preact-router-redux

Keep your router in sync with application state ✨

You're a smart person. You use Redux to manage your application state. You use Preact Router or React Router to do routing. All is good.

But the two libraries don't coordinate. You want to do time travel with your application state, but Preact Router doesn't navigate between pages when you replay actions. It controls an important part of application state: the URL.

This library helps you keep that bit of state in sync with your Redux store. We keep a copy of the current location hidden in state. When you rewind your application state with a tool like Redux DevTools, that state change is propagated to Preact Router so it can adjust the component tree accordingly. You can jump around in state, rewinding, replaying, and resetting as much as you'd like, and this library will ensure the two stay in sync at all times.

This library is not necessary for using Redux together with Preact Router. You can use the two together just fine without any additional libraries. It is useful if you care about recording, persisting, and replaying user actions, using time travel. If you don't care about these features, just use Redux and Preact Router directly.

Installation

yarn add preact-router-redux # or
npm install --save preact-router-redux

How It Works

This library allows you to use Preact Router's APIs as they are documented. And, you can use redux like you normally would, with a single app state. The library simply enhances a history instance to allow it to synchronize any changes it receives into application state.

history + store (redux) → preact-router-redux → enhanced history → preact-router

Tutorial - MAY BE BROKEN - transition

Let's take a look at a simple example.

import { h, render } from 'preact'
import { createStore, combineReducers } from 'redux'
import { Provider } from 'preact-redux'
import { Router, Route } from 'preact-router'
import { browserHistory } from './history'  // create this with history/createBrowserHistory
import { syncHistoryWithStore, routerReducer } from 'preact-router-redux'
 
import reducers from '<project-path>/reducers'
import browserHistory from '<project-path>//history'  // create this with history/createBrowserHistory
 
// Add the reducer to your store on the `routing` key
const store = createStore(
  combineReducers({
    ...reducers,
    routing: routerReducer
  })
)
 
// Create an enhanced history that syncs navigation events with the store
const history = syncHistoryWithStore(browserHistory, store)
 
render(
  <Provider store={store}>
    { /* Tell the Router to use our enhanced history */ }
    <Router history={history}>
      <Route path="/" component={Main}>
      <Route path="/foo" component={Foo}/>
      <Route path="/bar" component={Bar}/>
    </Router>
  </Provider>,
  document.getElementById('mount')
)

Now any time you navigate, which can come from pressing browser buttons or navigating in your application code, the enhanced history will first pass the new location through the Redux store and then on to Preact Router to update the component tree. If you time travel, it will also pass the new state to React Router to update the component tree again.

How do I watch for navigation events, such as for analytics?

Simply listen to the enhanced history via history.listen. This takes in a function that will receive a location any time the store updates. This includes any time travel activity performed on the store.

const history = syncHistoryWithStore(browserHistory, store)
 
history.listen(location => analyticsService.track(location.pathname))

For other kinds of events in your system, you can use middleware on your Redux store like normal to watch any action that is dispatched to the store.

What if I use Immutable.js or another state wrapper with my Redux store?

When using a wrapper for your store's state, such as Immutable.js, you will need to change two things from the standard setup:

1. By default, the library expects to find the history state at state.routing. If your wrapper prevents accessing properties directly, or you want to put the routing state elsewhere, pass a selector function to access the historystate via the selectLocationState option on syncHistoryWithStore.
2. Provide your own reducer function that will receive actions of type LOCATION_CHANGE and return the payload merged into the locationBeforeTransitions property of the routing state. For example, state.set("routing", {locationBeforeTransitions: action.payload}).

These two hooks will allow you to store the state that this library uses in whatever format or wrapper you would like.

How do I access router state in a container component?

Preact Router provides route information via a route component's props as does React Router. This makes it easy to access them from a container component. When using preact-redux to connect() your components to state, you can access the router's props from the 2nd argument of mapStateToProps, and similarly on react-redux:

function mapStateToProps(state, ownProps) {
  return {
    id: ownProps.params.id,
    filter: ownProps.location.query.filter
  };
}

You should not read the location state directly from the Redux store. This is because Preact Router operates asynchronously (to handle things such as dynamically-loaded components) and your component tree may not yet be updated in sync with your Redux state. You should rely on the props passed by Preact Router, as they are only updated after it has processed all asynchronous code.

What if I want to issue navigation events via Redux actions?

History provides mehtods createBrowserHistory and createHashHistory which can be used to create singleton versions of history (e.g. browserHistory and hashHistory) that you can import and use from anywhere in your application. However, if you prefer Redux style actions, the library also provides a set of action creators and a middleware to capture them and redirect them to your history instance.

import { createStore, combineReducers, applyMiddleware } from 'redux';
import { routerMiddleware, push } from 'preact-router-redux'
 
// Apply the middleware to the store
const middleware = routerMiddleware(browserHistory)
const store = createStore(
  reducers,
  applyMiddleware(middleware)
)
 
// Dispatch from anywhere like normal.
store.dispatch(push('/foo'))

Examples

None yet!

→ Have an example to add? Send us a PR! ←

API

routerReducer()

You must add this reducer to your store for syncing to work.

A reducer function that stores location updates from history. If you use combineReducers, it should be nested under the routing key.

history = syncHistoryWithStore(history, store, [options])

Creates an enhanced history from the provided history. This history changes history.listen to pass all location updates through the provided store first. This ensures if the store is updated either from a navigation event or from a time travel action, such as a replay, the listeners of the enhanced history will stay in sync.

You must provide the enhanced history to your <Router> component. This ensures your routes stay in sync with your location and your store at the same time.

The options object takes in the following optional keys:

• selectLocationState - (default state => state.routing) A selector function to obtain the history state from your store. Useful when not using the provided routerReducer to store history state. Allows you to use wrappers, such as Immutable.js.
• adjustUrlOnReplay - (default true) When false, the URL will not be kept in sync during time travel. This is useful when using persistState from Redux DevTools and not wanting to maintain the URL state when restoring state.

push(location), replace(location), go(number), goBack(), goForward()

You must install routerMiddleware for these action creators to work.

Action creators that correspond with the history methods of the same name. For reference they are defined as follows:

• push - Pushes a new location to history, becoming the current location.
• replace - Replaces the current location in history.
• go - Moves backwards or forwards a relative number of locations in history.
• goForward - Moves forward one location. Equivalent to go(1)
• goBack - Moves backwards one location. Equivalent to go(-1)

Both push and replace take in a location descriptor, which can be an object describing the URL or a plain string URL.

These action creators are also available in one single object as routerActions, which can be used as a convenience when using Redux's bindActionCreators().

routerMiddleware(history)

A middleware you can apply to your Redux store to capture dispatched actions created by the action creators. It will redirect those actions to the provided history instance.

LOCATION_CHANGE

An action type that you can listen for in your reducers to be notified of route updates. Fires after any changes to history.