How can I intercept http errors with angular2?

Question

Is there an API similar to angular 1.x's Interceptor API?

I want to be able to add interceptors at application startup that will

• show the login dialog whenever a 401 status code is returned
• show a generic error message whenever a 5xx status code is returned

for every http request the application makes.

Answer 1

You can create your own HTTPConnection that handles error and inject it into the root app component at bootstrap time.

export class CustomHTTPConnection implements Connection
{
}

and then inject it while bootstrapping as follows

bootstrap([provider(Connection,{useClass:CustomHTTPConnection}]);

If you want do not want to provide a custom connection class, you can do it for each individual request as Http returns an observable which as 3 parameters: onNext, onError, onCompleted.

You can use it as follows:

class Component
{
constructor(private httpService:HttpService){
}
onInit(){
 this.httpService.getData().subscribe(
  ()=>{},  //on Next
  ()=>{}   //onError
}
}