nestjs 依赖注入方面的 “Bug” ｜ custom providers

原创已于 2022-09-12 19:20:09 修改 · 569 阅读

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#bug #nestjs

于 2022-05-29 23:20:41 首次发布

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本文探讨了在NestJS框架中遇到的依赖注入问题，通过分析两个不同场景——场景一和场景二，揭示了问题的本质。作者指出，这些问题并非NestJS的bug，而是需要正确理解和使用自定义提供者。详细解决方案可参考NestJS官方文档，该文档详细介绍了如何在NestJS中创建和使用自定义提供者。

场景一

写法一：

export class InfrastructureStackService {
  constructor(
    private manager: InfrastructureStackManager = InfrastructureStackManager.PULUMI
  ) {}
}

写法二：

export class InfrastructureStackService {
  private manager: InfrastructureStackManager =
    InfrastructureStackManager.PULUMI;

  constructor() {}
}

场景二


@Injectable()
export class SqsService {
  private client: SQSClient;
  private queueUrl: string;

  constructor(params: {queueUrl: string}) {
    this.client = new SQSClient({
      region: AwsConfig.getRegion(), // region is required for SQS service.
    });

    this.queueUrl = params.queueUrl.toString();
  }

}

[9:15:20 AM] Found 0 errors. Watching for file changes.

[Nest] 96503  - 09/12/2022, 9:15:25 AM     LOG [NestFactory] Starting Nest application...
[Nest] 96503  - 09/12/2022, 9:15:25 AM     LOG [InstanceLoader] PrismaModule dependencies initialized +82ms
[Nest] 96503  - 09/12/2022, 9:15:25 AM   ERROR [ExceptionHandler] Nest can't resolve dependencies of the SqsService (?). Please make sure that the argument Object at index [0] is available in the AwsModule context.

Potential solutions:
- If Object is a provider, is it part of the current AwsModule?
- If Object is exported from a separate @Module, is that module imported within AwsModule?
  @Module({
    imports: [ /* the Module containing Object */ ]
  })

最终答案在这里 Documentation | NestJS - A progressive Node.js frameworkNest is a framework for building efficient, scalable Node.js server-side applications. It uses progressive JavaScript, is built with TypeScript and combines elements of OOP (Object Oriented Progamming), FP (Functional Programming), and FRP (Functional Reactive Programming).https://docs.nestjs.com/fundamentals/custom-providers