redux-rx

RxJS utilities for Redux. Includes

• A utility to create Connector-like smart components using RxJS sequences.
  • A special version of bindActionCreators() that works with sequences.
• An FSA-compliant observable middleware
• A utility to create a sequence of states from a Redux store.

npm install --save redux-rx rx

Usage

import { createConnector } from 'redux-rx/react';
import { bindActionCreators, observableMiddleware, observableFromStore } from 'redux-rx';

createConnector(selectState, ?render)

This lets you create Connector-like smart components using RxJS sequences. selectState() accepts three sequences as parameters

• props$ - A sequence of props passed from the owner
• state$ - A sequence of state from the Redux store
• dispatch$ - A sequence representing the dispatch() method. In real-world usage, this should sequence only has a single value, but it's provided as a sequence for correctness.

selectState() should return a sequence of props that can be passed to the child. This provides a great integration point for sideways data-loading.

Here's a simple example using web sockets:

const TodoConnector = createConnector((props$, state$, dispatch$) => {
  // Special version of bindActionCreators that works with sequences; see below
  const actionCreators$ = bindActionCreators(actionCreators, dispatch$);
  const selectedState$ = state$.map(s => s.messages);

  // Connect to a websocket using rx-dom
  const $ws = fromWebSocket('ws://chat.foobar.org').map(e => e.data)
    .withLatestFrom(actionCreators$, (message, ac) =>
      () => ac.receiveMessage(message)
    )
    .do(dispatchAction => dispatchAction()); // Dispatch action for new messages

  return combineLatest(
    props$, selectedState$, actionCreators$, $ws,
    (props, selectedState, actionCreators) => ({
      ...props,
      ...selectedState,
      ...actionCreators
    }));
});

Pretty simple, right? Notice how there are no event handlers to clean up, no componentWillReceiveProps(), no setState. Everything is just a sequence.

If you're new to RxJS, this may look confusing at first, but — like React — if you give it a try you may be surprised by how simple and fun reactive programming can be.

TODO: React Router example. See this comment for now.

render() is an optional second parameter which maps child props to a React element (vdom). This parameter can also be a React Component class — or, if you omit it entirely, a higher-order component is returned. See createRxComponent() of react-rx-component for more details. (This function is a wrapper around that library's createRxComponent().)

Not that unlike Redux's built-in Connector, the resulting component does not have a select prop. It is superseded by the selectState function described above. Internally, shouldComponentUpdate() is still used for performance.

NOTE createConnector() is a wrapper around react-rx-component. Check out that project for more information on how to use RxJS to construct smart components.

bindActionCreators(actionCreators, dispatch$)

This is the same, except dispatch$ can be either a dispatch function or a sequence of dispatch functions. See previous section for context.

observableMiddleware

The middleware works on RxJS observables, and Flux Standard Actions whose payloads are observables.

The default export is a middleware function. If it receives a promise, it will dispatch the resolved value of the promise. It will not dispatch anything if the promise rejects.

If it receives an Flux Standard Action whose payload is an observable, it will

• dispatch a new FSA for each value in the sequence.
• dispatch an FSA on error.

The middleware does not subscribe to the passed observable. Rather, it returns the observable to the caller, which is responsible for creating a subscription. Dispatches occur as a side effect (implemented using doOnNext() and doOnError()).

Example

// fromEvent() used just for illustration. More likely, if you're using React,
// you should use something rx-react's FuncSubject
// https://github.com/fdecampredon/rx-react#funcsubject
const buttonClickStream = Observable.fromEvent(button, 'click');

// Stream of new todos, with debouncing
const newTodoStream = buttonClickStream
  .debounce(100)
  .map(getTodoTextFromInput);

// Dispatch new todos whenever they're created
dispatch(newTodoStream).subscribe();

observableFromStore(store)

Creates an observable sequence of states from a Redux store.

This is a great way to react to state changes outside of the React render cycle. See this discussion for an example. I'll update with a proper example once React Router 1.0 is released.

Also, I'm not a Cycle.js user, but I imagine this is useful for integrating Redux with that library.