The user service for Nest.js - https://blog.entrostat.com/setting-up-a-database-module-in-nest-js/

user.service.ts

import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { User } from 'modules/shared/entities/user.entity';
import { Repository } from 'typeorm';

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

    }
}