Skip to content

Latest commit

聽

History

History
193 lines (151 loc) 路 7.69 KB

server-rendering.md

File metadata and controls

193 lines (151 loc) 路 7.69 KB
Raw

Server Side Rendering (using thunk)

Ok, this is the biggest example here, but given what it does, we think it's extremely concise and sensible.

Since the middleware handles the actions it receives asyncronously, on the server you simply await the result of a possible matching thunk:

server/configureStore.js:

import { createStore, applyMiddleware, compose, combineReducers } from 'redux'
import createHistory from 'history/createMemoryHistory'
import { connectRoutes } from 'redux-first-router'

export default async function configureStore(req) {
  const history = createHistory({ initialEntries: [req.path] }) // match initial route to express path

  const routesMap = {
    UNAVAILABLE: '/unavailable',
    ENTITY: { 
      path: '/entity/:slug',
      thunk: async (dispatch, getState) => {
        const { slug } = getState().location.payload
        const data = await fetch(`/api/entity/${slug}`)
        const entity = await data.json()
        const action = { type: 'ENTITY_FOUND', payload: { entity } } // you handle this action type

        dispatch(action)
      }
    },
  }

  const { reducer, middleware, enhancer, thunk } = connectRoutes(history, routesMap) // notice `thunk`
  const rootReducer = combineReducers({ location: reducer })
  // note the order that the enhancer and middleware are composed in: enhancer first, then middleware
  const store = createStore(rootReducer, compose(enhancer, applyMiddleware(middleware)))

  // using redux-thunk perhaps request and dispatch some app-wide state as well, e.g:
  // await Promise.all([ store.dispatch(myThunkA), store.dispatch(myThunkB) ])
  
  await thunk(store) // THE WORK: if there is a thunk for current route, it will be awaited here

  return store
}

server/serverRender.js:

import ReactDOM from 'react-dom/server'
import { Provider } from 'react-redux'
import configureStore from './configureStore'
import App from './components/App'

export default async function serverRender(req, res) {
  const store = await configureStore(req)

  const appString = ReactDOM.renderToString(<Provider store={store}><App /></Provider>)
  const stateJson = JSON.stringify(store.getState())

  // in a real app, you would use webpack-flush-chunks to pass a prop
  // containing scripts and stylesheets to serve in the final string:
  return res.send(
    `<!doctype html>
      <html>
        <body>
          <div id="root">${appString}</div>
          <script>window.REDUX_STATE = ${stateJson}</script>
          <script src="/static/main.js" />
        </body>
      </html>`
  )
}

server/index.js.js:

import express from 'express'
import serverRender from './serverRender'

const app = express()
app.get('*', serverRender)
http.createServer(app).listen(3000)

Note: on the server you won't double dispatch your thunks. Unlike the client, calling the matching thunk is intentionally not automatic so that you can await the promise before sending your HTML to the browser. And of course the thunk returned from connectRoutes will automatically match the current route if called.

Redirects + NOT_FOUND Example

server/configureStore.js:

import { createStore, applyMiddleware, compose, combineReducers } from 'redux'
import createHistory from 'history/createMemoryHistory'
import { connectRoutes, redirect, NOT_FOUND } from 'redux-first-router'

export default async function configureStore(req, res) {
  const history = createHistory({ initialEntries: [req.path] })

  const routesMap = {
    UNAVAILABLE: '/unavailable',
    LOGIN: '/login',
    PRIVATE_AREA: {
      path: '/private-area',
      thunk: (dispatch, getState) => {
        const { isLoggedIn } = getState()           // up to you to handle via standard redux techniques

        if (!isLoggedIn) {
          const action = redirect({ type: 'LOGIN' })// action tells middleware to use history.replace()
          dispatch(action)                          // on the server you detect a redirect as done below
        }
      }
    }
  }

  const { reducer, middleware, enhancer, thunk } = connectRoutes(history, routesMap) 
  const rootReducer = combineReducers({ location: reducer })
  // enhancer first, then middleware
  const store = createStore(rootReducer, compose(enhancer, applyMiddleware(middleware)))

  // the idiomatic way to handle redirects
  // serverRender.js will short-circuit since the redirect is made here already
  let location = store.getState().location
  if (doesRedirect(location, res)) return false

  await thunk(store) // dont worry if your thunk doesn't return a promise

  // the idiomatic way to handle routes not found :)
  // your component's should also detect this state and render a 404 scene
  const status = location.type === NOT_FOUND ? 404 : 200
  res.status(status)

  return store
}

const doesRedirect = ({ kind, pathname, search }, res) => {
  if (kind === 'redirect') {
    res.redirect(302, search ? `${pathname}?${search}` : pathname); // the request completes here, therefore we must short-circuit after
    return true
  }
}

server/serverRender.js:

import ReactDOM from 'react-dom/server'
import { Provider } from 'react-redux'
import configureStore from './configureStore'
import App from './components/App'

export default async function serverRender(req, res) {
  const store = await configureStore(req, res) // pass res now too
  if (!store) return // no store means redirect was already served

  const appString = ReactDOM.renderToString(<Provider store={store}><App /></Provider>)
  const stateJson = JSON.stringify(store.getState())

  return res.send(
    `<!doctype html>
      <html>
        <body>
          <div id="root">${appString}</div>
          <script>window.REDUX_STATE = ${stateJson}</script>
          <script src="/static/main.js" />
        </body>
      </html>`
  )
}

Note: this example doubles as an example of how to use redirect in an SPA without SSR. thunk usage is the same whether you're doing SSR or not. You should be sharing the same routesMap between client and server code. You likely can share even more. The idiomatic approach is to create a shared src/configureStore.js file that does most of the work. Then in server/configureStore.js, handle the things that the client is NOT responsible for:

  • redirects
  • NOT_FOUND
  • global data-fetching
  • await thunk.

Note on Redirects

Why are redirect actions any different from regular actions?

To answer that question, imagine instead you pushed a URL on to the address bar for /login when the user tried to access a private area. Now imagine, the user presses the browser BACK button. The user will now be redirected back to login again and again. The user will struggle to go farther back in the history stack, which the user very well may want to do if he/she does not want to login at this time and just wants to get back to where he/she was at.

By using history.replace() behind the scenes, the private URL the user tried to access now becomes the /login URL in the stack, and the user can go back to the previous page just as he/she would expect.

On the server, this is another important anomaly because you don't want to render the /login page under the /private-area URL. The idiomatic way to handle that is the same as NOT_FOUND and therefore succinct and consistent.

Notes on NOT_FOUND

NOT_FOUND is no different than any action you can dispatch yourself. The only difference is that RFR also knows to dispatch it. It will be dispatched when no routes match the URL or if you dispatch an action that doesn't match a route path. Therefore it should be your catch-all action type to display a pretty page that shows the resource is missing.