Using this.ajax inside a model

comment.js

App.Models.Comment = Backbone.Model.extend(_.extend({}, App.Mixins.Ajax, {
  urls: {
    flag: '/comments/flag_comment/:id'
  },

  flag: function(formData) {
    this.set('is_flagged', true);
    return this.ajax('flag', {
      data: formData,
      error: function() {
        this.set('is_flagged', false);
      }
    });
  }
}));