How to do HTTP Error Handling in Angular ? 054

 How to do HTTP Error Handling in Angular ?

There are several ways to handle HTTP errors in Angular, depending on your specific needs and preferences. Here are some common approaches:

1. Basic Error Handling with subscribe:

• In your subscribe method, include an error handler (second argument) to catch errors returned by the HttpClient.

• Within the error handler, you can log the error, display a user-friendly message, or take any other necessary actions.

TypeScript

this.http.get<any[]>('https://api.example.com/data')
  .subscribe(data => {
    this.data = data;
  }, error => {
    console.error('Error fetching data:', error);
    // Display user-friendly message or redirect to error page
  });

2. Using catchError Operator:

• Use the catchError operator from RxJS within your HTTP request chain.

• This operator allows you to transform the error into a new Observable, essentially replacing the error with a custom response.

TypeScript

this.http.get<any[]>('https://api.example.com/data')
  .pipe(
    catchError(error => {
      // Handle specific error codes or types
      if (error.status === 404) {
        return of({ message: 'Data not found' });
      } else {
        // Return a generic error message
        return throwError('An error occurred.');
      }
    })
  )
  .subscribe(data => {
    this.data = data;
  });

3. Global Error Handling with HttpInterceptor:

• Create an HttpInterceptor to intercept all HTTP requests and responses.

• Within the interceptor, you can inspect the response status code and handle errors globally.

• This approach is beneficial for centralizing error handling and displaying consistent messages throughout your application.

TypeScript

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

@Injectable()
export class ErrorInterceptor implements HttpInterceptor {
  intercept(
    req: HttpRequest<any>,
    next: HttpHandler
  ): Observable<HttpEvent<any>> {
    return next.handle(req).pipe(
      catchError((error: HttpErrorResponse) => {
        // Handle specific errors or display a global error message
        return throwError(error);
      })
    );
  }
}

Remember to register your ErrorInterceptor in your AppModule to use it globally.

Additional Tips:

• Log errors for debugging and potential analysis.

• Provide user-friendly error messages that explain the issue and suggest possible solutions.

• Consider retrying requests on specific error codes with exponential backoff for temporary network issues.

• Use a centralized error service to manage and report errors across your application.

By implementing effective HTTP error handling, you can create a more robust and user-friendly Angular application.

Sources

1. https://github.com/dcuesta1/auto

2. https://github.com/Sarthak123456/githubIssueReport

3. https://github.com/18cs/LodgeNET

4. https://ithelp.ithome.com.tw/m/articles/10207322