在Nest.js中除Provider外，有无更优雅的Drizzle ORM使用方式？

问题背景 #

当前使用Drizzle ORM时，需要通过自定义Provider常量（如PG_CONNECTION）注入数据库连接，每次使用都要导入该常量和数据库类型，写法繁琐。希望能像Prisma的PrismaService一样，直接注入一个服务类即可便捷操作。

解决方案：封装DrizzleService #

通过创建一个DrizzleService类封装Drizzle实例，替代原有的常量Provider，实现类似PrismaService的简洁用法。

1. 创建DrizzleService #

import { Injectable, OnModuleDestroy } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { drizzle } from 'drizzle-orm/postgres-js';
import postgres from 'postgres';
import * as schema from './schema';

@Injectable()
export class DrizzleService implements OnModuleDestroy {
  public readonly db: ReturnType<typeof drizzle<typeof schema>>;
  private readonly client: ReturnType<typeof postgres>;

  constructor(private configService: ConfigService) {
    // 初始化PostgreSQL客户端
    this.client = postgres(this.configService.get<string>('DATABASE_URL'));
    // 初始化Drizzle实例
    this.db = drizzle(this.client, { schema });
  }

  // 模块销毁时自动关闭数据库连接
  async onModuleDestroy() {
    await this.client.end();
  }
}

2. 修改DrizzleModule #

将原来的常量Provider替换为DrizzleService，并导出该服务供其他模块使用：

import { Module } from '@nestjs/common';
import { ConfigModule } from '@nestjs/config';
import { DrizzleService } from './drizzle.service';

@Module({
  imports: [ConfigModule],
  providers: [DrizzleService],
  exports: [DrizzleService],
})
export class DrizzleModule {}

3. 在业务服务中使用 #

现在可以像使用PrismaService一样简洁地注入DrizzleService，直接通过db属性操作数据库：

import { Injectable } from '@nestjs/common';
import { DrizzleService } from '../drizzle/drizzle.service';

@Injectable()
export class UsersService {
  constructor(private drizzleService: DrizzleService) {}

  async findAll() {
    return await this.drizzleService.db.query.users.findMany();
  }
}

进阶优化：直接代理Drizzle实例（可选） #

如果希望写法完全贴近PrismaService（无需.db前缀），可以让DrizzleService代理Drizzle实例的所有属性和方法：

import { Injectable, OnModuleDestroy } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { drizzle } from 'drizzle-orm/postgres-js';
import postgres from 'postgres';
import * as schema from './schema';

type DrizzleInstance = ReturnType<typeof drizzle<typeof schema>>;

@Injectable()
export class DrizzleService implements OnModuleDestroy, DrizzleInstance {
  private readonly db: DrizzleInstance;
  private readonly client: ReturnType<typeof postgres>;

  constructor(private configService: ConfigService) {
    this.client = postgres(this.configService.get<string>('DATABASE_URL'));
    this.db = drizzle(this.client, { schema });

    // 代理Drizzle实例的所有属性和方法
    return new Proxy(this, {
      get(target, prop) {
        if (prop in target) {
          return Reflect.get(target, prop);
        }
        return Reflect.get(target.db, prop);
      },
    });
  }

  async onModuleDestroy() {
    await this.client.end();
  }

  // 声明核心属性以满足TypeScript类型检查
  get query() {
    return this.db.query;
  }

  get select() {
    return this.db.select;
  }
}

此时业务服务中的用法就和PrismaService完全一致：

import { Injectable } from '@nestjs/common';
import { DrizzleService } from '../drizzle/drizzle.service';

@Injectable()
export class UsersService {
  constructor(private drizzle: DrizzleService) {}

  async findAll() {
    return await this.drizzle.query.users.findMany();
  }
}

内容的提问来源于stack exchange，提问作者kilian.sch