doc);
//   next();
// });


/**
 * Create a mogoose module this puts in the name and type of attributes Tour object should have and what must be writend and what is optional
 */
const Tour = mongoose.model('Tours', tourSchema);
/**
 * Export the Tour constant
 */
export default Tour;

解决方案 #

核心问题定位 #

创建Schema时错误地将字段定义对象包裹在了数组中（new mongoose.Schema([{ ... }])），这会让Mongoose将其解析为Schema数组类型，而非单个文档的Schema结构。这种错误写法会干扰Mongoose默认的ID处理逻辑，再配合开启virtuals: true的配置，就会导致返回结果中同时出现原生_id和虚拟id字段，形成重复。

修复步骤 #

1. 修正Schema创建方式：去掉外层数组，直接传入字段定义对象：

   const tourSchema = new mongoose.Schema({
     name: {
       type: String,
       required: [true, 'A tour must have a name'],
       unique: true,
       trim: true,
     },
     // 其余字段定义保持不变...
   });
   

2. （可选）优化ID返回格式：如果需要统一ID字段展示，可以通过transform函数自定义返回结构，例如只保留id并移除_id：

   tourSchema.set('toJSON', {
     getters: true,
     virtuals: true,
     transform: function(doc, ret) {
       ret.id = ret._id.toString();
       delete ret._id;
       delete ret.__v; // 可选：移除MongoDB默认的版本号字段
     }
   });
   tourSchema.set('toObject', {
     getters: true,
     virtuals: true,
     transform: function(doc, ret) {
       ret.id = ret._id.toString();
       delete ret._id;
       delete ret.__v;
     }
   });
   

验证 #

修复后重新创建或更新文档，MongoDB中只会存储原生的_id字段，返回的JSON/Object结构中不会再出现ID重复的情况，同时虚拟字段durationWeeks仍能正常工作。

内容的提问来源于stack exchange，提问作者Tor Bloodaxe