如何知道动态创建的 Angular 组件何时可以在 DOM 中请求？

Question

I dynamically create an Angular component like this (code is simplified, there are some missing parts):

[...]

@ViewChild(MyDirective, { static: true }) myHost!: MyDirective;

constructor(
    private readonly compiler: Compiler,
    private readonly injector: Injector,
  ) {}

[...]

const myModule: typeof MyModule = (
      await import('../../../my/my.module')
    ).MyModule;

const moduleFactory: NgModuleFactory<MyModule> = await this.compiler.compileModuleAsync(
      myModule,
    );


const moduleReference: NgModuleRef<MyModule> = moduleFactory.create(this.injector);


const componentFactory: ComponentFactory<MyComponent> = moduleReference.instance.resolveComponent();
const componentReference: ComponentRef<MyComponent> = myHost.viewContainerReference.createComponent(
      componentFactory,
      undefined,
      moduleReference.injector,
    );

componentReference.instance.item = myItem;    
componentReference.instance.options = myOptions;

// Here I need to wait ~200ms for the component to be available to request in the DOM ... 
await timer(200).toPromise();

const myComponent: Element = document.querySelector('my-component');

// Then I use the component to generate an image with the library html-to-image
const dataUrl: string = await toSvg(myComponent);


return dataUrl;

I have to wait ~200ms for my component to be available in the DOM to request... otherwise it returns undefined. I have tried to implement ngAfterViewInit in MyComponent and then expose an observable so I can subscribe to it and THEN request it, but it stills returns undefined. MyComponent only has @Inputs and a template, nothing else. The template looks something like this:

<ng-container *ngIf="condition; else loading">
  <div prop="stuff | MyPipe">stuff</div>
</ng-container>

<ng-template #loading>
  stuff
</ng-template>

How can I know when the dynamically created component is available to request?

Answer 1

I don't know if I have understood your code properly as there are some missing pieces. I think MyDirective is your anchor directive. And the answer below is based on those assumptions that I have made based on my understanding of your code base.

You should be using ComponentFactoryResolver.resolveComponentFactory() to resolve ComponentFactory for each of the components.

const componentFactory = this.componentFactoryResolver.resolveComponentFactory("give component name here");

const viewContainerRef = this.directiveName.viewContainerRef; //the directive should inject viewContainerRef to access the view container of the parent component which will host the dynamic components
viewContainerRef.clear(); 

const componentRef = viewContainerRef.createComponent<DynamicComponent>(componentFactory);

Read more about this here https://angular.io/guide/dynamic-component-loader