Angular - res.json() is not a function

Question

I am having an issue with my API Service. This service connects to my nodejs backend api.

The error says

ERROR TypeError: res.json is not a function

I am getting this error after recently updated this service to use the HTTPClient instead of Http. Im getting this reponse because im missing the old http with the new? if thats the case is there an new Response and how do i use it?

import { Injectable } from '@angular/core';
import { environment } from '../../environments/environment';
import { HttpHeaders, HttpClient, HttpParams } from '@angular/common/http';
import { Response } from '@angular/http';
import { Observable } from 'rxjs/Rx';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

import { JwtService } from './jwt.service';

@Injectable()
export class ApiService {
  constructor(
    private http: HttpClient,
    private jwtService: JwtService
  ) {}

  private setHeaders(): HttpHeaders {
    const headersConfig = {
      'Content-Type': 'application/json',
      'Accept': 'application/json'
    };
    if (this.jwtService.getToken()) {
      headersConfig['Authorization'] = this.jwtService.getToken();
    }
    return new HttpHeaders(headersConfig);
  }

  private formatErrors(error: any) {
     return Observable.throw(error.json());
  }

  get(path: string, httpParams: HttpParams = new HttpParams()): Observable<any> {
    return this.http.get(`${environment.api_url}${path}`, { headers: this.setHeaders(), params: httpParams })
    .catch(this.formatErrors)
    .map((res: Response) => res.json());
  }

  put(path: string, body: Object = {}): Observable<any> {
    return this.http.put(
      `${environment.api_url}${path}`,
      JSON.stringify(body),
      { headers: this.setHeaders() }
    )
    .catch(this.formatErrors)
    .map((res: Response) => res.json());
  }

  post(path: string, body: Object = {}): Observable<any> {
    return this.http.post(
      `${environment.api_url}${path}`,
      body,
      { headers: this.setHeaders() }
    )
    .catch(this.formatErrors)
    .map((res: Response) => res.json());
  }

  delete(path): Observable<any> {
    return this.http.delete(
      `${environment.api_url}${path}`,
      { headers: this.setHeaders() }
    )
    .catch(this.formatErrors)
    .map((res: Response) => res.json());
  }
}

Answer 1

HttpClient.get() applies res.json() automatically and returns Observable<HttpResponse<string>>. You no longer need to call this function yourself.

See Difference between HTTP and HTTPClient in angular 4?