title: error TS2322: Type 'number' is not assignable to type 'string'
body: <p>I am trying to build an app, where I want to get my posts, at first, by user and then when a post is clicked, I want to get this particular post by id.</p>
  
  <p>And finally I get the following errors:</p>
  
  <blockquote>
    <p>ERROR in src/app/cars/car-detail/car-detail.component.ts(25,11): error
    TS2322: Type 'Observable&lt;{ _id: string; title: string; content:
    string; imagePath: string; creator: string; }>' is not assignable to
    type 'Car[]'.</p>
  </blockquote>
  
  <p>Property 'includes' is missing in type 'Observable&lt;{ _id: string; title: string; content: string; imagePath: string; creator: string; }>'.</p>
  
  <p>src/app/cars/car-detail/car-detail.component.ts(26,11): error TS2322: Type 'number' is not assignable to type 'string'.</p>
  
  <pre><code>import { Input, Component, OnInit } from '@angular/core';
  import { Car } from '../car.model';
  import { CarsService } from '../cars.service';
  import { ActivatedRoute, Params } from '@angular/router';
  
  
  @Component({
    selector: 'app-post-detail',
    templateUrl: './post-detail.component.html',
    styleUrls: ['./post-detail.component.css']
  })
  export class PostDetailComponent implements OnInit {
    @Input() post: Post[] = [];
    @Input() id: string;
    constructor(
      private postsService: PostsService,
      private route: ActivatedRoute
    ) { }
  
    ngOnInit() {
      this.route.params
        .subscribe(
          (params: Params) =&gt; {
            this.post = this.postsService.getPost(this.id);
            this.id = +params['id'];
          }
        );
    }
  
  }
  </code></pre>
  
  <p>What should I do?</p>