如何在使用nestjs query Builder生成的查询中动态添加where子句？

import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, SelectQueryBuilder } from 'typeorm';
import { User } from './user.entity';

@Injectable()
export class UserService {
  constructor(
    @InjectRepository(User)
    private userRepository: Repository<User>,
  ) {}

  async getUsersWithDynamicWhereClause(name?: string, age?: number): Promise<User[]> {
    let queryBuilder: SelectQueryBuilder<User> = this.userRepository.createQueryBuilder('user');

    if (name) {
      queryBuilder = queryBuilder.andWhere('user.name = :name', { name });
    }

    if (age) {
      queryBuilder = queryBuilder.andWhere('user.age = :age', { age });
    }

    return queryBuilder.getMany();
  }
}