why behaviors are not allowed to pass dynamically? - backbone.js

Question

I am working on Marionette.behavior.I was trying to pass the behaviors hash dynamically at the time of view initialization but it is not getting assigned to the behaviors object of view.because behaviors are getting initialized at the time of view construction.
so we achieved the solution in the following way but is it the right way to achieve it?
is there any other way to achieve? and
why behaviors are not allowed to pass dynamically?
Here's the code:
var Behaviour = new Marionette.Application();
Behaviour.addRegions({
mainRegion:"#main-region"
});
var Person = Backbone.Model.extend({
defaults:{
firstName:"NA",
lastName:"NA",
phoneNumber:"NA",
presentAddr:"NA",
permanantAddr:"NA"
}
});
var buttonView=Marionette.ItemView.extend({
template:"#buttontemplate",
constructor:function(options){
this.behaviors = options.behaviors;
Marionette.ItemView.apply(this, arguments);
},
events:{
"click .display":"displayDetail"
},
displayDetail:function(){
this.triggerMethod("DisplayPersonDetails");
},
//behaviors:{Behavior1:{ },Behavior2:{ }}
})
var PersonDetailsView = Marionette.ItemView.extend({
template:"#static-template",
ui: {
"Change": ".change"
},
events:{
"click #ui.Change":"changeBehavior"
},
changeBehavior:function(){
},
});
var Behavior1 = Marionette.Behavior.extend({
onDisplayPersonDetails:function(){
var person=new Person({firstName:"abhijeet",lastName:"avhad",phoneNumber:"9604074690",permanantAddr:"sangamner",presentAddr:""})
var myView = new PersonDetailsView({model:person});
Behaviour.mainRegion.show(myView);
}
});
var Behavior2 = Marionette.Behavior.extend({
onDisplayPersonDetails:function(){
var person =new Person({firstName:"abhijeet",lastName:"avhad",phoneNumber:"9604074690",permanantAddr:"",presentAddr:"shivajinagar"})
var myView =new PersonDetailsView({model:person});
Behaviour.mainRegion.show(myView);
}
});
Behaviour.on("initialize:after", function(){
console.log(" started!");
Marionette.Behaviors.behaviorsLookup = function() {
return window.Behaviors;
};
window.Behaviors = {};
window.Behaviors.Behavior1 = Behavior1;
window.Behaviors.Behavior2 = Behavior2;
var buttonview=new buttonView({behaviors:{Behavior1:{ },Behavior2:{}}});
Behaviour.mainRegion.show(buttonview);
});
Behaviour.start();

Answer 1

The other way of achieving that is in your definition declare a function that returns the behaviors supplied at initialization, like this:
var buttonView=Marionette.ItemView.extend({
...
behaviors: function () {
return this.options.behaviors;
},
...

Answer 2

This is because the Marionette applies the behaviors in the constructor:
if (_.isObject(this.behaviors)) {
new Marionette.Behaviors(this);
}
You may try to do the same in your initialize method, but I'm not sure if it will work correctly if you already had some behaviors assigned beforehand.

Answer 3

After hacking through the source, I've come up with the following. It breaks encapsulation, which leads me to believe that there is probably a better way. Nonetheless, until I find it, this is going straight into production.
// Define Behavior.
var Behavior1 = { /* Behavior definition */ }
// Create View like normal.
var view = new ItemView({
behaviors: {
behavior1: { behaviorClass: Behavior1 }
}
});
// Here's the ugly part.
view.undelegateEvents();
view._behaviors = Marionette.Behaviors(subview);
view.delegateEvents();
After you do that, your Behaviors should all work.

Answer 4

Behavior can be passed directly with behaviorClass property within declaration of behaviors:
As seen in the marionette.behaviors docs, for example we have Tooltip behavior, which we want to pass directly and not from global list.
define(['marionette', 'lib/tooltip'], function(Marionette, Tooltip) {
var View = Marionette.ItemView.extend({
behaviors: {
Tooltip: {
behaviorClass: Tooltip, // <-- passing the behavior directly here
message: "hello world"
}
}
});
});