(Angularfire) Retrieve specific data from firebase database with id

Question

I'm trying to create a "blog" with angular and firebase. I'm doing fine for my first project with both Angular and Firebase.

I made the frontpage where all the entries are loaded and then added a "read more..." hyperlink to the route of the specific article plus the id of the entry. Here's the HTML:

<div style="background-color:white" class=" contenedorBlog">

    <h1 style="padding-top:100px;" class="text-center mb-4">Pizarrón</h1>

    <div *ngFor="let item of items" style="padding:40px" class="rounded">
      <h2> {{item.title}} </h2>
      <p>Date: {{ item.systemDate }}</p>
      <div class="content" [innerHTML]="item.content"></div>
      <a [routerLink]="['/article', item.id]">Read more...</a>
    </div>

  </div>

And here's the HTML of the article component:

<div style="background-color:white" class=" contenedorBlog">

    <div style="padding:40px" class="rounded">
      <h2> {{items.title}} </h2>
      <p>Fecha: {{ items.systemDate }}</p>
      <div class="content" [innerHTML]="items.content"></div>
    </div>

  </div>

I'm trying to figure out how can i call the specific object having the id on the route (article/:id).

this is what i have so far (article.component.ts)

export class ArticlesComponent implements OnInit {

   items:any;

   constructor(private blogService: UploadService, private route: ActivatedRoute) {
      this.route.params.subscribe(params=> {
      this.items=this.blogService.getObjectById(params['id']);
   });
   }

   ngOnInit() {
   }

}

Problem is... i don't know what to do next. I'm calling a function insde a service that i want to retrieve me ONLY the object that contains the id that's on the route.

getObjectById(id) {
    ///Help
}

Thank you very much and sorry for my not that great english.

Answer 1

Change:

this.items=this.blogService.getObjectById(params['id']);

to:

this.blogService.getObjectById(params['id']).subscribe( i => {
        this.items = i;
    })

Them in getObjectById(id) :

getObjectById(id) { 
     return this.afs.collection('collectionName').doc(id).valueChanges()
}

If you want just one time the value use ".take(1)" before the ".subscribe"

Also you need to put *ngIf="items" in the element where you display "items" if you don't want see the "undefined" error.