Question

Is it possible to make Backbone.js work with compound keys?

Id est, instead of setting id or idAttributemodel to a specific value, I want to know Backbone.js that I will be using more than one property. In such a way, every RESTful call would be made sending those two parameters to identify the object we’re talking about.

For the sake of an example, let’s say that I want to update a person’s debt to a specific person, and the model is:

Borrower (borrowerId, name, ...)
Lender (lenderId, name, ...)
Debt (borrowerId, lenderId, debtAmount)

So, I now want to make Backbone.js update/delete a debt object. How can I make it work with the compound key (borrowerId, lenderId)?

Answer 1

You could override the url() implementation of your model, as suggested in Backbone’s documentation:

var Debt = Backbone.Model.extend({
  url: function() {
    var base = /* your base URL here */;
    if (this.isNew()) return base;
    return base + (base.charAt(base.length - 1) == '/' ? '' : '/') + encodeURIComponent(this.get("borrowerId")+"_"+this.get("lenderId"));
  }
});

The above code would result in URLs of the form baseURL/borrowerId_lenderId. Note that you may want to take a collections base URL into account when constructing the model’s URL.