In the angular2 application, there is a service named HttpClient. The purpose of this service is to include an authorization header in every request sent by the application to endpoints.
import { Injectable } from '@angular/core';
import { Headers, Http, Response, } from '@angular/http';
import { Router } from '@angular/router';
import { ErrorService } from '../../services/error/error.service'
@Injectable()
export class HttpClient {
private token: string;
private error: any;
private webApi = 'http://localhost:8080/api/v1/'; // Url to web api
constructor(
private http: Http,
private router: Router,
private errorService: ErrorService) { }
get(url: string): Promise<Response> {
return this.http.get(this.webApi + url, this.createAuthorizationHeader())
.toPromise()
.catch((e) => this.handleError(e));
}
post(url: string, data: any): Promise<Response> {
return this.http.post(this.webApi + url, JSON.stringify(data), this.createAuthorizationHeader())
.toPromise()
.catch((e) => this.handleError(e));
}
put(url: string): Promise<Response> {
return this.http.get(this.webApi + url, this.createAuthorizationHeader())
.toPromise()
.catch((e) => this.handleError(e));
}
delete(url: string): Promise<Response> {
return this.http.delete(this.webApi + url, this.createAuthorizationHeader())
.toPromise()
.catch((e) => this.handleError(e));
}
private handleError(error: any) {
var status: number = error.status;
if (status == 415) {
this.errorService.setError(error);
}
let errMsg = (error.message)
? error.message
: status
? `${status} - ${error.statusText}`
: 'Server error';
console.error(errMsg); // log to console instead
return Promise.reject(errMsg);
}
private createAuthorizationHeader() {
let headers = new Headers();
headers.append('Content-Type', 'application/json');
headers.append('Accept', 'application/json');
if (localStorage.getItem('token'))
this.token = localStorage.getItem('token');
headers.append('Authorization', 'Bearer ' + this.token);
return headers;
}
}
Additonally, the service sets errors through another custom service called ErrorService.
import { Injectable, EventEmitter } from '@angular/core';
@Injectable()
export class ErrorService {
error: any;
public errorAdded$: EventEmitter<any>;
constructor() {
this.errorAdded$ = new EventEmitter();
}
getError(): any {
return this.error;
}
setError(error: any) {
alert('is not going to be called');
this.error.error = error;
this.errorAdded$.emit(error);
}
}
These services will be initialized in the main.ts file.
...
import { ErrorService } from './services/error/error.service';
import { HttpClient } from './services/http/http.service';
...
bootstrap(AppComponent, [
appRouterProviders,
HTTP_PROVIDERS,
ErrorService,
HttpClient,
....
]);
The goal now is to present errors in the header component. Whenever an error occurs, it should be displayed in a separate box within the header.
A challenge faced is that the method ErrorService.setError(error) inside HttpClient.handleError does not trigger as expected.