48 lines
1.8 KiB
TypeScript
48 lines
1.8 KiB
TypeScript
import { Injectable } from '@angular/core';
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import { HttpErrorResponse } from '@angular/common/http';
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import { Observable } from 'rxjs/Observable';
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import { of } from 'rxjs/observable/of';
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import { MessageService } from './message.service';
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/** Type of the handleError function returned by HttpErrorHandler.createHandleError */
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export type HandleError =
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<T> (operation?: string, result?: T) => (error: HttpErrorResponse) => Observable<T>;
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/** Handles HttpClient errors */
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@Injectable()
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export class HttpErrorHandler {
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constructor(private messageService: MessageService) { }
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/** Create curried handleError function that already knows the service name */
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createHandleError = (serviceName = '') => <T>
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(operation = 'operation', result = {} as T) => this.handleError(serviceName, operation, result);
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/**
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* Returns a function that handles Http operation failures.
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* This error handler lets the app continue to run as if no error occurred.
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* @param serviceName = name of the data service that attempted the operation
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* @param operation - name of the operation that failed
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* @param result - optional value to return as the observable result
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*/
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handleError<T> (serviceName = '', operation = 'operation', result = {} as T) {
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return (error: HttpErrorResponse): Observable<T> => {
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// TODO: send the error to remote logging infrastructure
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console.error(error); // log to console instead
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const message = (error.error instanceof ErrorEvent) ?
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error.error.message :
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`server returned code ${error.status} with body "${error.error}"`;
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// TODO: better job of transforming error for user consumption
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this.messageService.add(`${serviceName}: ${operation} failed: ${message}`);
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// Let the app keep running by returning a safe result.
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return of( result );
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};
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}
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}
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