Previous request to then execute another request at the angle

Question

After the user is logged in to my application, all the requests he performs must first hit an API that will validate if the plan is in agreement.

Is there any way to standardize the requests so that always make this previous request and only then perform the requested request if the plan is in agreement? Or I need to file a requisition?

The Http injector would serve for this?

Thank you

Answer 1

You need to use an Httpinterceptor.

For that you create a service of this kind:

@Injector()
export class RequestInterceptorService implements HttpInterceptor {

    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

        // adiciona o token desta forma
        // neste exemplo o token, quando existe, está guardado na localstorage
        if (localStorage.getItem('accessToken')) {
            request = request.clone({
                setHeaders: {
                    Authorization: 'Bearer ' + localStorage.getItem('accessToken')
                }
            });
        }


         return next.handle(request).pipe(
            tap(
              event => { },
              error => {
                this.handleErrors(error);
              }
            ),
            finalize(() => { })
        );
    }

    private handleErrors(err: HttpErrorResponse) {
        let errorMessage: string;
        if (err.status === 0) {
            errorMessage = 'Sem ligação à internet';
        } else if (err.status === 401) { // O token expirou ou nem foi enviado. Fazer novamente autenticação. 
            this.router.navigate(['/login']);
        } else { // ocorreu outro erro. Mostrar mensagem ao utilizador
            errorMessage = err.error.message;
        }

        if(errorMessage) {
            // mostrar mensagem em modal, por exemplo
        }
    }
}

And you add the service to HTTP_INTERCEPTORS providers:

@NgModule({
    declarations: [
        // ...
    ],
    imports: [
        // ...
    ],
    providers: [
        {
            provide: HTTP_INTERCEPTORS,
            useClass: RequestInterceptorService,
            multi: true,
        }
    ],
})

export class AppModule { }