Nest无法找到PrismaService，main.ts调用服务崩溃求助

在main.ts中尝试获取PrismaService时服务持续崩溃，移除相关代码后服务器可正常启动。以下是相关代码、报错信息及解决方案：

相关代码 #

prisma.service.ts #

import { INestApplication, Injectable, OnModuleInit } from '@nestjs/common';
import { PrismaClient } from '@prisma/client';

@Injectable()
export class PrismaService extends PrismaClient implements OnModuleInit {
  async onModuleInit() {
    await this.$connect();
  }

  async enableShutdownHooks(app: INestApplication) {
    this.$on('beforeExit', async () => {
      await app.close();
    });
  }
}

main.ts #

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { PrismaService } from './prisma.service';
import { ValidationPipe } from '@nestjs/common';
import helmet from 'helmet';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  app.enableCors({
    allowedHeaders: '*',
    origin: '*',
  });
  app.use(helmet());
  app.use(helmet.hidePoweredBy());
  app.use(helmet.contentSecurityPolicy());

  const prismaService = app.get(PrismaService);
  await prismaService.enableShutdownHooks(app);

  app.useGlobalPipes(
    new ValidationPipe({
      transform: true,
      whitelist: true,
      forbidNonWhitelisted: true,
    }),
  );

  await app.listen(process.env.PORT, () => console.log('runing...'));
}
bootstrap();

报错信息 #

Error: Nest could not find PrismaService element (this provider does not exist in the current context)
    at InstanceLinksHost.get (/home/rafittu/wophi/alma/back/node_modules/@nestjs/core/injector/instance-links-host.js:15:19)
    at NestApplication.find (/home/rafittu/wophi/alma/back/node_modules/@nestjs/core/injector/abstract-instance-resolver.js:8:60)
    at NestApplication.get (/home/rafittu/wophi/alma/back/node_modules/@nestjs/core/nest-application-context.js:64:20)
    at /home/rafittu/wophi/alma/back/node_modules/@nestjs/core/nest-factory.js:133:40
    at Function.run (/home/rafittu/wophi/alma/back/node_modules/@nestjs/core/errors/exceptions-zone.js:10:13)
    at Proxy.<anonymous> (/home/rafittu/wophi/alma/back/node_modules/@nestjs/core/nest-factory.js:132:46)
    at Proxy.<anonymous> (/home/rafittu/wophi/alma/back/node_modules/@nestjs/core/nest-factory.js:181:54)
    at bootstrap (/home/rafittu/wophi/alma/back/src/main.ts:18:29)

问题原因及解决方法 #

报错核心原因是未在AppModule中注册PrismaService作为提供者，NestJS的依赖注入系统只能识别已在模块中注册的服务。

解决步骤 #

1. 打开app.module.ts文件，导入PrismaService
2. 在providers数组中添加PrismaService

修改后的app.module.ts示例：

import { Module } from '@nestjs/common';
import { PrismaService } from './prisma.service';
// 导入你项目中的其他模块/控制器

@Module({
  imports: [/* 你的其他导入模块 */],
  controllers: [/* 你的控制器 */],
  providers: [PrismaService], // 必须在此处添加PrismaService
})
export class AppModule {}

额外说明 #

• 确保PrismaService的导入路径正确，避免因路径错误导致无法识别
• 注册完成后，NestJS会自动实例化PrismaService，此时在main.ts中通过app.get(PrismaService)即可正常获取实例

内容的提问来源于stack exchange，提问作者Rafael Ribeiro