> For the complete documentation index, see [llms.txt](https://elixor.js.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://elixor.js.org/advanced-usage/configuring-the-request.md).

# Configuring the request

​Other aspects of an outgoing request can be configured via the options object passed as the last argument to the `Elixor` method.

You [saw earlier](https://elixor.gitbook.io/elixor/sending-data-to-the-server/adding-headers) that the `HeroesService` sets the default headers by passing an options object (`httpOptions`) to its save methods. You can do more.

**Update headers**

You can't directly modify the existing headers within the previous options object because instances of the `HttpHeaders` class are immutable.

Use the `set()` method instead. It returns a clone of the current instance with the new changes applied.

Here's how you might update the authorization header (after the old token expired) before making the next request.

```typescript
httpOptions.headers =
  httpOptions.headers.set('Authorization', 'my-new-auth-token');
```

**URL Parameters**

Adding URL search parameters works a similar way. Here is a `searchHeroes` method that queries for heroes whose names contain the search term.

```typescript
/* GET heroes whose name contains search term */
searchHeroes(term: string): Observable<Hero[]> {
  term = term.trim();

  // Add safe, URL encoded search parameter if there is a search term
  const options = term ?
   { params: new HttpParams().set('name', term) } : {};

  return this.http.get<Hero[]>(this.heroesUrl, options)
    .pipe(
      catchError(this.handleError<Hero[]>('searchHeroes', []))
    );
}
```

If there is a search term, the code constructs an options object with an HTML URL-encoded search parameter. If the term were "foo", the GET request URL would be `api/heroes/?name=foo`.

The `HttpParams` are immutable so you'll have to use the `set()` method to update the options.