Makes Backbone.js play nicely with default Rails setup

backbone.rails.js

//
//     Backbone.Rails.js
//
//     Makes Backbone.js play nicely with the default Rails setup, i.e.,
//     no need to set
//       ActiveRecord::Base.include_root_in_json = false
//     and build all of your models directly from `params` rather than
//     `params[:model]`.
//
//     Load this file after backbone.js and before your application JS.
//

Backbone.RailsJSON = {
  // In order to properly wrap/unwrap Rails JSON data, we need to specify
  // what key the object will be wrapped with.
  _name : function() {
    if (!this.name) throw new Error("A 'name' property must be specified");
    return this.name;
  },

  // A test to indicate whether the given object is wrapped.
  isWrapped : function(object) {
    return (object.hasOwnProperty(this._name()) &&
        (typeof(object[this._name()]) == "object"));
  },

  // Extracts the object's wrapped attributes.
  unwrappedAttributes : function(object) {
    return object[this._name()];
  },

  // Wraps the model's attributes under the supplied key.
  wrappedAttributes : function() {
    var object = new Object;
    object[this._name()] = _.clone(this.attributes);
    return object;
  },

  // Sets up the new model's internal state so that it matches the
  // expected format. Should be called early in the model's constructor.
  maybeUnwrap : function(args) {
    if (this.isWrapped(args)) {
      this.set(this.unwrappedAttributes(args), { silent: true });
      this.unset(this._name(), { silent: true });
      this._previousAttributes = _.clone(this.attributes);
    }
  }
};

_.extend(Backbone.Model.prototype, Backbone.RailsJSON, {
  // This is called on all models coming in from a remote server.
  // Unwraps the given response from the default Rails format.
  parse : function(resp) {
    return this.unwrappedAttributes(resp);
  },

  // This is called just before a model is persisted to a remote server.
  // Wraps the model's attributes into a Rails-friendly format.
  toJSON : function() {
    return this.wrappedAttributes();
  },

  // A new default initializer which handles data directly from Rails as
  // well as unnested data.
  initialize : function(args) {
    this.maybeUnwrap(args);
  }
}); 

Hey bernat,

No, there's not a bit of documentation for this -- it's just a snippet I hacked together one weekend. It sounds like you just need to add a name attribute (which should be the key the JSON will be nested under) to your model:
var Widget = Backbone.Model.extend({
name: 'widget'
});

One thing to watch out for: since Backbone.js doesn't provide a create callback, I've had to add a default initializer which actually unwraps the JSON. If you override initialize in your model, you'll need to call this.maybeUnwrap(args) early in the new method.

Jeff

Thanks, just what I needed!

Thanks!

thanks worked great

this should be moved to a repo so it can be searched/contributed to.

I just tried upgrading to Backbone 0.9.2 and now I'm getting this error: Uncaught TypeError: Cannot call method 'hasOwnProperty' of undefined. Anyone have a fix to suggest?

@drewda, your comment was 11 months ago, but I ran into this, too. My fix was to give it an || {} when it was asking for args in case args was undefined. Hope that helps anyone who gets here from Google.

Check this one: https://gist.github.com/jumski/1128000