я получаю сообщение об ошибке при попытке отправить данные в файл json

Question

Что вызывает ошибку, которую я вижу в консоли?

zone-evergreen. js: 2828 POST http://localhost: 4200 / assets / data / hotel-details. json 404 (не найдено)

hotel-add-page.service.ts: 33 Внутренний код вернул код 404, тело было: handleError @ hotel-add-page.service.ts: 33

hotel-add.service.ts

@Injectable()
export class HotelAddServices {
    constructor(private http: HttpClient) { }
    private url = "assets/data/hotel-details.json";

    addHotelDetails(addHotel: IHotelView): Observable<IHotelView> {
            return this.http.post<IHotelView>(this.url, addHotel, {
                headers: new HttpHeaders({
                    'Content-Type': 'application/json'
                })
            })
                .pipe(catchError(this.handleError));
    }
    private handleError(error: HttpErrorResponse) {
        if (error.error instanceof ErrorEvent) {
            // A client-side or network error occurred. Handle it accordingly. 
            console.error('An error occurred:', error.error.message);
        }
}

hotel-add.component.ts

import { IHotelView } from './../hotel-view-page/hotel-view';
import { IHotelDetail } from './../hotel-home-page/hotel-details';
import { HotelAddServices } from './hotel-add-page.service';

@Component({
  selector: 'app-hotel-add-page',
  templateUrl: './hotel-add-page.component.html',
  styleUrls: ['./hotel-add-page.component.css']
})
export class HotelAddPageComponent implements OnInit {
  hotelAdd : IHotelView;
  private _url = "assets/data/hotel-details.json";

  constructor(private formBuilder: FormBuilder, private router: Router,private http: HttpClient, public _hotelAddService : HotelAddServices) { }

  addForm : FormGroup;

  ngOnInit(): void {
    this.addForm = this.formBuilder.group({
      id : [],
      hotelname : ['',Validators.required],
      hotellocation : ['',Validators.required],
      hotelrating : ['',Validators.required],
      hotelfacilities : ['',Validators.required],
      checkin : ['',Validators.required],
      checkout : ['',Validators.required],
      locationdes : ['',Validators.required],
      specialfeatures : ['',Validators.required],
      amenities : ['',Validators.required],
      hotelNearby : ['',Validators.required]
    });
  }

  saveHotel(): void{
    this._hotelAddService.addHotelDetails(this.hotelAdd).subscribe(
      (data : IHotelView) =>{
        console.log(data);
        this.router.navigate(['details']);
      }
    )
  }
}