CODEWITHSUNDEEP
javascriptdependency-injectiontypescriptangularsharedservices
Sloth Armstrong
Sloth Armstrong

Reputation: 1066

Why is my shared service not updating across my components?

In my Angular2 app I am bootstrapping an auth service LocalStorage that I want shared across my components:

bootstrap(AppComponent, [
    ROUTER_PROVIDERS,
    LocalStorage
]);

LocalStorage is defined as follows:

import {JwtHelper} from 'angular2-jwt/angular2-jwt';
import { Injectable } from 'angular2/core';

@Injectable()
export class LocalStorage {

    key:string = 'jwt';
    jwtHelper:JwtHelper = new JwtHelper();
    username:string;

    constructor() {

        let token = localStorage.getItem(this.key);

        if (token == null) return;

        if (this.jwtHelper.isTokenExpired(token)) {
            localStorage.removeItem(this.key);
        } else {
            this.username = this.jwtHelper.decodeToken(token).username;
        }
    }

    login(jwt:string) {
        localStorage.setItem(this.key, jwt);
    }

    logout() {
        localStorage.removeItem(this.key);
    }

    isLoggedIn():boolean {
        return this.username != null;
    }

    getUsername():string {
        return this.username;
    }

    getToken():string {
        return localStorage.getItem(this.key);
    }
}

The problem is, however, when I share and update it across components only the component that updates it recognizes the changes. It is injected into components and edited like this:

    constructor(private router:Router, private localStorage:LocalStorage) {

        ...
    }

    logout(event) {
        event.preventDefault();
        this.localStorage.logout();
        this.router.navigateByUrl(RoutingPaths.home.path);
    }

Why is it that it seems multiple instances of this service are being created across components? Thanks.

Edit An example of a component template binding is:

Component:

import {Component} from 'angular2/core';
import {Router, RouteConfig, ROUTER_DIRECTIVES} from 'angular2/router';
import {RoutingPaths} from './routing-paths';
import {LoggedInOutlet} from './logged-in-outlet';
import {LocalStorage} from './local-storage'

@Component({
    selector: 'my-app',
    templateUrl: 'app/app.template.html',
    directives: [LoggedInOutlet, ROUTER_DIRECTIVES]
})
export class AppComponent {

    registerName:string;

    constructor(private router:Router, private localStorage:LocalStorage) {
        this.registerName = RoutingPaths.register.name;
    }

    logout(event) {
        event.preventDefault();
        this.localStorage.logout();
        this.router.navigateByUrl(RoutingPaths.home.path);
    }
}

Template:

<a *ngIf="!localStorage.isLoggedIn()" [routerLink]="[registerName]">Register</a>

Final Edit

Well this is embarrassing, after actually editing the username in the service it now works:

    login(jwt:string) {
        localStorage.setItem(this.key, jwt);
        this.username = this.jwtHelper.decodeToken(jwt).username;  // here
    }

    logout() {
        localStorage.removeItem(this.key);
        this.username = null; // here
    }

Sorry for wasting everyone's time. Thanks again.

Upvotes: 0

Views: 279

Answers (3)

igorzg
igorzg

Reputation: 1506

It's because you assigned LocalStorage as provider somewhere in your code.

Check if any of your component is containing:

@Component({
    providers: [LocalStorage]
})

This gives an Injector instruction to create a new Instance for that component and all children if child one again does not have an provided LocalStorage itself.

Upvotes: 1

Sloth Armstrong
Sloth Armstrong

Reputation: 1066

I forgot to actually modify username in the service itself:

    login(jwt:string) {
        localStorage.setItem(this.key, jwt);
        this.username = this.jwtHelper.decodeToken(jwt).username;  // here
    }

    logout() {
        localStorage.removeItem(this.key);
        this.username = null; // here
    }

Upvotes: 0

basarat
basarat

Reputation: 276269

The problem is, however, when I share and update it across components only the component that updates it recognizes the changes

This is because of angular 2 component model is a Tree:

enter image description here

So only the component that changes and its sub components are rerendered. For stuff like singletons containing state used across components you need something like redux : https://medium.com/google-developer-experts/angular-2-introduction-to-redux-1cf18af27e6e#.yk11zfcwz

Upvotes: 0

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