Angular HttpClient append headers to HttpHeaders [duplicate]

Question

I am upgrading from the HttpServer to the HttpClientService and as part of that I have to switch my headers from Headers to HttpHeaders. However For some reason my custom headers are no longer being appended. What do I need to update to have the headers appended?

  private getHeaders(headers?: HttpHeaders): HttpHeaders {     if (!headers) {       headers = new HttpHeaders();     }     headers.delete('authorization');     const token: any = this.storageService.getItem('token');     if (token) {       headers.append('Authorization', 'Bearer ' + token);     }     const user: User = this.storageService.getObject('user');     if (user && Object.keys(user).length) {       headers.append('X-Session-ID', user.uuid);       headers.append('X-Correlation-ID', this.uuidService.generateUuid());     }     return headers;   } 

That method returns a httpHeader but it's empty.

Answer 1

HttpHeaders.append returns a clone of the headers with the value appened, it does not update the object. You need to set the returned value to the headers.

angular/packages/common/http/src/headers.ts

append(name: string, value: string|string[]): HttpHeaders {    return this.clone({name, value, op: 'a'});  }  

So to append the headers you do this.

let headers: HttpHeaders = new HttpHeaders(); headers = headers.append('Content-Type', 'application/json'); headers = headers.append('x-corralation-id', '12345'); 

and boom!