Backbone JS: can one view trigger updates in other

Question

In my simple project I have 2 views - a line item view (Brand) and App. I have attached function that allows selecting multiple items:

var BrandView = Backbone.View.extend({
...some code...
    toggle_select: function() {
        this.model.selected = !this.model.selected;
        if(this.model.selected) $(this.el).addClass('selected');
        else $(this.el).removeClass('selected');
        return this;
    }
});

var AppView = Backbone.View.extend({
...some code...
    delete_selected: function() {
        _.each(Brands.selected(), function(model){ 
            model.delete_selected();
        });
        return false;
    },
});

Thing is, I want to know how many items are selected. In this setup selecting is NOT affecting the model and thus not firing any events. And from MVC concept I understand that views should not be directly talking to other views. So how can AppView know that something is being selected in BrandViews?

And more specifically, I AppView to know how many items were selected, so if more than 1 is selected, I show a menu for multiple selection.

Answer 1

Here is my case with a similar need: Backbone listenTo seemed like a solution to redirect to login page for timed out or not authenticated requests.

I added event handler to my router and made it listen to the global event such as:

Backbone.Router.extend({
    onNotAuthenticated:function(errMsg){
        var redirectView = new LoginView();
        redirectView.displayMessage(errMsg);
        this.loadView(redirectView);
    },
    initialize:function(){
        this.listenTo(Backbone,'auth:not-authenticated',this.onNotAuthenticated);  
    },
    .....
});

and in my jquery ajax error handler:

$(document).ajaxError(
    function(event, jqxhr, settings, thrownError){
        .......
        if(httpErrorHeaderValue==="some-value"){
             Backbone.trigger("auth:not-authenticated",errMsg);
        }
    });