Proper Error Handling in Angular HTTP Requests
Provide an example of how to handle errors in Angular HTTP requests using HttpErrorResponse.
import { HttpClient, HttpErrorResponse } from '@angular/common/http';
import { catchError } from 'rxjs/operators';
import { throwError } from 'rxjs';
@Injectable({
providedIn: 'root'
})
export class DataService {
constructor(private http: HttpClient) { }
getData() {
return this.http.get('/api/data')
.pipe(
catchError(this.handleError)
);
}
private handleError(error: HttpErrorResponse) {
if (error.error instanceof ErrorEvent) {
// A client-side or network error occurred. Handle it accordingly.
console.error('An error occurred:', error.error.message);
} else {
// The backend returned an unsuccessful response code.
// The response body may contain clues as to what went wrong.
console.error(
`Backend returned code ${error.status}, ` +
`body was: ${error.error}`
);
}
// Return an observable with a user-facing error message.
return throwError(
'Something bad happened; please try again later.'
);
}
}
This example demonstrates how to handle errors in Angular HTTP requests. It imports the necessary modules from Angular's HttpClient library and uses RxJS operators. A service named 'DataService' is created with a method 'getData()' to perform a GET request. If an error occurs, the catchError operator calls the 'handleError()' method. This method checks if the error is client-side or a server-side error and logs details appropriately. Then it returns an observable with a generic error message, using throwError, to be handled by the component invoking the request.