Response Interceptor in Angular2

Question

I send many HTTP requests into a server, and the server returns each of them a response with a new access token (maybe in header or body).

Is there any way to handle all responses before or after it finishes, like middleware for a request in some back-end framework?

Rahul Singh · Answer 1 · 2018-01-12T17:26:51.063

If you are using Angular version 4+ you can look at HttpClientModule which provides support for interceptors.

eg

import { Observable } from 'rxjs';
import {Injectable} from '@angular/core';
import {HttpEvent, HttpInterceptor, HttpHandler, HttpRequest} from '@angular/common/http';
import { HttpErrorResponse } from "@angular/common/http";

@Injectable()
export class AngularInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next.handle(req).do(event => {}, err => {
        if(err instanceof HttpErrorResponse){
            console.log("Error Caught By Interceptor");
            //Observable.throw(err);
        }
    });
  }
}

Register to app.module

@NgModule({
    declarations: [
        AppComponent
    ],
    imports: [
        BrowserModule,
        HttpClientModule
    ],
    providers: [
        [ { provide: HTTP_INTERCEPTORS, useClass: 
              AngularInterceptor, multi: true } ]
    ],
    bootstrap: [AppComponent]
})
export class AppModule {
}

Response Interceptor in Angular2

2 Answers2