The proper way to filter a backbone.collection by using Marionette.CompositeView

Question

I have a Marionette.CompositeView which needs to render a collection.
I would like to filter this collection on fetch and add action.
I tried with the following code (1) but I get the following error (2).

Any ideas, thanks.

---

(1)

var myCompositeView = Marionette.CompositeView.extend({

    initialize: function () {
        this.collection = app.taskCollection.where({type: 'todo'});
    }

});

(2)

// Uncaught TypeError: Object  has no method 'on'

Answer 1

Marionette's CompositeView and CollectionView both expect the collection setting to be a valid Backbone.Collection. The where method on Backbone's collection does not return a Backbone.Collection, it return an array. So you have to wrap a collection around the results:

initialize: function(){
  var filtered = app.taskCollection.where({type: 'todo'});
  this.collection = new Backbone.Collection(filtered);
}

Of course you can use any type that extends from Backbone.Collection. I just wanted to illustrate the point of it being a collection with this example.