nest object scalar

ObjectIdScalar.ts

import { Scalar, CustomScalar } from '@nestjs/graphql';
import { Kind, ValueNode } from 'graphql';

import { ObjectId } from 'mongodb';

@Scalar('ObjectId')
export class ObjectIdScalar implements CustomScalar<string, ObjectId> {
  description = '`Date`';
  parseLiteral(ast): ObjectId {
    // check the type of received value
    if (ast.kind !== Kind.STRING && ObjectId.isValid(ast.value)) {
      return new ObjectId(ast.value); // value from the client input variables
    }
    throw new Error(`invalid input "${ast.value}"`);
  }
  serialize(value: unknown): string {
    // check the type of received value
    if (!(value instanceof ObjectId)) {
      throw new Error('ObjectIdScalar can only serialize ObjectId values');
    }
    return value.toHexString(); // value sent to the client
  }
  parseValue(value: unknown): ObjectId {
    // check the type of received value
    if (typeof value === 'string' && ObjectId.isValid(value)) {
      return new ObjectId(value); // value from the client input variables
    }
    throw new Error(`invalid input "${value}"`);
  }
}