Centarius

Like AfterJS but more customizable

Inspired from AfterJS and React Router Config

Getting started with Centarius

Centarius has same API as After.js.

If you have familiarize yourself with After, then you are not finding it difficult to migrate to Centarius.

Also : You can build it on your SSR boilerplate (either it webpack, parcel, etc).

Centarius is just another component wrapper to ease React SSR.

Quickstart with Razzle

curl https://codeload.github.com/rayandrews/centarius/tar.gz/master | tar -xz --strip=2 centarius-master/examples/basic
cd basic

---

Background

AfterJS is awesome library but it has some drawbacks that I found it difficult to modify it in my other projects such as :

• Routes' config only one level depth, and

• Not able to modify routes config as we wish, imagine you are building complex application's routes. Sometimes just map over through your routes' config and get initial props are not enough.

• Some routes are using same logical needs. We need strategy for providing it.

We need to adopt and a little bit to modify React Router Config strategy in our apps, to make more complex and declarative application based on routes config

• Not able to modify static method for get initial props (getInitialProps is good, but you should be able to modify the name based on your content)

• Not able to handle loading or error state while transitioning and getting initial props for other route

---

Table of Contents

• How Centarius Works
• Data Fetching
  • getInitialProps | { name } : (ctx) => object
  • Injected Context Data
• Routing
• Custom Options
• Code Splitting
• Custom Document
• Custom/Async Rendering
• Authors
• Special Thanks
• Inspirations
• License

---

How Centarius Works

Centarius will read through your routes' config to find component that you've already specified.

Data Fetching

In all components that you want to passed the initial data, you can add a static async getInitialProps or another function's name that exactly does the same.

This will be called on both initial server render and while transitioning between routes.

Results are made available on the props

// Home.js
import React from 'react';
import { NavLink } from 'react-router-dom';

class Home extends React.Component {
  static async getInitialProps({ req, res, match }) {
    const stuff = await CallMyApi();
    return { stuff }; // returned value from static method not passed on props by default
  }

  render() {
    return (
      <div>
        <NavLink to="/about">About</NavLink>
        <h1>Home</h1>
      </div>
    );
  }
}

export default Home;

getInitialProps | { name } : (ctx) => object

Within getInitialProps or another function name, you will get access to all you need to fetch data on both the client and the server (same like After)

• req?: Request object: (server-only) A Express.js request object
• res?: Request object: (server-only) An Express.js response object
• match: object: React Router 4's match object.
• history: object: React Router 4's history object.
• location: object: (client-only) React Router 4's location object.
• isServer: boolean: Check whether code is running on server or client
• query: object: Parsed query string from url
• params: object: Parsed param object from React Router

You can also add another variable to be passed into static method like Redux Store, etc.

If you are using some server only modules inside getInitialProps or anoher function name, make sure to import them properly. Otherwise, it'll slow down your app.

Taken from Next

Injected Page Props

• Whatever you have returned in getInitialProps
• prefetch: (pathname: string) => void - Imperatively prefetch and cache data for a path.

// Home.js
import React from 'react';
import { NavLink } from 'react-router-dom';
import { CentariusConsumer } from 'centarius/core';

class Home extends React.Component {
  static async getInitialProps({ req, res, match }) {
    const stuff = await CallMyApi();
    return { stuff };
  }

  render() {
    return (
      <div>
        <NavLink to="/about">About</NavLink>
        <h1>Home</h1>
        <div>{this.props.stuff || ''}</div>
      </div>
    );
  }
}

export default Home;

Routing

React Router 4 is used in all over Centarius API.

Parameterized Routing

// ./src/routes.js
import Home from './Home';
import About from './About';
import Counter from './Counter';

// Internally these will become:
// <Route path={path} exact={exact} render={props => <component {...props} data={data} />} />
const routes = [
  {
    path: '/',
    exact: true,
    component: Home,
  },
  {
    path: '/about',
    component: About,
  },
  {
    path: '/counter/:count',
    component: Counter,
  },
];

export default routes;

Custom Route Component

Sometimes you need to modify the route component for your needs such as Protected Route to handle your system's authentication. Centarius provides you with a simple solution for this by using attribute routerComponent in your routes config

// ./src/routes.js
import Home from './Home';
import User from './User';
import About from './About';
import Counter from './Counter';

import ProtectedRoute from './ProtectedRoute';

const routes = [
  {
    path: '/',
    exact: true,
    component: Home,
  },
  {
    path: '/user/:username',
    routeComponent: ProtectedRoute,
    component: User,
    ...rest

    // Internally these will become:
    // <ProtectedRoute path={path} exact={exact} render={props => <component {...props} data={data} />} {...rest } />
  },
  {
    path: '/about',
    component: About,
  },
  {
    path: '/counter/:count',
    component: Counter,
  },
];

export default routes;

Nested Route

Sometimes you need to nested your routes to handle so many things.

---

However, you need to make parent component render children component.

