Angular - Set headers for every request

Question

I need to set some Authorization headers after the user has logged in, for every subsequent request.

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To set headers for a particular request,

Answer 1

After some investigation, I found the final and the most easy way is to extend BaseRequestOptions which I prefer.
The following are the ways I tried and give up for some reason:
1. extend BaseRequestOptions, and add dynamic headers in constructor(). It can not work if I login. It will be created once. So it is not dynamic.
2. extend Http. Same reason as above, I can not add dynamic headers in constructor(). And if I rewrite request(..) method, and set headers, like this:

request(url: string|Request, options?: RequestOptionsArgs): Observable {
 let token = localStorage.getItem(AppConstants.tokenName);
 if (typeof url === 'string') { // meaning we have to add the token to the options, not in url
  if (!options) {
    options = new RequestOptions({});
  }
  options.headers.set('Authorization', 'token_value');
 } else {
  url.headers.set('Authorization', 'token_value');
 }
 return super.request(url, options).catch(this.catchAuthError(this));
}

You just need to overwrite this method, but not every get/post/put methods.

3.And my preferred solution is extend BaseRequestOptions and overwrite merge() :

@Injectable()
export class AuthRequestOptions extends BaseRequestOptions {

 merge(options?: RequestOptionsArgs): RequestOptions {
  var newOptions = super.merge(options);
  let token = localStorage.getItem(AppConstants.tokenName);
  newOptions.headers.set(AppConstants.authHeaderName, token);
  return newOptions;
 }
}

this merge() function will be called for every request.