Cannot read property 'length' of undefined error when passing collection of models to a CollectionView in Marionette - backbone.js

Question

I am working in Backbone/Marionette and have a Collection, where I am parsing data, and creating a collection of models, which I then pass to a CollectionView, and a childView is set for that CollectionView.
The collection successfully makes it into the CollectionView, but it seems when my app attempts to display the childView, I get an Uncaught TypeError: Cannot read property 'length' of undefined
The error gets thrown in marionette here:
_filteredSortedModels: function(addedAt) {
var viewComparator = this.getViewComparator();
var models = this.collection.models;
addedAt = Math.min(Math.max(addedAt, 0), models.length - 1);
it appears as though "models" is undefined here.
My app is set up this way:
DrawerCollection:
App.module('Home.Drawer.Collections', function (Collections, App, Backbone, Marionette) {
model: App.Home.Drawer.Models.DrawerModel,
...make a request, parse some data...
responseData.push( new App.Home.Drawer.Models.DrawerModel({
...model properties...
});
var DrawerLayoutCollection = new App.Home.DrawerCollectionView({collection: responseData});
App.mainContainer.show(shelfLayoutCollection);
DrawerView:
App.module('Home', function(Home, App, Backbone, Marionette) {
Home.DrawerComponent = Backbone.Marionette.LayoutView.extend({
...my template, events, ui, etc....
});
});
Collection View (which has the DrawerView set to be its childView):
Home.DrawerCollectionView = Backbone.Marionette.CollectionView.extend({
childView: Home.DrawerComponent
});
Any input would be much appreciated!!!

Answer 1

Few things seem wrong with this line:
var DrawerLayoutCollection = new App.Home.DrawerCollectionView({collection: responseData});
First, DrawerLayoutCollection is not a constructor, but an instance.
Second, it's called a collection but it's actually a view instance.
You are passing responseData as a collection to the collection view instead of an actual backbone collection.
It should be something like
var drawerLayoutCollectionView = new App.Home.DrawerCollectionView({collection: new Backbone.Collection(responseData)});