Show Backbone Collection element in a Marionette region - layout

Question

I have a Backbone application running and working properly with requirejs. Now, I'm trying to make a migration to Marionette in order to have the code better organized.
I just want to show a model from a collection in a region, with two buttons in another region. I want to go to the next or previous model from that collection. And change its view on the model region.
But I don't know how to iterate over the collection and send its model to the view.
jsfiddle with some simplified code with this situation.
html:
<div class="player"></div>
<script id="layout-template" type="text/template">
<div class="modelView"></div>
<div class="controls"></div>
</script>
<script id="model-region" type="text/template">
<%=name%>
</script>
<script id="control-region" type="text/template">
<button id="prev">Prev</button>
<button id="next">Next</button>
</script>

Answer 1

If I understand your question, you are trying to coordinate events between two views on the same layout. In this case I would recommend setting up a Controller.
Then you can register view triggers for on your controls view:
ControlsView = Backbone.Marionette.ItemView.extend({
// ...
triggers: {
"click #previous": "control:previous",
"click #next": "control:next"
}
});
An then in your controller you would instantiate your views and setup a handler for the controlView triggers to update the modelView.
var Router = Marionette.AppRouter.extend({
appRoutes: {
"/": "start",
"/:index" : "showModel"
},
});
var Controller = Marionette.Controller.extend({
initialize: function(){
var self = this;
this.controlsView = new ControlsView();
this.modelView = new MainView();
this.myCollection = new MyCollection();
this.myIndex = 0;
this.myCollection.fetch().then(function(){
self.myIndex = 0;
});
this._registerTriggers();
},
start: function(){
this.controlLayout.show(this.controlView);
this.showModel();
},
showModel: function(index){
index = index || this.index;
this.modelView.model = myCollection.at(this.index);
this.modelLayout.show(this.modelView);
},
showNext: function(){
var max = this.myCollection.models.length;
this.index = max ? 1 : this.index + 1;
this.showModel();
},
showPrevious: function(){
var max = this.myCollection.models.length;
this.index = 0 ? max : this.index - 1;
this.showModel();
},
_registerTriggers: function(){
this.controlsView.on("control:next", this.showNext());
this.controlsView.on("control:previous", this.showPrevious());
}
}
var controller = new Controller();
var router = new Router({
controller: Mod.controller
});
controller.start();
Using this approach allows you to decouple your views and collection. This will make your code reusable (using the controls view in a different context as an example).

Answer 2

You are looking for CollectionView or CompositeView.
The CollectionView will loop through all of the models in the
specified collection, render each of them using a specified itemView,
then append the results of the item view's el to the collection view's
el.
A CompositeView extends from CollectionView to be used as a
composite view for scenarios where it should represent both a
branch and leaf in a tree structure, or for scenarios where a
collection needs to be rendered within a wrapper template.