Using Angular’s Httpinterceptor for Global Api Request Handling

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Angular’s HttpInterceptor is a powerful feature that allows developers to handle all HTTP requests and responses globally within an application. This capability is especially useful for tasks such as adding authentication tokens, logging, error handling, and modifying requests or responses uniformly.

What is an HttpInterceptor?

An HttpInterceptor is a class that implements the HttpInterceptor interface provided by Angular. It intercepts outgoing HTTP requests and incoming responses, enabling centralized control over API communication.

Setting Up an HttpInterceptor

To create an interceptor, follow these steps:

  • Create a new service that implements HttpInterceptor.
  • Implement the intercept method to handle requests and responses.
  • Register the interceptor in the app module providers.

Example Implementation

Below is a simple example of an HttpInterceptor that adds an authorization token to each request:

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

@Injectable()
export class AuthInterceptor implements HttpInterceptor {
  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    const token = 'your-auth-token';
    const clonedRequest = request.clone({
      setHeaders: {
        Authorization: `Bearer ${token}`
      }
    });
    return next.handle(clonedRequest);
  }
}

Don’t forget to register this interceptor in your app module:

import { HTTP_INTERCEPTORS } from '@angular/common/http';

@NgModule({
  providers: [
    { provide: HTTP_INTERCEPTORS, useClass: AuthInterceptor, multi: true }
  ],
  // other properties
})
export class AppModule { }

Benefits of Using HttpInterceptor

  • Centralized API request handling.
  • Consistent addition of headers like tokens.
  • Global error handling.
  • Logging and debugging of API calls.

Using Angular’s HttpInterceptor simplifies managing API requests across your application, ensuring consistency and reducing repetitive code.