Question

If a backbone model (or collection) may or may not already exists, how do you extend or mixin?

Here’s what I’ve tried:

mymodels.A = ('A' in mymodels ? mymodels.A : Backbone.Model).extend({
 /* url, initialize, parse, etc... */ 
});

or

mymodels.A = ('A' in mymodels ? mymodels.A.prototype : Backbone.Model).extend({
 /* url, initialize, parse, etc... */
});

or

mymodels.A = _.extend('A' in mymodels ? mymodels.A : Backbone.Model, {
 /* url, initialize, parse, etc... */
});

Thoughts?

Edit:

mymodels.A = (mymodels.A || Backbone.Model).extend({
 /* url, initialize, parse, etc... */
});

Edit2:

Took a different approach….see answer below

Answer 1

This accomplished what I was trying to do….which was create model in pieces. In the end, I create an object in pieces and pass the whole object to Backbone.Model.extend:

var mymodels = {};

mymodels.A = _.extend({}, mymodels.A, {
    url: "http://www.google.com"
});

mymodels.A = _.extend({}, mymodels.A, {
    initialize: function(){
        this.set('mixin', 'TRUE'); 
    }
});
mymodels.A = Backbone.Model.extend(mymodels.A);

var model = new mymodels.A({'new': 'TRUE'});