Backbone Sync with jQuery and a REST API

backbone.sync.js

/*
  Overview:
  - triggers "sync", "sync_success" and "sync_error" messages after sync
  - runs this.url() on the model/collection inputted (note - this function is declared by default in models, not collections. See http://backbonejs.org/#Collection-url for more details)
  - handles the four main REST api methods: POST, PUT, GET, DELETE
  - expects 'create' to return an id, which is auto-set to the newly created model
  - automatically sets parameters when 'fetching' models
  - automatically adds models to collections when 'fetching' collections
  
  EXAMPLES:
    
    E.g. 1: Fetching a model ('GET') from the database, by id.
    var MyModel = Backbone.Model.extend({
      urlRoot: 'apps',
    });
    var model = new MyModel({ id: 123456 });
    model.on('sync', function() {
      // we can now access the model parameters in model/this
    });
    model.fetch();
    
    E.g. 2: Creating a new model in the database with a set of parameters that the user has inputted
    var model = new MyModel();
    model.set({
      name: 'chris',
      age: 23,
      favorite_color: 'red'
    });
    model.on('sync', function() {
      // model has been saved, the 'id' should now be assigned to the model.
    });
    model.save();
    
    E.g. 3: Deleting a model in the database
    var model = new MyModel({ id: 123456 });
    model.on('sync', function() {
      // model has now been deleted in the database
    });
    model.destroy();
    
    
*/
 
 
  // Overrides the backbone sync function
  Backbone.sync = function(method, model, options) {
    var _this = this;
    options = options || {};

    switch (method) {
      case 'create':
        $.ajax({
          method: 'POST',
          url: '/api/'+this.url(),  // url() needs to be manually declared in collections
          data: JSON.stringify(model.attributes),
          dataType: 'json',         // the data type we're expecting back from the server
          contentType: 'application/json',    // the data type we're sending to the server
          success: function(result) {
            model.set('id', result);
            model.hasSynced = true;
            model.trigger('sync');
            model.trigger('sync_success');
          },
          error: function (result) {
            model.hasSynced = true;
            model.trigger('sync');
            model.trigger('sync_error');
          }
        });
      break;

      case 'update':
        $.ajax({
          method: 'PUT',
          url: '/api/'+this.url(),
          data: JSON.stringify(model.attributes),
          dataType: 'json',
          contentType: 'application/json',
          success: function(result) {
            model.hasSynced = true;
            model.trigger('sync');
            model.trigger('sync_success');
          },
          error: function (result) {
            model.hasSynced = true;
            model.trigger('sync');
            model.trigger('sync_error');
          }
        });
      break;

      case 'delete':
        $.ajax({
          method: 'DELETE',
          url: '/api/'+this.url(),
          data: JSON.stringify(model.attributes),
          dataType: 'json',
          contentType: 'application/json',
          success: function(result) {
            model.hasSynced = true;
            model.trigger('sync');
            model.trigger('sync_success');
          },
          error: function (result) {
            model.hasSynced = true;
            model.trigger('sync');
            model.trigger('sync_error');
          }
        });
      break;

      case 'read':
        $.ajax({
          method: 'GET',
          url: '/api/'+this.url(),
          dataType: 'json',
          success: function(result) {
            if (result) {
              if (model instanceof Backbone.Model) {
                model.set(result);
              } else if (model instanceof Backbone.Collection) {
                model.add(result);
              }
            }
            model.hasSynced = true;
            model.trigger('sync');
            model.trigger('sync_success');
          },
          error: function () {
            model.hasSynced = true;
            model.trigger('sync');
            model.trigger('sync_error');
          }
        });
      break;
    }
  };