Disable back button on some of the views in ionic 4

Ionic Framework Ionic Angular
5

I had to do the subscription in the constructor method for the app to detect the subscription properly.

But since I had to enable the back button for child views and only disable the back button on the top parent view, I had to set a local boolean value according to whether I was in the parent view or not.

Here’s the solution that I did to make it work (in case somebody else might stumble upon this challenge):

private isCurrentView: boolean;
private displayWarning: boolean;

constructor(private platform: Platform) {
   this.subscriptions.add(
      this.platform.backButton.subscribeWithPriority(9999, (processNextHandler) => {
		if (this.isCurrentView) {
			this.displayWarning = true;
            // Or other stuff that you want to do to warn the user.
		} else {
			processNextHandler();
		}
	})
}

ionViewDidEnter() {
    this.isCurrentView = true;	
}

ionViewWillLeave() {
    this.isCurrentView = false;
}

I only execute the processNextHandler() if I am not in the parent view - this enables the native back button function.

I hope this would be helpful to others.

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