Angular view not updating despite variables changed in model

user_10027183 0
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I'm making a youtube playlist project with Gooogle OAuth, I met a little issue while handling the authentication process, the variable isAuthorized is where I store the user sign-in state, I can see in the console that it's changed to true after user sign in, but it's still false in the View section. I wonder how exactly I solve this?

below is my code for the Model section

GoogleAuth: any;
user: any;
isAuthorized = false;

 ngOnInit(): void {
    // Load auth2 library
    gapi.load("client:auth2", this.initClient);
  }

  loadClient = () => {
    gapi.client.setApiKey(this.API_KEY);
    return gapi.client
      // same as "https://www.googleapis.com/discovery/v1/apis/youtube/v3/rest"
      .load("youtube", "v3")
      .then(
        () => {
          console.log("GAPI client loaded for API");
        },
        function (err) {
          console.error("Error loading GAPI client for API", err);
        }
      );
  }

  // Init API client library and set up sign in listeners
  initClient = () => {
    gapi.client
      .init({
        discoveryDocs: this.DISCOVERY_DOCS,
        clientId: this.CLIENT_ID,
        scope: this.SCOPES,
      })
      .then(() => {
        this.GoogleAuth = gapi.auth2.getAuthInstance();
        // Listen for sign-in state changes.
        this.GoogleAuth.isSignedIn.listen(this.handleSigninStatus);

        // Handle initial sign-in state. (Determine if user is already signed in.)
        this.handleSigninStatus();
        this.loadClient()
      });
  }

  handleSigninStatus = () => {
    this.user = this.GoogleAuth.currentUser.get();
    this.isAuthorized = this.user.hasGrantedScopes(this.SCOPES);
    if (this.isAuthorized) {
      this.loadClient()
      // this.getChannelInfo() //display playlist data
    } else {
      //do nothing
    }
  }

  // Handle login
  handleAuthClick = () => {
    this.GoogleAuth.signIn({ scope: this.SCOPES })
      .then(() => {
        console.log("Sign-in successful");
        // this.isLoggedIn = true
        this.getChannelInfo()
      },
        (err: any) => { console.error("Error signing in", { err }) });
  }

  // Handle logout
  handleSignoutClick = () => {
    this.GoogleAuth.signOut();
    this.GoogleAuth.disconnect();
    // gapi.auth2.getAuthInstance().signOut().then(() => { this.googleUser = null });
  }

and this is my HTML, aka the View section:

<mat-toolbar>
      <a href="/">My Application {{isAuthorized}}</a>
      <ng-template [ngIf]="isAuthorized" [ngIfElse]="loggedOut">
        <button mat-raised-button color="warn" id="signout-button" (click)="handleSignoutClick()">Log Out</button>
      </ng-template>
      <ng-template #loggedOut>
        <button mat-raised-button color="warn" id="authorize-button" (click)="handleAuthClick()">Log In</button>
      </ng-template>
    </mat-toolbar>

enter image description here

youtube-data-api angular google-oauth youtube-api model-view-controller
1 Answers

Because this.GoogleAuth events operate out of angular's scope/zone you need to bring its callbacks into the angular zone. This way angular's lifecycle events will handle the changes on the data appropriately.

Wrap your event handler function(s) with ngZone's run function. This is advisable every time you are modifying an angular monitored variable via events that do not belong to the angular scope/zone:

constructor(private ngZone: NgZone ... 

...

initClient = () => {
    gapi.client
      .init({
        discoveryDocs: this.DISCOVERY_DOCS,
        clientId: this.CLIENT_ID,
        scope: this.SCOPES,
      })
      .then(() => {
  this.ngZone.run(() => { // <-- here
        this.GoogleAuth = gapi.auth2.getAuthInstance();
        // Listen for sign-in state changes.
        this.GoogleAuth.isSignedIn.listen(this.handleSigninStatus);

        // Handle initial sign-in state. (Determine if user is already signed in.)
        this.handleSigninStatus();
        this.loadClient()
  });
      });
  }


handleSigninStatus = () => {
  this.ngZone.run(() => { // <-- here
    this.user = this.GoogleAuth.currentUser.get();
    this.isAuthorized = this.user.hasGrantedScopes(this.SCOPES);
    if (this.isAuthorized) {
      this.loadClient()
      // this.getChannelInfo() //display playlist data
    } else {
      //do nothing
    }
  });
}

The easiest way to bring model modifications into the angular's scope/zone is to wrap them with a ngZone call like this one above.

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