In backbone marionette is there a way to tell if a view is already shown in a region?

it helps some times It should just be this.myRegion.currentView and model if bound to view: myRegion.currentView.model

With these it helps Solved after realizing this is from some peculiar coffeescript / Backbone / Marionette interactions...
I'm using tabs (not spaces) to indent my coffeescript, and I had:

<tab> class List.Layout extends App.Views.Layout
<space><space><tab> template: "admin/list/list_layout"

<tab> class List.Layout extends App.Views.Layout
<tab><tab> template: "admin/list/list_layout"

With these it helps I am writing my first Marionette app and would like to use the Marionette UI structure. , I've used following structure

-Marionette Application (root - have regions hash of existing node elements)
-- LayoutView (breaks application region in sub regions if needed)

---CollectionView || CompositeView (render collections)
----ItemView
||
---LayoutView (create more sub-regions) 
---- (other sub views)
||
---ItemView (render model)

var options = {
  something: "some value",
  another: "#some-selector"
};

MyApp.start(options);

MyApp.addRegions({
  someRegion: "#some-div",
  anotherRegion: "#another-div"
});

var MyRouter = new Marionette.AppRouter({
  controller: myController,
  appRoutes: {
    "foo": "doFoo",
    "bar/:id": "doBar"
  }
});

Backbone.Marionette.LayoutView.extend({
  template: "#layout-view-template",

  regions: {
    menu: "#menu",
    content: "#content"
  }
});

wish help you to fix your issue Looks like you're using Marionette 3.x. In short, you can use childViewEvents.
As to the specifics of your code, it would be better to have the childView of your CollectionView define the click event, as the listener to the child view event will receive the childView that was clicked. It would also be better to use the showChildView method in the ParentView's onRender.

const ChildView = marionette.View.extend({
    // ...
    triggers: {
        'click .bar': 'click:bar',
    },
    // or
    events: {
        'click .bar': 'clickBar'
    },
    clickBar() {
        // other child view stuff
        this.trigger('click:bar');
    },
});
const ChildCollectionView = marionette.View.extend({
    // ...
    childView: ChildView,
    childViewEvents: {
        'click:bar': 'barClicked',
    },
    barClicked(childView) {
        // other view stuff
        this.trigger('child:clicked:bar', childView);
        // or
        this.triggerMethod('child:clicked:bar', this, childView)
    }
});
const ParentView = marionette.View.extend({
    regions: {
        foo: '.foo'
    },
    childViewEvents: {
        'child:clicked:bar': 'clickBar'
    },
    clickBar(collectionChild, clickedChild) {
        console.log('click bar', collectionChild.cid, clickedChild.model.cid);
    },
    onRender() {
        this.showChildView('foo', new ChildCollectionView());
    }
});