Angular 6: How to set response type as text while making http call

Question

I trying to make http request to the spring rest API.. API returns a string value ("success" or "fail")... but I dont know how to set the response type as string value while making call to the API..its throwing error as Backend returned code 200, body was: [object Object]

My angular code is like below,

order.service.ts

import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { ProductSearch } from '../_models/product-search';
import { ProductView } from '../_models/product-view';
import { Observable } from 'rxjs';
import { catchError } from 'rxjs/operators';
import { ErrorHandlerService } from './error-handler.service';
import { Category } from '../_models/category';


@Injectable({
  providedIn: 'root'
})
export class OrderService {

  constructor(private http: HttpClient, private errorHandlerService: ErrorHandlerService) { }

addToCart(productId: number, quantity: number): Observable<any> {
    const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');
    console.log("--------order.service.ts----------addToCart()-------productId:"+productId+":------quantity:"+quantity);
     return this.http.post<any>('http://localhost:8080/order/addtocart', 
              { dealerId: 13, createdBy: "-1", productId: productId, quantity: quantity}, 
              {headers: headers})
              .pipe(catchError(this.errorHandlerService.handleError));
    }
}

error-handler.service.ts

import { Injectable } from '@angular/core';
import { HttpErrorResponse, HttpResponse } from '@angular/common/http';

import { Observable, throwError } from 'rxjs';
import { catchError, retry } from 'rxjs/operators';

@Injectable({
  providedIn: 'root'
})
export class ErrorHandlerService {

  constructor() { }

  public 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);
    } else {
      // The backend returned an unsuccessful response code.
      // The response body may contain clues as to what went wrong,
      console.error(
        `Backend returned code ${error.status}, ` +
        `body was: ${error.error}`);
    }
    // return an observable with a user-facing error message
    return throwError(
      'Something bad happened; please try again later.');
  };

}

Any help would be appreciated... thanks in advance..

Answer 1

To get rid of error:

Type '"text"' is not assignable to type '"json"'.

Read the Angular HTTP guide and use

responseType: 'text' as const

import { HttpClient, HttpHeaders } from '@angular/common/http';
.....
 return this.http
        .post<string>(
            this.baseUrl + '/Tickets/getTicket',
            JSON.stringify(value),
        { headers, responseType: 'text' as const }
        )
        .map(res => {
            return res;
        })
        .catch(this.handleError);

Answer 2

You should not use those headers, the headers determine what kind of type you are sending, and you are clearly sending an object, which means, JSON.

Instead you should set the option responseType to text:

addToCart(productId: number, quantity: number): Observable<any> {
  const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');

  return this.http.post(
    'http://localhost:8080/order/addtocart', 
    { dealerId: 13, createdBy: "-1", productId, quantity }, 
    { headers, responseType: 'text'}
  ).pipe(catchError(this.errorHandlerService.handleError));
}

Answer 3

On your backEnd, you should add:

@RequestMapping(value="/blabla",  produces="text/plain" , method = RequestMethod.GET)

On the frontEnd (Service):

methodBlabla() 
{
  const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');
  return this.http.get(this.url,{ headers, responseType: 'text'});
}

Answer 4

Use like below:

yourFunc(input: any):Observable<string> {
 var requestHeader = { headers: new HttpHeaders({ 'Content-Type': 'text/plain', 'No-Auth': 'False' })};
 const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');
 return this.http.post<string>(this.yourBaseApi+ '/do-api', input, { headers, responseType: 'text' as 'json'  });
}

Answer 5

Have you tried not setting the responseType and just type casting the response?

This is what worked for me:

/**
 * Client for consuming recordings HTTP API endpoint.
 */
@Injectable({
  providedIn: 'root'
})
export class DownloadUrlClientService {
  private _log = Log.create('DownloadUrlClientService');


  constructor(
    private _http: HttpClient,
  ) {}

  private async _getUrl(url: string): Promise<string> {
    const httpOptions = {headers: new HttpHeaders({'auth': 'false'})};
    // const httpOptions = {headers: new HttpHeaders({'auth': 'false'}), responseType: 'text'};
    const res = await (this._http.get(url, httpOptions) as Observable<string>).toPromise();
    // const res = await (this._http.get(url, httpOptions)).toPromise();
    return res;
  }
}

Answer 6

By Default angular return responseType as Json, but we can configure below types according to your requirement.

responseType: 'arraybuffer'|'blob'|'json'|'text'

Ex:

this.http.post(
    'http://localhost:8080/order/addtocart', 
    { dealerId: 13, createdBy: "-1", productId, quantity }, 
    { headers, responseType: 'text'});