gaearon / redial

Universal data fetching and route lifecycle management for React etc.

redial

Universal data fetching and route lifecycle management for React etc.

$ npm install --save redial

Why?

When using something like React Router, you'll want to ensure that all data for a set of routes is prefetched on the server before attempting to render.

However, as your application grows, you're likely to discover the need for more advanced route lifecycle management.

For example, you might want to separate mandatory data dependencies from those that are allowed to fail. You might want to defer certain data fetching operations to the client, particularly in the interest of server-side performance. You might also want to dispatch page load events once all data fetching has completed on the client.

In order to accommodate these scenarios, the ability to define and trigger your own custom route-level lifecycle hooks becomes incredibly important.

Providing lifecycle hooks

The @provideHooks decorator allows you to define hooks for your custom lifecycle events, returning promises if any asynchronous operations need to be performed. When using something like React Router, you'll want to decorate your route handlers rather than lower level components.

For example:

import { provideHooks } from 'redial';

import React, { Component } from 'react';
import { getSomething, getSomethingElse, trackDone } from 'actions/things';

@provideHooks({
  fetch: ({ dispatch, params: { id } }) => dispatch(getSomething(id)),
  defer: ({ dispatch, params: { id } }) => dispatch(getSomethingElse(id)),
  done: ({ dispatch }) => dispatch(trackDone())
})
class MyRouteHandler extends Component {
  render() {
    return <div>...</div>;
  }
}

If you'd prefer to avoid using decorators, you can use provideHooks as a plain old function:

const hooks = {
  fetch: ({ dispatch, params: { id } }) => dispatch(getSomething(id)),
  defer: ({ dispatch, params: { id } }) => dispatch(getSomethingElse(id)),
  done: ({ dispatch }) => dispatch(trackDone())
};

class MyRouteHandler extends Component {
  render() {
    return <div>...</div>;
  }
}

export default provideHooks(hooks)(MyRouteHandler);

Triggering lifecycle events

Once you've decorated your components, you can then use the trigger function to initiate an event for an arbitrary array of components, or even a single component if required. Since hooks tend to be asynchronous, this operation always returns a promise.

For example, when fetching data before rendering on the server:

import { trigger } from 'redial';

const locals = {
  some: 'data',
  more: 'stuff'
};

trigger('fetch', components, locals).then(render);

Dynamic locals

If you need to calculate different locals for each lifecycle hook, you can provide a function instead of an object. This function is then executed once per decorator, with a static reference to the component provided as an argument.

For example, this would allow you to calculate whether a component is being rendered for the first time and pass the result in via the locals object:

const getLocals = component => ({
  isFirstRender: prevComponents.indexOf(component) === -1
});

trigger('fetch', components, getLocals).then(render);

Example Usage with React Router and Redux

When server rendering with React Router (or using the same technique to render on the client), the renderProps object provided to the match callback has an array of routes, each of which has a component attached. You're also likely to want to pass some information from the router to your decorator functions.

In order to dispatch actions from within your decorators, you'll want to pass in a reference to your store's dispatch function. This works especially well with redux-thunk to ensure your async actions return promises.

For example:

import { trigger } from 'redial';
import React from 'react';
import { renderToString } from 'react-dom/server';
import createMemoryHistory from 'history/lib/createMemoryHistory';
import useQueries from 'history/lib/useQueries';
import { RoutingContext, match } from 'react-router';
import { createStore, applyMiddleware } from 'redux';
import { Provider } from 'react-redux';
import thunk from 'redux-thunk';

// Your app's reducer and routes:
import reducer from './reducer';
import routes from './routes';

// Render the app server-side for a given path:
export default path => new Promise((resolve, reject) => {
  // Set up Redux:
  const createStoreWithMiddleware = applyMiddleware(thunk)(createStore);
  const store = createStoreWithMiddleware(reducer);
  const { dispatch } = store;

  // Set up history for router:
  const history = useQueries(createMemoryHistory)();
  const location = history.createLocation(path);

  // Match routes based on location object:
  match({ routes, location }, (routerError, redirectLocation, renderProps) => {
    // Get array of route components:
    const components = renderProps.routes.map(route => route.component);

    // Define locals to be provided to all fetcher functions:
    const locals = {
      path: renderProps.location.pathname,
      query: renderProps.location.query,
      params: renderProps.params,

      // Allow fetcher functions to dispatch Redux actions:
      dispatch
    };

    // Wait for async actions to complete, then render:
    trigger('fetch', components, locals)
      .then(() => {
        const data = store.getState();
        const html = renderToString(
          <Provider store={store}>
            <RoutingContext {...renderProps} />
          </Provider>
        );

        resolve({ data, html });
      })
      .catch(reject);
  });
});

Related projects

• React Resolver by @ericclemmons
• React Transmit by @rygu
• AsyncProps for React Router by @ryanflorence
• React Async by @andreypopp

License

MIT License