Retry Request With Http Interceptor

HTTP interceptors are useful tools for dealing with network requests in web applications. One common scenario where an HTTP interceptor can come in handy is retrying failed requests. In this article, we'll explore how to implement a retry mechanism for failed HTTP requests using an HTTP interceptor in Angular.

When making HTTP requests in Angular, you may encounter situations where a request fails due to network issues, server problems, or other unforeseen circumstances. In such cases, automatically retrying the failed request can help improve the reliability of your application.

To implement a retry mechanism with an HTTP interceptor, we first need to create a new interceptor class. This class will be responsible for intercepting outgoing HTTP requests and handling any errors that occur during the request.

Let's start by creating a new Angular service that will act as our HTTP interceptor. In this service, we'll implement the logic for retrying failed HTTP requests. Here's a basic example of what the interceptor class might look like:

Typescript

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

@Injectable()
export class RetryInterceptor implements HttpInterceptor {

  intercept(request: HttpRequest, next: HttpHandler): Observable&lt;HttpEvent&gt; {
    return next.handle(request).pipe(
      retry(3),  // Retry the request up to 3 times
      catchError((error) =&gt; {
        // Handle the error here
        return throwError(error);
      })
    );
  }
}

In the above code snippet, we define an `RetryInterceptor` class that implements the `HttpInterceptor` interface provided by Angular. Inside the `intercept` method, we use the `retry` operator from RxJS to specify the number of times we want to retry the request in case of an error.

To make use of our custom HTTP interceptor in our Angular application, we need to provide it in the app module. This can be done by adding it to the `providers` array in the module metadata. Here's how you can do it:

Typescript

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
import { RetryInterceptor } from './retry.interceptor';

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

By providing the `RetryInterceptor` class as an HTTP interceptor in the app module, Angular will automatically apply the retry logic to all outgoing HTTP requests. The `multi: true` option allows multiple interceptors to be registered at the same time.

With this setup in place, any failed HTTP requests in your Angular application will be automatically retried up to 3 times, providing a more robust and reliable user experience.

In conclusion, implementing a retry mechanism for failed HTTP requests using an HTTP interceptor in Angular is a great way to improve the reliability of your web applications. By following the steps outlined in this article, you can easily enhance the error-handling capabilities of your Angular project.

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