Backbone.js - How to use a custom model property in a template?

Question

This might be a really simple question but I'm having a heck of a time finding an answer.

Using backbone, I have this line:

Person = Backbone.Model.extend();

I then use that in a collection filled from a URL. For the sake of the example, say I have a first and last name, and I want to do something like:

Person = Backbone.Model.extend({
    FullName: this.get("firstName") + " " + this.get("lastName")
});

I can call that inside backbone using, for example, People.first().FullName(). But if I pass People.first() to my view and render that in a template, it seems to have no knowledge what FullName is.

How would I add a custom property to a model in Backbone and use that inside a template?

Cheers!

Answer 1

Your FullName definition doesn't make any sense so I'm going to assume that you really meant this:

Person = Backbone.Model.extend({
    FullName: function() {
        return this.get("firstName") + " " + this.get("lastName");
    }
});

Usually you'll call toJSON on your models to serialize them for use by a template:

var html = template({ person: person.toJSON() })

The default toJSON simply returns a (shallow) copy of the model's internal attributes. The attributes will, presumably, have both firstName and lastName properties but FullName is a function on the model so it won't be in the attributes.

You could provide your own toJSON:

toJSON: function() {
    var j = _(this.attributes).clone();
    j.FullName = this.FullName();
    return j;
}

and then you'd have a FullName in your template. However, toJSON is also used to serialize the model to send data to the server; your server would end up seeing a FullName and it might get upset about that. You could add another serializer specifically for templates:

// `serialize` is another common name for this
for_template: function() {
    var j = this.toJSON();
    j.FullName = this.FullName();
    return j;
}

and then use that function to supply data for your templates:

var html = template({ person: person.for_template() });

Answer 2

I struggled with this for a while too, but I found a solution.

Its covered in a fair amount of depth, including a solution to the issue of toJSON being used to send the server data, in Backbone Computed Properties