Angular 6：如何在进行 http 调用时将响应类型设置为文本

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));
}

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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);

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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'});
}

---

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'  });
}

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For me this way worked. Like requestOptions as object

 returnObservable(): Observable<any> {
    const headers = new HttpHeaders().set('Content-Type', 'text/plain; charset=utf-8');
    const requestOptions: Object = {
      headers: headers,
      responseType: 'text'
    }
    return this.http.get<any>(this.streamURL , requestOptions);
 }

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The default assumption of the HttpClient is 'json' responseType. If you want to change it to 'text', you should do it like so:

  public signIn(dto: UserCredentialsDto): Promise<string> {
    return this.http.post<string>(
      `${this.url}/userCredentials/signIn`, dto, { responseType: 'text' as 'json'}).toPromise();
  }

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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'});

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To fix the compiler error, remove the generic type argument from the post method call.

DO THIS

return this.http.post('example', postBody, {
  responseType: 'text'
});

NOT THIS

return this.http.post<any>('example', postBody, {
  responseType: 'text'
});

The error appears because the post method signature does not contain a generic type argument when responseType: 'text.

See the different method signatures below:

With responseType: 'json' (the default)

post<T>(url: string, body: any | null, options?: {
    ...
    responseType?: 'json';
    ...
}): Observable<T>;

With responseType: 'text'

post(url: string, body: any | null, options: {
    ...
    responseType: 'text';
    ...
}): Observable<string>;

Notice the generic type argument only exists for type 'json'. Remove it to fix the error.

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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;
  }
}

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