update for Backbone.Collection

update.js

  update: function(options){
    options = options || {};

    var collection = this, success = options.success;

    options.success = function(resp, status, xhr){
      var changed = false;
      var collectionIds = []; // store the ids as we add them
      var toDelete = []; // store all the models to remove
      var onChange = function() {
        this.unbind("change", onChange);
        changed = true;
      };

      // add/ update
      _(collection.parse(resp, xhr)).each(function(item){
        var model = collection.get(item.id);
        var triggerChange = {};
        var key, update = {};

        if (!model){
          collection.add(item, options);
          changed = true;

          collectionIds.push(item.id); // update ids
        } else {
          model.bind("change", onChange);
          model.set(item);
          model.unbind("change", onChange); // remove binding that may have not been triggered

          collectionIds.push(model.id); // update ids
        }

      });

      // generate a list of models to remove from the collection
      if (collection.length !== collectionIds.length) {
        toDelete = collection.filter(function(model){
          return collectionIds.indexOf(model.id) === -1;
        });
      }

      // remove all the models that were not sent back
      if (toDelete.length) {
        changed = true;
        collection.remove(toDelete, options);
      }

      // trigger collection events
      if (!options.silent && changed) {
        collection.trigger('changed', collection, options);
      }

      if (success) {
        success(collection, resp);
      }
    };

    return (this.sync || Backbone.sync).call(this, 'read', this, options);
  },