post-detail.page.ts

import { Component, OnInit } from "@angular/core";
import { ActivatedRoute, ParamMap } from "@angular/router";
import { Observable } from "rxjs";
import { switchMap } from "rxjs/operators";
import { PostsService } from "./../posts.service";

@Component({
  selector: "app-post-detail",
  templateUrl: "./post-detail.page.html",
  styleUrls: ["./post-detail.page.scss"]
})
export class PostDetailPage implements OnInit {
  constructor(private route: ActivatedRoute, private postSrvc: PostsService) {}
  post$: Observable<any>;
  ngOnInit() {
    this.post$ = this.route.paramMap.pipe(
      switchMap((params: ParamMap) => this.postSrvc.fetchPost(params.get("id")))
    );
  }
}