How to clear view model in Durandal

Question

Is there a way to selectively tell Durandal to reinitialize a view model. I am aware of the singleton vs new instance approaches to initialize view models.

//singleton since a declared object is returned
define(function() {
    return { prop1: 1, prop2: 2 }
});

//new instance since a constructor is returned
define(function() {

var ctor = function(){};

    return ctor;
});

I generally don't like to declare view models as singletons, but I have to do it in a special case due to sub routing which requires me to pass data from a parent router to my child router. However, the singleton has other side effects, so I was wondering: Is there a way to selectively request a new instance of the view model even if it was initially declared as a singleton?

gerrod gerrod · Accepted Answer · 2014-03-17T05:50:23

Not that I know of - this is more of a limitation of requirejs versus Durandal, though. Once require has loaded the module, so far as I know it will always return you the same version of that module. Unless there's a way to tell require to reload the module?

The only thing I could think of would be to "reset" the view model during the activate method. If you're changing routes and finding that the activate method isn't being called, it may be because Durandal thinks that your module is already active (in which case it won't reactivate). You can change this behavior by customising the areSameItem function for the router (see this question for an explanation).

Hope that helps.

How to clear view model in Durandal

2 Answers