Angular v6 pipe(map()) issue

Question

I would appreciate if someone could shed some light on this. I have been at it for days now.

Here is two functions that lives in my auth service. The login function that retrieves a valid jwt and then the refresh function that fetches a refreshed jwt.

LOGIN

  login(username: string, password: string): Observable<any> {
    const headers = new HttpHeaders().set('Authorization', `Basic ${environment.WSO2_AUTH_BASIC}`);
    const params = new HttpParams({
    fromObject: {
     grant_type: 'password',
     scope: 'openid',
     username: username,
     password: password
   }
 });

  return this.http.request<Token>('POST', environment.API_HOST + '/token', {
    headers: headers,
    body: params
  }).pipe(map(this._mapTokenResponse));
}

REFRESH

  private _refreshToken() {
const headers = new HttpHeaders().set('Authorization', `Basic ${environment.WSO2_AUTH_BASIC}`);
this.token = this.getToken();
const params = new HttpParams({
  fromObject: {
    grant_type: 'refresh_token',
    scope: 'openid',
    refresh_token: this.token.refresh_token
  }
});
return this.http.request<Token>('POST', environment.API_HOST + '/token', {
  headers: headers,
  params: params
}).pipe(map(this._mapTokenResponse, this));
}

I have created a separate arrow function that handles the mapping for both.

private _mapTokenResponse = (token: Token) => {
// login successful if there's a jwt token in the response
if (token && token.access_token) {
  // store user details and jwt token in local storage to keep user logged in between page refreshes
  token.id_token_data = this.jwtHelper.decodeToken(token.id_token);
  this._setSession(token);
}
return token;

}

I want this so that I do not duplicate code. The login function works perfectly but the refresh token returns this error:

ERROR Error: "Uncaught (in promise): TypeError: argument is not a function. Are you looking for `mapTo()`?

I have imported map from 'rxjs/operators'

Answer 1

Either you can do:

  return this.http.request<Token>('POST', environment.API_HOST + '/token', {
    headers: headers,
    body: params
  }).pipe(
    map(this._mapTokenResponse.bind(this))
  );

We use .bind(this) to set up the scope (the "this") of the function call. Otherwhise, you'll get an error each time you call this. in your callback function.

Or:

  return this.http.request<Token>('POST', environment.API_HOST + '/token', {
    headers: headers,
    body: params
  }).pipe(
    map((token: Token) => this._mapTokenResponse(token))
  );

This solution is much cleaner in my opinion.