Marionette.Backbone.js collection onRequest called for all instances

Question

I'm writing a Marionette layout with three similar sub-layouts. Every o them is an instance of the same class. Here's the code:

Marionette.Layout.extend({
        subCollection1: new SubCollection(),
        subCollection2: new SubCollection(),
        subCollection3: new SubCollection(),

        initialize: function () {
            this.subView1 = new subView ({
                collection: this.subCollection1)
            });
            this.subView2 = new subView ({
                collection: this.subCollection2)
            });
            this.subView1 = new subView ({
                collection: this.subCollection3)
            });
        },

        onRender: function() {
            this.Reg1.show(this.subView1);
            this.Reg2.show(this.subView2);
            this.Reg3.show(this.subView3);
        },

        fetchColletions: function () {
            this.subCollection1.fetch({ data: { /* some data for webserver */ } });
            this.subCollection2.fetch({ data: { /* some data for webserver */ } });
            this.subCollection3.fetch({ data: { /* some data for webserver */ } });
        }
});

Then in my subLayout I'm binding function to collection request in initialize function like this:

Marionette.Layout.extend({
        onCollectionRequest: function () {
            console.log('summary.onCollectionRequest ' + this.cid);
            //debugger;
        },

        initialize: function () {
            this.listenTo(this.collection, 'request', this.onCollectionRequest);

        }
    });

The problem is, calling fetch on any of those collections triggers request events in all three collections so I get log like this:

fetchcollections
GET /* Server url */ 200 OK 157ms
onCollectionRequest view15
onCollectionRequest view24
onCollectionRequest view33
GET /* Server url */ 200 OK 332ms
onCollectionRequest view15
onCollectionRequest view24
onCollectionRequest view33
/* And so on for the third one */

Am I missing something? I always thought that event binding is per instance not per class. How should I address this?

P.S. My code is additionally wrapped in require.js define() but I think it's irrelevant for my problem so I omitted it in code fragments.

Answer 1

Well, I've resolved my issue. It turns out I did a VERY bad thing in my App initializer. In order to have global fetch error handler I used 'on' function on prototype:

Backbone.Collection.prototype.on('error', fetchErrorHandler);

As also stated in How to add a default error handler to all Backbone models? it is a bad idea, beacause it creates global event handler for all collection instances in application. It causes every event handler is common for all collections which was excactly my issue.