Navigate to another route from a service - nativescript

Question

I have service that intercepts all my Http requests so I can check if the user's token is valid or not. When a Http response is 401, I want the current user to be logged out of the application:
import { Http, ConnectionBackend, RequestOptions, RequestOptionsArgs, Request, Response } from '#angular/http'
import { Router } from '#angular/router'
import { Observable } from 'rxjs/Observable'
import { Injectable } from '#angular/core'
import { Config } from './shared/config'
import { RouterExtensions } from 'nativescript-angular/router'
import 'rxjs/add/observable/throw'
#Injectable()
export class RequestInterceptorService extends Http {
private config: Config = new Config()
constructor(
backend: ConnectionBackend,
defaultOptions: RequestOptions,
private router: Router,
private routerExtensions: RouterExtensions,
) {
super(backend, defaultOptions)
}
request(url: string | Request, options?: RequestOptionsArgs): Observable<Response> {
return this.intercept(super.request(url, options))
}
intercept(observable: Observable<Response>): Observable<Response> {
return observable.catch((err, source) => {
if (err.status === 401) {
this.logout()
return Observable.empty()
} else {
return Observable.throw(err)
}
})
}
logout() {
this.config.clear()
this.routerExtensions.navigate(["/signin"], {
clearHistory: true
})
}
}
My issue is that router or routerExtensions are always undefined, so I can't really redirect the user to any other path at all using this service.

Answer 1

So, I found the solution. It was just a mater of understanding all of what I was doing.
I created a RequestInterceptor service that extends Http module. It includes a interceptor that checks if the status code is equal to 401. In order to make it compatible with my project, I decided to provide it as custom implementation of Http. The following code on my #NgModule does just that:
providers: [
{
provide: Http,
useClass: RequestInterceptorService
}
]
But the thing RequestInterceptorService does not have access to Http dependencies: ConnectionBackend and RequestOptions, so I had to inject them using the deps property, which is an array where I can identify an array of dependencies that will get injected. In my case, I need to inject not only the dependencies that Http requires (XHRBackend, RequestOptions), but also the one that my service will use: RouterExtensions.
My providers declaration looks like this:
providers: [
{
provide: Http,
useClass: RequestInterceptorService,
deps: [XHRBackend, RequestOptions, RouterExtensions]
}
]
After doing this, I was able to successfully redirect a user to the login page when a 401 status code is returned from any request.