Question

I have a code:

Application = function() {
    Application.prototype.currentQuote.collection.fetch();
};

Application.prototype = {}

Application.prototype.currentQuote = {};
Application.prototype.currentQuote.model = new (Backbone.Model.extend({
    defaults: {
        products: []
    }
}))();

Application.prototype.currentQuote.collection = new (Backbone.Collection.extend({
    model: Application.prototype.currentQuote.model,
    url: 'test.json'
}))();

App = new Application();

But, when collection is fetched, i get “Uncaught TypeError: object is not a function” error.
I dont understand why, and what i can fix it?

You can see test case here: https://dl.dropbox.com/u/15806777/development/bb/index.html

Thanks!

Answer 1

I’d guess that your problem is right here:

Application.prototype.currentQuote.collection = new (Backbone.Collection.extend({
    model: Application.prototype.currentQuote.model, // <------------------------
    url: 'test.json'
}))();

A collection’s model is:

the model class that the collection contains.

So the model should be something that comes from Backbone.Model.extend({...}) (i.e. “class”) rather than something that comes from new (Backbone.Model.extend({...})) (i.e. a model instance). When you ask a collection to create some models (through the constructor call, fetch, add, …), the collection needs something that it can use new on and you can’t new model_instance because the new operator needs a constructor function:

The new operator creates an instance of a user-defined object type or of one of the built-in object types that has a constructor function.

That’s where your “Uncaught TypeError: object is not a function” error comes from.

You’ll need something like this:

Application.prototype.currentQuote.Model = Backbone.Model.extend({
    defaults: {
        products: []
    }
});
//...
Application.prototype.currentQuote.collection = new (Backbone.Collection.extend({
    model: Application.prototype.currentQuote.Model,
    url: 'test.json'
}))();