angular 2 - Injected service in http error handler

Question

I have a method handleError() like in the documentation https://angular.io/docs/ts/latest/guide/server-communication.html#!#error-handling

private handleErro         


        

Answer 1

Since you're passing the function directly, you don't have the this context of your class in there. A really easy and best practice way would be to use a lambda or "fat arrow function":

this.http.get(url, ApiRequest.ACCEPT_JSON)
    .map(res => ApiHelper.extractData(res))
    .catch(err => this.handleError(err));

---

A really good read on when to use lambdas: https://stackoverflow.com/a/23045200/1961059

Answer 2

this in handleError in your case is probably not what you think it is.

Try to do the following:

this.http.get(url,
              ApiRequest.ACCEPT_JSON)
              .map(ApiHelper.extractData) 
              .catch(this.handleError.bind(this)); // <-- add .bind(this)

Answer 3

Possible solution is also to assign your service to static variable of class

ClassToHandleError {
   private static loginService: LoginService;

   constructor(private loginService: LoginService) {
      ClassToHandleError.loginService = loginService;
   }

   private handleError(error: any) {
    console.error(error);
    console.log(ClassToHandleError.loginService); // here you can use static reference
    return Observable.throw(error);
   }
}

I know this is just workaround and rinukkusu provided definetely better solution then me. I used it until I get through this question. But maybe in some special case this will be valuable for somebody :) .