How can I use/create dynamic template to compile dynamic Component with Angular 2.0?

Question

I want to dynamically create a template. This should be used to build a ComponentType at runtime and place (even replace) it somewhere inside of the ho

Answer 1

I decided to compact everything I learned into one file. There's a lot to take in here especially compared to before RC5. Note that this source file includes the AppModule and AppComponent.

import {
  Component, Input, ReflectiveInjector, ViewContainerRef, Compiler, NgModule, ModuleWithComponentFactories,
  OnInit, ViewChild
} from '@angular/core';
import {BrowserModule} from '@angular/platform-browser';

@Component({
  selector: 'app-dynamic',
  template: '<h4>Dynamic Components</h4><br>'
})
export class DynamicComponentRenderer implements OnInit {

  factory: ModuleWithComponentFactories<DynamicModule>;

  constructor(private vcRef: ViewContainerRef, private compiler: Compiler) { }

  ngOnInit() {
    if (!this.factory) {
      const dynamicComponents = {
        sayName1: {comp: SayNameComponent, inputs: {name: 'Andrew Wiles'}},
        sayAge1: {comp: SayAgeComponent, inputs: {age: 30}},
        sayName2: {comp: SayNameComponent, inputs: {name: 'Richard Taylor'}},
        sayAge2: {comp: SayAgeComponent, inputs: {age: 25}}};
      this.compiler.compileModuleAndAllComponentsAsync(DynamicModule)
        .then((moduleWithComponentFactories: ModuleWithComponentFactories<DynamicModule>) => {
          this.factory = moduleWithComponentFactories;
          Object.keys(dynamicComponents).forEach(k => {
            this.add(dynamicComponents[k]);
          })
        });
    }
  }

  addNewName(value: string) {
    this.add({comp: SayNameComponent, inputs: {name: value}})
  }

  addNewAge(value: number) {
    this.add({comp: SayAgeComponent, inputs: {age: value}})
  }

  add(comp: any) {
    const compFactory = this.factory.componentFactories.find(x => x.componentType === comp.comp);
    // If we don't want to hold a reference to the component type, we can also say: const compFactory = this.factory.componentFactories.find(x => x.selector === 'my-component-selector');
    const injector = ReflectiveInjector.fromResolvedProviders([], this.vcRef.parentInjector);
    const cmpRef = this.vcRef.createComponent(compFactory, this.vcRef.length, injector, []);
    Object.keys(comp.inputs).forEach(i => cmpRef.instance[i] = comp.inputs[i]);
  }
}

@Component({
  selector: 'app-age',
  template: '<div>My age is {{age}}!</div>'
})
class SayAgeComponent {
  @Input() public age: number;
};

@Component({
  selector: 'app-name',
  template: '<div>My name is {{name}}!</div>'
})
class SayNameComponent {
  @Input() public name: string;
};

@NgModule({
  imports: [BrowserModule],
  declarations: [SayAgeComponent, SayNameComponent]
})
class DynamicModule {}

@Component({
  selector: 'app-root',
  template: `
        <h3>{{message}}</h3>
        <app-dynamic #ad></app-dynamic>
        <br>
        <input #name type="text" placeholder="name">
        <button (click)="ad.addNewName(name.value)">Add Name</button>
        <br>
        <input #age type="number" placeholder="age">
        <button (click)="ad.addNewAge(age.value)">Add Age</button>
    `,
})
export class AppComponent {
  message = 'this is app component';
  @ViewChild(DynamicComponentRenderer) dcr;

}

@NgModule({
  imports: [BrowserModule],
  declarations: [AppComponent, DynamicComponentRenderer],
  bootstrap: [AppComponent]
})
export class AppModule {}`

Answer 2

2019 June answer

Great news! It seems that the @angular/cdk package now has first-class support for portals!

As of the time of writing, I didn't find the above official docs particularly helpful (particularly with regard to sending data into and receiving events from the dynamic components). In summary, you will need to:

Step 1) Update your AppModule

Import PortalModule from the @angular/cdk/portal package and register your dynamic component(s) inside entryComponents

@NgModule({
  declarations: [ ..., AppComponent, MyDynamicComponent, ... ]
  imports:      [ ..., PortalModule, ... ],
  entryComponents: [ ..., MyDynamicComponent, ... ]
})
export class AppModule { }

Step 2. Option A: If you do NOT need to pass data into and receive events from your dynamic components:

@Component({
  selector: 'my-app',
  template: `
    <button (click)="onClickAddChild()">Click to add child component</button>
    <ng-template [cdkPortalOutlet]="myPortal"></ng-template>
  `
})
export class AppComponent  {
  myPortal: ComponentPortal<any>;
  onClickAddChild() {
    this.myPortal = new ComponentPortal(MyDynamicComponent);
  }
}

@Component({
  selector: 'app-child',
  template: `<p>I am a child.</p>`
})
export class MyDynamicComponent{
}

See it in action

Step 2. Option B: If you DO need to pass data into and receive events from your dynamic components:

// A bit of boilerplate here. Recommend putting this function in a utils 
// file in order to keep your component code a little cleaner.
function createDomPortalHost(elRef: ElementRef, injector: Injector) {
  return new DomPortalHost(
    elRef.nativeElement,
    injector.get(ComponentFactoryResolver),
    injector.get(ApplicationRef),
    injector
  );
}

@Component({
  selector: 'my-app',
  template: `
    <button (click)="onClickAddChild()">Click to add random child component</button>
    <div #portalHost></div>
  `
})
export class AppComponent {

  portalHost: DomPortalHost;
  @ViewChild('portalHost') elRef: ElementRef;

  constructor(readonly injector: Injector) {
  }

  ngOnInit() {
    this.portalHost = createDomPortalHost(this.elRef, this.injector);
  }

  onClickAddChild() {
    const myPortal = new ComponentPortal(MyDynamicComponent);
    const componentRef = this.portalHost.attach(myPortal);
    setTimeout(() => componentRef.instance.myInput 
      = '> This is data passed from AppComponent <', 1000);
    // ... if we had an output called 'myOutput' in a child component, 
    // this is how we would receive events...
    // this.componentRef.instance.myOutput.subscribe(() => ...);
  }
}

@Component({
  selector: 'app-child',
  template: `<p>I am a child. <strong>{{myInput}}</strong></p>`
})
export class MyDynamicComponent {
  @Input() myInput = '';
}

See it in action

Answer 3

Following up on Radmin's excellent answer, there is a little tweak needed for everyone who is using angular-cli version 1.0.0-beta.22 and above.

COMPILER_PROVIDERScan no longer be imported (for details see angular-cli GitHub).

So the workaround there is to not use COMPILER_PROVIDERS and JitCompiler in the providers section at all, but use JitCompilerFactory from '@angular/compiler' instead like this inside the type builder class:

private compiler: Compiler = new JitCompilerFactory([{useDebug: false, useJit: true}]).createCompiler();

As you can see, it is not injectable and thus has no dependencies with the DI. This solution should also work for projects not using angular-cli.