I just realized that Backbone.Model#toJSON gets called on every Backbone.Model#fetch. It even gets called when when a corresponding Collection is fetched. Is this intensional? I'd expect toJSON to be called only on Backbone.Model#save. I'm using Backbone 0.0.3.

This causes problems in my case since my models (documents) aren't in a valid (serializable state) before they've been fetched and parsed.

In my scenario I'd like to load a document by just creating a new Document with an id property, then calling fetch.

loadDocument: function(id) {
  this.model = new Document({id: id});
  this.model.fetch({
    success: function() {
      // init doc
    }
  });
},

toJSON is unnecessarily (imo) called here, causing an error, because the document's ContentGraph (this.g) hasn't been setup properly.

toJSON: function() {  
  return _.extend(_.clone(this.attributes), {
    contents: this.g.serialize()
  });
},

My parse function looks like this:

parse: function(res) {
  if (res.contents) {
    this.g = new ContentGraph(res.contents);
  }
  return res;
},