[Ionic v4] Bug: Viewchild not binding properly.

Bug Report

Ionic Info Run ionic info from a terminal/cmd prompt and paste the output below.

Ionic:

   ionic (Ionic CLI)          : 4.0.6
   Ionic Framework            : @ionic/angular 4.0.0-beta.2
   @angular-devkit/core       : 0.7.3
   @angular-devkit/schematics : 0.7.3
   @angular/cli               : 6.1.3
   @ionic/ng-toolkit          : 1.0.6
   @ionic/schematics-angular  : 1.0.4

Cordova:

   cordova (Cordova CLI) : 8.0.0
   Cordova Platforms     : android 7.0.0, ios 4.5.5

System:

   Android SDK Tools : 25.2.5
   ios-deploy        : 1.9.2
   ios-sim           : 6.1.2
   NodeJS            : v8.9.4 (/Users/dtaalbers/.nvm/versions/node/v8.9.4/bin/node)
   npm               : 5.6.0
   OS                : macOS High Sierra
   Xcode             : Xcode 9.4.1 Build version 9F2000

Environment:

   ANDROID_HOME : /usr/local/Cellar/android-sdk/24.4.1_1

Describe the Bug I can’t get a reference to the tabbar from my viewmodel with the ViewChild. It’s not undefined but I get a object without the events/properties described in the docs.

Related Code My view

<ion-tabs #tabs [tabbarHidden]="!isAuthenticated" color="primary">
    <ion-tab label="Home" icon="home" href="/tabs/(home:home)">
        <ion-router-outlet name="home"></ion-router-outlet>
    </ion-tab>
    <ion-tab label="workspace" icon="home" href="/tabs/(workspace:workspace)">
        <ion-router-outlet name="workspace"></ion-router-outlet>
    </ion-tab>
    <ion-tab label="login" icon="home" href="/tabs/(login:login)">
        <ion-router-outlet name="login"></ion-router-outlet>
    </ion-tab>
</ion-tabs>

My tabs viewmodel.

export class TabsPage implements OnInit, OnDestroy, AfterViewInit {

    @ViewChild('tabs') private tabs: Tabs;

    private isAuthenticated: boolean;
    private subscription: Subscription;

    constructor(
        private navController: NavController,
        private authService: AuthenticationService
    ) { }

    public async ngOnInit(): Promise<void> {
        this.isAuthenticated = await this.authService.isAuthenticated();
        console.log(this.tabs);
        this.subscription = this.tabs.ionChange.subscribe(async (x) => {
            this.isAuthenticated = await this.authService.isAuthenticated();
        });
    }

    public async ngAfterViewInit(): Promise<void> {
         console.log(this.tabs);
    }

    public async ngOnDestroy(): Promise<void> {
        this.subscription.unsubscribe();
    }
}

The only thing I am getting from the console.log(this.tabs) is this:

and of course the error

Error: Uncaught (in promise): TypeError: Cannot read property 'subscribe' of undefined
TypeError: Cannot read property 'subscribe' of undefined

Expected Behavior I expect the ViewChild binding the correct object with the correct methods and parameters. That way I can subscribe to the tab change events to show the tabbar when the user is authenticated.

[brandyscarney]

@dtaalbers Awesome, I’m glad that workaround works! We are looking into how we can remove the need for {read: Tabs} though.

That issue seems to be unrelated. I tested out ionChange using the following:

<ion-tabs #tabs (ionChange)="tabsChanged($event)">

and it is working. So it seems to only be the subscribe that isn’t working. It would be great if you could create a new issue. Please feel free to tag me in it. 🙂

[ionitron-bot[bot]]

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