Nestjs

Question

假设我有两个这样的class

@Injectable({ scope: Scope.DEFAULT })
class Service {
    
    constructor() {}
    // ...
}

@Injectable()
class OtherService {
    param: T;

    constructor(readonly service: Service, param: T) {}

    // ... 
}

我正在尝试使用工厂动态实例化最后一个 class

const otherServiceFactory = {
    provide: "TOKEN",
    scope: Scope.Request,
    useFactory: (req: Request) => {
        const param = req.headers["foo"];
        return new OtherService(/* ts expects an instance of Service here */ , param)
    },
    inject: [REQUEST]
}

正如评论所说，在创建实例时，ts 正确地期望 Service 的实例。问题是我不想弄乱 DI 树，所以我不想实例化 Service。我能够通过稍后设置参数而不是在构造函数中询问来解决这个问题，所以我不再需要工厂了，但感觉非常次优。有什么建议吗？

谢谢

Answer 1

您可以将Service添加到inject数组，并获取Nest创建的Service的实例，然后将其传递给OtherService，这样您就拥有了一切需要创建 class.

const otherServiceFactory = {
    provide: "TOKEN",
    scope: Scope.Request,
    useFactory: (req: Request, service: Service) => {
        const param = req.headers["foo"];
        return new OtherServiceservice, param)
    },
    inject: [REQUEST, Service]
}

Nestjs - 手动实例化 class 依赖于 useFactory

Nestjs - Manually instantiate a class with dependencies on useFactory

dependency-injection

typescript