Nativescript application-settings to persist a JSON value - json

Question

I'm new to nativescript and angular 2 development. Currently, in the application that i'm building, HTTP post returns a JSON object like
[
{
"firstname": "test",
"isauth": true,
"lastname": "client",
"roleid": 10,
"rolename": "",
"userid": 3507,
"username": ""
}
]
I'm required to somehow save the userid (returned by Backendservice.apiUrl) value from the above response in login.component.ts and use that to pass to another API (Backendservice.requesturl ) that I'll be calling from another component(invoked clientmaster.component.ts). How do I do this on {N} + angular2.
Can I use applicationsettings setstring to persist the userid value and use it when I make the next call?If that's possible how do I parse the JSON response from the observable and save the userid value ?
I know that I can use flatmap to make chained http requests. But I'm not quite sure about how to do it and i'm very new to angular 2 development and RxJs observable concepts.
Here's my code:
login.service.ts
login(user: User) {
let headers = new Headers();
//In the headers object, the Content-Type specifies that the body represents JSON.
headers.append("Content-Type", "application/json");
let urlSearchParams = new URLSearchParams();
urlSearchParams.append('username', user.username);
urlSearchParams.append('pwd', user.password);
let body = urlSearchParams.toString();
console.log("body"+body);
return this.http.post(
BackendService.apiUrl,
body,
{headers: headers })
.map((response ) => {
response.json();
// login successful if there's a jwt token in the response
console.log("RESPONSE: "+response.url);
console.log("response json "+response.status);
var body = response.json();
console.log("JSON BODY: ",JSON.stringify(body));
}
)
.catch(this.handleErrors);
}
getAssociatedRequest(){
let headers = new Headers();
//call made to the next URL
return this.http.get(
BackendService.requestUrl
)
.map((response: Response) => {
// login successful if there's a jwt token in the response
console.log("RESPONSE: ",response);
var body = response.json();
console.log("JSON BODY: ",JSON.stringify(body));
alert(JSON.stringify(body));}
)
.catch(this.handleErrors);
}
logoff() {
BackendService.token = "";
}
handleErrors(error: Response) {
console.log(JSON.stringify(error.json()));
return Observable.throw(error);
}
}
login.component.ts
import { Component, ElementRef, OnInit, ViewChild } from "#angular/core";
.....
.....
#Component({
selector: "vp-login",
moduleId: module.id,
providers: [LoginService],
templateUrl: "./login.component.html",
styleUrls: ["./login.component.css", "./login.css"],
})
export class LoginComponent implements OnInit {
user: User;
isAuthenticating = false;
constructor(private router: Router,
private loginService : LoginService,
private page: Page) {
this.user = new User();
}
ngOnInit() {
this.page.actionBarHidden = true;
}
login() {
if (getConnectionType() === connectionType.none) {
alert("Vessel-Pro requires an internet connection to log in.");
return;
}
try {
this.loginService.login(this.user)
.subscribe(
() => {
this.isAuthenticating = false;
this.router.navigate(["/clientMaster"]);
},
(error) => {
alert("Unfortunately we could not find your account.");
this.isAuthenticating = false;
}
);
} catch (error) {
console.log(error.message);
}
}
}
clientmaster.component.ts
import { Component, ElementRef, OnInit, ViewChild } from "#angular/core";
import { alert, LoginService, User } from "../shared";
...
#Component({
selector: "clientMaster",
moduleId: module.id,
templateUrl: './clientmaster.component.html',
styleUrls: ["./clientmaster.component.css"],
providers: [LoginService]
})
export class ClientMasterComponent implements OnInit{
isLoading = false;
constructor(private router: Router,
private LoginService: LoginService,
private page: Page) {}
ngOnInit(){
this.page.actionBarHidden = true;
}
/**
* gotoSRTPage
*/
public gotoSRTPage() {
this.router.navigate(["srtDetails"])
}
loadsrt(){
// alert("OK");
if (getConnectionType() === connectionType.none) {
alert("Oops!! looks like your device is not connected to the internet ");
return;
}
this.LoginService.getAssociatedRequest()
.subscribe(
(response) => {
console.log("Success Response" + response)
},
(error) => { console.log("Error happened", error.message)},
() => { console.log("srt is completed")
}
);