BackboneJS Associations - Document HasMany Categories

document.js

var Document = Backbone.Model.extend({

  initialize: function() {
    var categories = new App.Collections.Categories();
    var self = this;
    categories.url = function() {
        return self.url() + '/categories';
    };

    self.set({
      categories: categories 
    });
  },

  validate: function(attrs) {
    var errors = { document: {}};
    if (attrs.name === "") {
      errors.document["name"] = "Name cannot be blank";
    }
    if (!jQuery.isEmptyObject(errors.document)) {
      return errors;
    } 
    
  }, 

  url: function() {
    var base = 'documents';
    if (this.isNew()) {
      return base;
    }
    return base + (base.charAt(base.length - 1) == '/' ? '' : '/') + this.id;
  },

  addCategory: function(category, options) {
    var self = this;
    options || (options = {});
    _.extend(options, {document_id: self.get('id')});
  
    category.save(options,
    {
      success: function(model,resp) {
        self.get('categories').add(category,{silent: true}); 
      },
      error: function(model, resp) {
        debugger;
        new App.Views.Notice({ message: resp});
      }
    });
  },

  deleteCategory: function(cat) {
    this.categories.remove(cat, {silent: true})
  },

  //delete categories one by one
  deleteAllCategories: function() {
    var self = this;
    _.each(self.categories, function(el) {
      el.destroy({success: function(model, resp) {
        self.deleteCategory(el);
        }
      })
    })
  },

  //this would call addCategory for each
  addCategories: function(arrayOfCats) {
  },

  //this would figure out a way to do the update in a single json request (e.g. by using $.ajax)
  addBulkCategories: function(arrayofCats) {
  },

  //delete all through bulk json update
  deleteAllBulkCategories: function() {
  }

  ,toJSON: function() {

    json = this.attributes;
    return _.extend(json, {categories_attributes: this.get('categories').toJSON()});//TODO: inherit this centrally

  }


});