compilation - Compile dynamic HTML in Angular 4/5- something similar to $compile in Angular JS

Question

I wanted to receive an HTML data via service call to server(this is for sure. I cannot keep templates in local) and manipulate them internally on how to show it(either as a modal or full page). This HTML with Angular tags should be looped to a component and work together. At most kind of $compile in Angular JS.

I am developing the solution in Angular 5 and should be compatible with AOT compiler. I had referred several solutions and landed to confusion on the deprecated and updated solutions. Please help me. I believe your updated answer would help many other people as well.. Thank you so much in advance!

Answer 1

For rendering HTML on the fly, you need DomSanitizer. E.g. something like this:

<!-- template -->
<div [innerHTML]="htmlData"></div>

// component
import { Component } from '@angular/core';
import { DomSanitizer } from '@angular/platform-browser';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  htmlData: any;
  constructor(private sanitizer: DomSanitizer) {}

  ngOnInit() {
    this.htmlData= this.sanitizer.bypassSecurityTrustHtml('<div style="border: 1px solid red;"><h2>Safe Html</h2><span class="user-content">Server prepared this html block.</span></div>');
  }
}

Now, that's the gist of it. You obviously also need a loading mechanic. You might also want to include some data into this block - if it's simple data, it can be on the fly:

this.htmlData = this.sanitizer.bypassSecurityTrustHtml(`<div>${this.someValue}</div>`);

For more complex scenarios you might need to create a dynamic component.

Edit: an example of a component resolved dynamically. With this, you create a component on-the-fly from server-sent html.

@Component({
  selector: 'my-component',
  template: `<h2>Stuff bellow will get dynamically created and injected<h2>
          <div #vc></div>`
})
export class TaggedDescComponent {
  @ViewChild('vc', {read: ViewContainerRef}) vc: ViewContainerRef;

  private cmpRef: ComponentRef<any>;

  constructor(private compiler: Compiler,
              private injector: Injector,
              private moduleRef: NgModuleRef<any>,
              private backendService: backendService,
              ) {}

  ngAfterViewInit() {
    // Here, get your HTML from backend.
    this.backendService.getHTMLFromServer()
        .subscribe(rawHTML => this.createComponentFromRaw(rawHTML));
  }

  // Here we create the component.
  private createComponentFromRaw(template: string) {
    // Let's say your template looks like `<h2><some-component [data]="data"></some-component>`
    // As you see, it has an (existing) angular component `some-component` and it injects it [data]

    // Now we create a new component. It has that template, and we can even give it data.
    const tmpCmp = Component({ template, styles })(class {
      // the class is anonymous. But it's a quite regular angular class. You could add @Inputs,
      // @Outputs, inject stuff etc.
      data: { some: 'data'};
      ngOnInit() { /* do stuff here in the dynamic component */}
    });

    // Now, also create a dynamic module.
    const tmpModule = NgModule({
      imports: [RouterModule],
      declarations: [tmpCmp],
      // providers: [] - e.g. if your dynamic component needs any service, provide it here.
    })(class {});

    // Now compile this module and component, and inject it into that #vc in your current component template.
    this.compiler.compileModuleAndAllComponentsAsync(tmpModule)
      .then((factories) => {
        const f = factories.componentFactories[0];
        this.cmpRef = f.create(this.injector, [], null, this.moduleRef);
        this.cmpRef.instance.name = 'my-dynamic-component';
        this.vc.insert(this.cmpRef.hostView);
      });
  }

  // Cleanup properly. You can add more cleanup-related stuff here.
  ngOnDestroy() {
    if(this.cmpRef) {
      this.cmpRef.destroy();
    }
  }
}