How to subscribe to Observable of Component injected via @angular/cdk/portal?

Question

I\'m trying to implement a basic (very basic) modal implementation. I\'ve got a ModalService and a ModalComponent.

The ModalServic

Answer 1

This code works for me with very few changes, so I'm confused as to what your problem is. First I created a project with the Angular CLI using ng new. Then I installed ng material using the instructions on their site.

I created a modal service which is identical to yours:

    import {ApplicationRef, ComponentFactoryResolver, Injectable, Injector} from '@angular/core';
import {DomPortalHost, ComponentPortal} from "@angular/cdk/portal";
import {ModalComponent} from "./modal/modal.component";

@Injectable({
  providedIn: 'root'
})
export class ModalService {

  private modalPortal: ComponentPortal;
  private bodyPortalHost: DomPortalHost;

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

  showModal(modalName: string) {

    // set up the portal and portal host
    this.modalPortal = new ComponentPortal(ModalComponent);
    this.bodyPortalHost = new DomPortalHost(
      document.body,
      this.componentFactoryResolver,
      this.appRef,
      this.injector);

    // display the component in the page
    let componentRef = this.bodyPortalHost.attach(this.modalPortal);


    // listen for modal's close event
    componentRef.instance.onModalClose().subscribe(() => {
      console.log('I will be very happy if this this gets called, but it never ever does');
      this.closeModal();
    });

    // console.log(componentRef.instance.onModalClose()) shows 1 subscriber.
  }

  closeModal() {
    this.bodyPortalHost.detach();
  }
}

I created a modal component. The TypeScript is the same as yours:

import { Component, OnInit } from '@angular/core';
import {Observable, Subject} from "rxjs/index";

@Component({
  selector: 'app-modal',
  templateUrl: './modal.component.html',
  styleUrls: ['./modal.component.css']
})
export class ModalComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }

  private modalClose: Subject = new Subject();

  onModalClose(): Observable {
    return this.modalClose.asObservable();
  }

  closeModal() {
    // console.log(this.onModalClose()) **shows zero observers**   :-(
    this.modalClose.next();
    this.modalClose.complete();
  }

}

You didn't give us a model for the HTML, but this is what I used:

  modal works!

Close Modal

Here is my app.module.ts:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import {BrowserAnimationsModule} from '@angular/platform-browser/animations';

import { AppComponent } from './app.component';
import {ModalService} from "src/app/modal.service";
import { ModalComponent } from './modal/modal.component';

@NgModule({
  declarations: [
    AppComponent,
    ModalComponent
  ],
  imports: [
    BrowserModule,
    BrowserAnimationsModule
  ],
  providers: [ModalService],
  bootstrap: [AppComponent],
  entryComponents: [ModalComponent]
})
export class AppModule { }

Note I Defined the ModalComponent in the entryComponents and the ModalService as a provider.

The app.component HTML:

Show Modal

And the app.component typescript:

import { Component } from '@angular/core';
import {ModalService} from "./modal.service";
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'app';

  constructor(public modalService: ModalService){}

  showModal(){
       this.modalService.showModal("This is the modal name");
  }

}

I injected the ModalService into the constructor and called your showModal method in response to the button click in the main app.

Load the app:

Click the button and the modal shows up. It doesn't look like a modal, but that could be because of missing styling :

Now click the close button inside the modal:

You see the modal is gone and the console output displays your message.

Does this post help you find the tidbit you missed?

---

One thing to add. If you want to send data out of your modal to the component that called it, ust change your modalComponent's closeModal method:

  closeModal() {
    // console.log(this.onModalClose()) **shows zero observers**   :-(
    this.modalClose.next('Your Data Here, it can be an object if need be');
    this.modalClose.complete();
  }

And your modal service can access the data in the onModalClose().subscribe() method:

componentRef.instance.onModalClose().subscribe((results) => {
  console.log(results);
  console.log('I will be very happy if this this gets called, but it never ever does');
  this.closeModal();
});