问我不明白注入依赖是如何工作的。有没有人能给我解释清楚

EN

import {
  Injectable,
  Inject,
  UnprocessableEntityException,
  HttpStatus,
} from '@nestjs/common';
import { Repository } from 'typeorm';
import * as bcrypt from 'bcryptjs';
import { User, UserStatus } from './user.entity';
import { LoggerService } from '../../../logger/logger.service';
import { HammerErrors } from 'src/error/hammer.errors';
import * as Config from '../../../config/global.env';

@Injectable()
export class UserService {
  private readonly _logger = new LoggerService(UserService.name);

  constructor(
    @Inject('USER_REPOSITORY')
    private _userRepository: Repository<User>,
  ) {}
  ....
  async reactiveBlockedUsers() {
    this._logger.setMethod(this.reactiveBlockedUsers.name);
    this._logger.log(`Update blocked users`);
    await this._userRepository
      .createQueryBuilder('hm_users')
      .update(User)
      .set({
        nextValidDate: null,
      })
      .where(
        `hm_users.nextValidDate IS NOT NULL hm_users.nextValidDate < utc_timestamp()`,
      )
      .execute();
    return null;
  }

import { LoggerService } from '../../../logger/logger.service';
import { UserService } from '../../providers/user/user.service';
import { Injectable } from '@nestjs/common';
import { Cron, CronExpression } from '@nestjs/schedule';

@Injectable()
export class TasksService {
  private _logger = new LoggerService(TasksService.name);

  constructor(private _userService: UserService) {}

  @Cron(CronExpression.EVERY_MINUTE)
  async reactiveUsers() {
    this._logger.setMethod(this.reactiveUsers.name);
    this._logger.log(`Reactive blocked users`);
    try {
      await this._userService.reactiveBlockedUsers();
    } catch (error) {
      this._logger.log(error);
    }
  }

  @Cron(CronExpression.EVERY_MINUTE)
  startBatchJobs() {
    this._logger.setMethod(this.startBatchJobs.name);
    this._logger.log(`Start batch job service`);
  }

  triggerNotifications() {}
}

import { Module } from '@nestjs/common';
import { TasksService } from './tasks.service';
import { UserService } from 'src/shared/providers/user/user.service';
import { Repository } from 'typeorm';

@Module({
  providers: [
    TasksService,
    UserService,
    {
      provide: 'USER_REPOSITORY',
      useClass: Repository,
    },
  ],
})
export class TasksModule {}