我想自动添加_id到数组中的所有对象。我正在使用nestjs框架的mongoose。

我的schema看起来像

import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';
export type PropModel = newSchemaDetail & Document;
@Schema()
export class Prop3 {
  @Prop({ type: String, required: true })
  prop3.1: string;
  @Prop({ type: String, required: true })
  prop3.2: string;
}
@Schema()
export class Prop4{
@Prop({ type: String, required: true })
  prop4.1: string;
  @Prop({ type: String, required: true })
  prop4.2: string;}

@Schema()
export class newSchemaDetail {
  @Prop({ type: String, required: true })
  prop1: string;
  @Prop({ type: String, required: false }) 
  prop2: string;
  @Prop({ type: Array<Prop3>, required: true })
  prop3: Prop3[];
 @Prop({ type: Prop3, required: true }) 
prop4:Prop4
 
}
export const PropSchema = SchemaFactory.createForClass(newSchemaDetail);

结果

{
  "prop1": "xyz",
  "prop2": "abc",
  "prop3": [
    {
      "prop3.1": "kgkhkmfe",
      "prop3.2": "nbjfmlkgh"
    }
  ],
  "prop4":{"_id":"646b99d74abf7c25e21tx85","prop4.1":"test","prop4.2":"test2"},
  "_id": "646c99e74bcf7b25d21cyb85",
  "__v": 0
}

预期

{
  "prop1": "xyz",
  "prop2": "abc",
  "prop3": [
    {
      "_id":"646b99d47abf7c56e21tx89"
      "prop3.1": "kgkhkmfe",
      "prop3.2": "nbjfmlkgh"
    }
  ],
  "prop4":{"_id":"646b99d74abf7c25e21tx85","prop4.1":"test","prop4.2":"test2"},
  "_id": "646c99e74bcf7b25d21cyb85",
  "__v": 0
}

为什么@Schema()不能处理对象数组，或者我做错了什么。有人能告诉我如何得到我期望的结果吗？
先谢谢你了！