Angular2 Dynamic Injection of Components at the Root

Question

Question

I am looking for the best approach for introducing a known / specific component to the root of the application and designing @Input()parameters on this component.

Demand

This is necessary to create things like modals / tooltips in the body of the application, so that overflow:hidden/ etc will not distort the position or completely disable it.

Study

I found that I can get ApplicationRef, and then hack it up and find it ViewContainerRef.

constructor(private applicationRef: ApplicationRef) {
}

getRootViewContainerRef(): ViewContainerRef {
  return this.applicationRef['_rootComponents'][0]['_hostElement'].vcRef;
}

as soon as I have, then I can call createComponentin the ref field:

appendNextToLocation<T>(componentClass: Type<T>, location: ViewContainerRef): ComponentRef<T> {
  const componentFactory = this.componentFactoryResolver.resolveComponentFactory(componentClass);
  const parentInjector = location.parentInjector;
  return location.createComponent(componentFactory, location.length, parentInjector);
}

, Input . , appendNextToLocation, :

const props = Object.getOwnPropertyNames(options);
for(const prop of props) {
  component.instance[prop] = options[prop];
}

, DI, , . :

let componentFactory = this.componentFactoryResolver.resolveComponentFactory(ComponentClass);
let parentInjector = location.parentInjector;

let providers = ReflectiveInjector.resolve([
  { provide: ComponentOptionsClass, useValue: options }
]);

childInjector = ReflectiveInjector.fromResolvedProviders(providers, parentInjector);

return location.createComponent(componentFactory, location.length, childInjector);

, , , . , , .

• https://github.com/angular/angular/issues/9293
• https://github.com/angular/angular/issues/6446

Answer 1

2.3.0 attachView, ApplicationRef, . , Angular2 -, , nativescript .., , / .

, Input .

import {
  ApplicationRef, ComponentFactoryResolver, ComponentRef, Injectable,
  Injector, ViewContainerRef, EmbeddedViewRef, Type
} from '@angular/core';

/**
 * Injection service is a helper to append components
 * dynamically to a known location in the DOM, most
 * noteably for dialogs/tooltips appending to body.
 * 
 * @export
 * @class InjectionService
 */
@Injectable()
export class InjectionService {
  private _container: ComponentRef<any>;

  constructor(
    private applicationRef: ApplicationRef,
    private componentFactoryResolver: ComponentFactoryResolver,
    private injector: Injector) {
  }

  /**
   * Gets the root view container to inject the component to.
   * 
   * @returns {ComponentRef<any>}
   * 
   * @memberOf InjectionService
   */
  getRootViewContainer(): ComponentRef<any> {
    if(this._container) return this._container;

    const rootComponents = this.applicationRef['_rootComponents'];
    if (rootComponents.length) return rootComponents[0];

    throw new Error('View Container not found! ngUpgrade needs to manually set this via setRootViewContainer.');
  }

  /**
   * Overrides the default root view container. This is useful for 
   * things like ngUpgrade that doesn't have a ApplicationRef root.
   * 
   * @param {any} container
   * 
   * @memberOf InjectionService
   */
  setRootViewContainer(container): void {
    this._container = container;
  }

  /**
   * Gets the html element for a component ref.
   * 
   * @param {ComponentRef<any>} componentRef
   * @returns {HTMLElement}
   * 
   * @memberOf InjectionService
   */
  getComponentRootNode(componentRef: ComponentRef<any>): HTMLElement {
    return (componentRef.hostView as EmbeddedViewRef<any>).rootNodes[0] as HTMLElement;
  }

  /**
   * Gets the root component container html element.
   * 
   * @returns {HTMLElement}
   * 
   * @memberOf InjectionService
   */
  getRootViewContainerNode(): HTMLElement {
    return this.getComponentRootNode(this.getRootViewContainer());
  }

  /**
   * Projects the inputs onto the component
   * 
   * @param {ComponentRef<any>} component
   * @param {*} options
   * @returns {ComponentRef<any>}
   * 
   * @memberOf InjectionService
   */
  projectComponentInputs(component: ComponentRef<any>, options: any): ComponentRef<any> {
    if(options) {
      const props = Object.getOwnPropertyNames(options);
      for(const prop of props) {
        component.instance[prop] = options[prop];
      }
    }

    return component;
  }

  /**
   * Appends a component to a adjacent location
   * 
   * @template T
   * @param {Type<T>} componentClass
   * @param {*} [options={}]
   * @param {Element} [location=this.getRootViewContainerNode()]
   * @returns {ComponentRef<any>}
   * 
   * @memberOf InjectionService
   */
  appendComponent<T>(
    componentClass: Type<T>, 
    options: any = {}, 
    location: Element = this.getRootViewContainerNode()): ComponentRef<any> {

    let componentFactory = this.componentFactoryResolver.resolveComponentFactory(componentClass);
    let componentRef = componentFactory.create(this.injector);
    let appRef: any = this.applicationRef;
    let componentRootNode = this.getComponentRootNode(componentRef);

    // project the options passed to the component instance
    this.projectComponentInputs(componentRef, options);

    appRef.attachView(componentRef.hostView);

    componentRef.onDestroy(() => {
      appRef.detachView(componentRef.hostView);
    });

    location.appendChild(componentRootNode);

    return componentRef;
  }
}

Answer 2

getRootViewContainer , getRootViewContainer , Angular. .

getRootViewContainer(): ComponentRef<any> {
    if(this._container) return this._container;

    return (this.applicationRef.components[0].hostView as EmbeddedViewRef<any>).rootNodes[0] as HTMLElement;
}