Reloading ion menu when a user log in

There is a {{user_name}} variable in my app. component.ts and want to use it for displaying user name which i am getting from local storage after the user log in .
But this loads only at app start and want to reload it after user log in . I cant under stand how to reload it .
cause when i close and reopen app after log in it works fine and user name displayed . but at first it shows only hi not showing user name.

<ion-menu [content]="content" >
                HI! {{user_name}}
          <ion-list >
            <button menuClose ion-item *ngFor="let p of pages" (click)="openPage(p)">
            <button  menuClose ion-item (click)="logout()" >
              Log Out
      <!-- Disable swipe-to-go-back because it's poor UX to combine STGB with side menus -->
      <ion-nav [root]="rootPage" #content swipeBackEnabled="false"></ion-nav>

When your user logs in publish an event. Then place an event.subscribe where you wish to display the name.

Example Login:

constructor(public events: Events){}

login(userData) {'user:login', userData);

Example Read User:

constructor(public events: Events) {
    events.subscribe('user-login', (user) => {
        console.log('Welcome Back ', user);

thanks a lot it worked