Adding a HTTP header to the Angular HttpClient doesn't send the header, why?

Question

Here is my code:

import { HttpClient, HttpErrorResponse, HttpHeaders } from '@angular/common/http';

---

logIn(username: string, password: string) {
    const url = 'http://server.com/index.php';
    const body = JSON.stringify({username: username,
                                 password: password});
    const headers = new HttpHeaders();
    headers.set('Content-Type', 'application/json; charset=utf-8');
    this.http.post(url, body, {headers: headers}).subscribe(
        (data) => {
            console.log(data);
        },
        (err: HttpErrorResponse) => {
            if (err.error instanceof Error) {
                console.log('Client-side error occured.');
            } else {
                console.log('Server-side error occured.');
            }
        }
    );
}

and here the network debug:

Request Method:POST
Status Code:200 OK
Accept:application/json, text/plain, */*
Accept-Encoding:gzip, deflate
Accept-Language:en-US,en;q=0.8
Cache-Control:no-cache
Connection:keep-alive
Content-Length:46
Content-Type:text/plain

and Data are stored in 'Request Payload' but in my server doesn't received the POST values:

print_r($_POST);
Array
(
)

I believe the error comes from the header not set during the POST, what did I do wrong?

Answer 1

The instances of the new HttpHeader class are immutable objects. Invoking class methods will return a new instance as result. So basically, you need to do the following:

let headers = new HttpHeaders();
headers = headers.set('Content-Type', 'application/json; charset=utf-8');

or

const headers = new HttpHeaders({'Content-Type':'application/json; charset=utf-8'});

Update: adding multiple headers

let headers = new HttpHeaders();
headers = headers.set('h1', 'v1').set('h2','v2');

or

const headers = new HttpHeaders({'h1':'v1','h2':'v2'});

Update: accept object map for HttpClient headers & params

Since 5.0.0-beta.6 is now possible to skip the creation of a HttpHeaders object an directly pass an object map as argument. So now its possible to do the following:

http.get('someurl',{
   headers: {'header1':'value1','header2':'value2'}
});