Using the Simpl Decorator

The simpl decorator allows your app to stay in sync with relevant changes by subscribing to notifications from the modelservice. The UI will receive an action and its store will be updated every time a Scope within a subscribed topic is added, updated or deleted.

In addition to defining your combined Redux reducers and store, you will need a Presentational component that displays progress in loading Simpl data into the Redux store. This component depends on the simpl-react CONNECTION_STATUS property to track progress. The simpl-ui-cookiecutter cookiecutter template provides such a progress component in js/components/Progress.js.

To connect your application to its Redux store and reducers, you must wrap your root Container component in the simpl decorator. The simpl-ui-cookiecutter cookiecutter template does this for you by providing js/modules/Root.js:

import React from 'react';
import PropTypes from 'prop-types';

import {connect} from 'react-redux';
import {Router, Route, browserHistory} from 'react-router';

import {SimplActions} from 'simpl-react/lib/actions';
import {simpl} from 'simpl-react/lib/decorators/simpl';

import Progress from '../components/Progress';


const RootContainer = connect(

const runs = => `${id}`);
const runusers = => `model:model.runuser.${id}`);
const worlds = => `${id}`);
const topics = (LEADER) ? runs : runusers.concat(worlds);
console.log("topics: ", topics);

export default simpl({
  authid: AUTHID,
  password: 'nopassword',
  url: `${MODEL_SERVICE}`,
  progressComponent: Progress,
  root_topic: ROOT_TOPIC,
  topics: () => topics,
  loadAllScenarios: false

The topics argument passed to the simpl decorator is initialized from Javascript constants defined in the frontend Django app’s templates/frontend/home.html using data returned by the frontend app’s HomeView.get_context_data method in’`.

The loadAllScenarios argument passed to the simpl decorator indicates whether the current user should have access to other users’ scenarios. The default setting of false makes sense for multi-player games. Players in multi-player games typically have access to their own scenarios and their world’s shared scenarios. In multi-player games, leaders typically have access to their own scenarios and to all world scenarios.