How to add _id automatically to an array of object in nestjs mongoose

Question

I want to add _id automatically to all object inside an array.I am using mongoose with nestjs framework.

my schema looks like

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);

result

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

expected

{
  "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
}

Why @Schema() is not working with array of object or am I doing something wrong.Can anyone tell how to get my expected result.

Thanks in advance!

Answer 1

First you should create a schema for Prop3 like this:

const Prop3Schema = SchemaFactory.createForClass(Prop3);

And replace the line @Prop({ type: Array<Prop3>, required: true }) with the following.

@Prop({ type: [Prop3Schema], required: true })