updating Backbone submodels after fetch/save

In my Backbone application I have a model consisting of a couple of sub-models as parameters.

I define it so:

app.Models.Account = Backbone.Model.extend({

    initialize : function( ) {
        this.set( { 
                info     : new app.Models.Info(),
                logins   : new app.Collections.Logins(),
                billing  : new app.Models.Billing(),
            } );
    }

});

The problem is when fetching and saving. When I fetch for example the JSON response includes an object for info , an array for logins and an object for billing . Backbone automatically assigns them as normal parameters which means the sub-models are overridden with a simple object.

My current solution is to override the fetch method for the model like so:

    fetch: function( options ) {
      options = options ? _.clone(options) : {};
      var model = this;
      var success = options.success;
      options.success = function(resp, status, xhr) {
        resp = model.parse( resp, xhr );

        model.get('info').set(resp.info);

        model.get('logins').reset(resp.logins);

        model.get('billing').set(resp.billing);

        if (success) success(model, resp);
      };

      options.error = Backbone.wrapError(options.error, model, options);
      return (this.sync || Backbone.sync).call(this, 'read', this, options);
    }

however this is only for fetch. And since the updated status of the model created is returned when calling the save() method I have to also override the save() method.

Are there any good approaches to solve this issue?

Perhaps overriding the set() method could work, however I fear that would mean that I would be beginning to go astray from the Backbone codebase.

I also thought about using the parse method like so

    parse : function ( response ) {
        this.model.get('info').set(response.info);
        response.info = this.model.get('info');

        this.model.get('logins').reset(response.logins);
        response.logins = this.model.get('logins')

        this.model.get('billing').set(response.billing);
        response.billing = this.model.get('billing');

        return response;
    }

which would create a reference to the already updated sub model.

---

I generally use parse for sub-models, as in your second example (though note that you need to return response at the end). I think this is conceptually accurate, as parse is the appropriate place for transforming the server-side representation into a client-side one. I believe this should work for save as well, though I haven't tested it, since parse is called on the save response too.

In my experience, overriding set is nothing but trouble - it tends to have unintended side-effects, and is better avoided.

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