To receive data from the network, validate it, and transform it using class-validator and class-transformer, you can follow these steps:

logic.ts

async function createUser(userData: any): Promise<Document> {
  const user = plainToClass(User, userData, { excludeExtraneousValues: true });
  const errors = await validate(user);

  if (errors.length > 0) {
    throw new Error(`Validation failed: ${JSON.stringify(errors)}`);
  }

  const createdUser = await model('User').create(user);

  return createdUser;
}

user.dto.ts

import { IsString, IsMongoId } from 'class-validator';
import { Transform, Type } from 'class-transformer';
import { Schema, Document, model } from 'mongoose';

class User {
  @Transform(({ value }) => Schema.Types.ObjectId(value), { toClassOnly: true })
  @Type(() => String)
  @IsMongoId()
  _id: Schema.Types.ObjectId;

  @IsString()
  name: string;
}