angular - 可配置的 Angular 9 模块

Question

我想创建带有 IVY 和 AOT 的可配置 Angular 9 模块。

IVY and AOT on by default in current version of Angular:

npx @angular/cli@9.0.6 new ng-modules --style=scss --routing=false

在最简单的场景中，它必须提供一个按名称可配置的有状态服务:
计数器.module.ts

@Injectable()
export class CounterService {
  private counter = 0;
  shot() {
    return this.counter++;
  }
}

@NgModule()
export class CounterModule {
  static withConfig(name: string): ModuleWithProviders {
    return {
      ngModule: CounterModule,
      providers: [{
        provide: name,
        useClass: CounterService
      }]
    };
  }
}

app.module.ts

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    CounterModule.withConfig('main.CountService'),
    CounterModule.withConfig('integration.CountService'),
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

app.component.ts

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent {
  title = 'ng-modules-shots';
  constructor(
    @Inject('main.CountService') counter: CounterService,
  ) {
    this.title = '' + counter.shot();
  }

}

此时一切正常。但是如果我想在 CounterModule.withConfig 中添加任何逻辑:
计数器.module.ts

...
@NgModule()
export class CounterModule {
  static withConfig(name?: string): ModuleWithProviders {
    const counterProviderToken = name ? name : CounterService;
    return {
      ngModule: CounterModule,
      providers: [{
        provide: counterProviderToken,
        useClass: CounterService
      }]
    };
  }
}

我收到一个错误:

ERROR in src/app/app.module.ts:11:16 - error NG1010: Value at position 1 in the NgModule.imports of AppModule is not a reference: [object Object]

我能做些什么呢？以某种方式修复它？也许还有另一种制作可配置模块的方法？

Answer 1

当前存在一个约束，即函数中只有一条语句。因此，如果您想为其添加任何逻辑并保持 AOT 正常工作，则应将其放在此语句中。

...
@NgModule()
export class CounterModule {
  static withConfig(name?: string): ModuleWithProviders {
    return {
      ngModule: CounterModule,
      providers: [{
        provide: name ? name : CounterService,
        useClass: CounterService
      }]
    };
  }
}

但是，您可以使用函数在此模块中生成提供程序:

...
@NgModule()
export class CounterModule {
  static withConfig(name?: string): ModuleWithProviders {
    return {
      ngModule: CounterModule,
      providers: this.generateProviders(name)
    };
  }

  private static generateProviders(name?: string): Provider[] {
    const counterProviderToken = name ? name : CounterService;
    return [{
      provide: counterProviderToken,
      useClass: CounterService
    }]
  }
}