Annotation for Auto Creation of Singleton Service

Suppose we are doing this in app.component.ts

  constructor(assets: AssetsService) {}

The AssetsService is not actually used. We just rely on the constructor to fetch assets like SVG custom icons etc.

It would be nice not to have to inject it on boot in order to get the constructor to run. Something like:

@AutoConstruct()
export class AssetsService {

  constructor(
    private matIconRegistry: MatIconRegistry,
    private domSanitizer: DomSanitizer) {
    {
      this.matIconRegistry.addSvgIcon(
        "fsalpha",
        this.domSanitizer.bypassSecurityTrustResourceUrl(logoURL))
    }
  }
}

[JoostK]

@fireflysemantics that looks like an ordering issue, possibly related to the Webpack 5 update in the CLI (assuming you haven’t changed any other code). Injecting services into a module should still be possible in v12. In any way, this seems unrelated to this issue so please open a new one with a minimum reproduction.

[pkozlowski-opensource]

For example for the AssetService included by the original example here we need the HttpClient. If we start the application without having included the HttpClientModule the application fails to start. The compilation fails.

I see this use-case (or a variant of it) in the wild all the time. When I was thinking about this use-case I was leaning in the direction of creating a DI container without bootstrapping an app. Such DI container could have HttpClientModule, your AssetService and anything else needed to fetch data before bootstrapping an app. If we had such mechanism we wouldn’t need change anything about DI injection.