TL;DR : path will be concatted recursively from parent routes

{
  path: '/user',
  exact: true,
  routeComponent: ProtectedRoute,
  component: User,
  routes: [
    {
      path: '/:username',
      component: UserDetail,
      exact: true,
      routes: [
        {
          path: '/edit',
          component: UserEdit,
        }
      ]
    },
  ],
  ...rest
}

That code will make /user/:username render UserDetail component and user/:username/edit will render UserEdit component.

---

// ./src/routes.js
import Home from './Home';

import User from './User';
import UserDetail from './UserDetail';

import About from './About';
import Counter from './Counter';

import ProtectedRoute from './ProtectedRoute';

const routes = [
  {
    path: '/',
    exact: true,
    component: Home,
  },
  {
    path: '/user',
    exact: true,
    routeComponent: ProtectedRoute,
    component: User,
    routes: [
      {
        path: '/:username',
        component: UserDetail,
      },
    ],
    ...rest

    // Internally these will become:
    //
    // <ProtectedRoute
    //    path="/user"
    //    exact
    //    render={props =>
    //      <User {...props} data={data}>
    //        <Route
    //          path="/user/:username"
    //          render={childrenProps =>
    //            <UserDetail {...props} data={data} />
    //          }
    //        />
    //      </User>
    //    }
    //    {...rest }
    //  />
  },
  {
    path: '/about',
    component: About,
  },
  {
    path: '/counter/:count',
    component: Counter,
  },
];

export default routes;

Custom Options

Examples

• Redux RNW React Loadable
• Redux RNW Loadable Components

Centarius has default options as follows

{
  document: React.Component<any, any> = DefaultCentariusDocument,
  staticMethod: string = 'getInitialProps',
  rootId: string = 'root',
  dataId: string = 'server-app-state',
  isServer: boolean,

  routes: Array<RouteObject> = [], // override this!
}

If you want to change static method, rootId, and dataId, you must pass it both in client and server

Example

Centarius : ({ routes, data, options, beforeNavigating, afterNavigating }) => React.Component<any, any>

• routes: array[]: Routes config
• data: object: Initial data for Centarius
• options: object: Centarius custom options
• beforeNavigating: () => void: (client-only) Function that runs before navigating between route
• afterNavigating: ()=> void: (client-only) Function that runs after navigating between route

// client.js

import React from 'react';
import { hydrate } from 'react-dom';
import { BrowserRouter } from 'react-router-dom';
import './client.css';

import { Centarius } from 'centarius/core';
import { getSsrData } from 'centarius/client';
import routes from './routes';

const data = getSsrData();
const options = {
  staticMethod: 'fetchData', // * change the method to make client can preload data

  // Anything else you add here will be made available
  // within static method in client
  // e.g a redux store, etc.
}

hydrate(
  <BrowserRouter>
    <Centarius routes={routes} data={data} options={options} />
  </BrowserRouter>,
  document.getElementById('root')
);

if (module.hot) {
  module.hot.accept();
}

render : (options: object) => html : string

// server.js

import express from 'express';
import { render } from 'centarius/server';

import routes from './routes';

const assets = require(process.env.RAZZLE_ASSETS_MANIFEST);

const server = express();
server
  .disable('x-powered-by')
  .use(express.static(process.env.RAZZLE_PUBLIC_DIR))
  .get('/*', async (req, res) => {
    const routerContext = {};

    if (req.url.match(/.map$/)) return;

    try {
      const html = await render({
        req,
        res,
        routes,
        assets,
        staticMethod: 'fetchData',
        customThing: 'thing',

        // Anything else you add here will be made available
        // within static method in server
        // e.g a redux store, etc.
      });
      res.send(html);
    } catch (error) {
      res.json(error);
    }
  });

export default server;

Code Splitting

Examples

• Loadable Components with React Native Web and Redux
• React Loadable with React Native Web and Redux

Centarius does not defining any code splitting method like After, Next, or Rogue (with loadable-components) did.

But Centarius does enforce you to implement code splitting with other libraries

With the right custom routes config, you can implement it with another React code splitting library out there such as

• React Loadable
• Loadable Components

Currently, Centarius only suppors code splitting library that has static method [load | preload] that return component and also hoisting static method such as getInitialProps after it has been loaded.

Custom Document

Examples

• Basic with React Native Web
• Loadable Components with React Native Web and Redux
• React Loadable with React Native Web and Redux

Centarius works like After and Next, you can override any html structure that suitable for your needs.

Why we need it?

Centarius does not support React Helmet by default, you must add it on your document and custom render.

It really helps if you want to add CSS or other component with side-effects (React Helmet, etc) that needs custom document structure.

Example with React Helmet and React Native Web

// document.js

import React, { Component } from 'react';
import { AppRegistry } from 'react-native';
import { renderToStaticMarkup } from 'react-dom/server';

import { CentariusRoot, CentariusData } from 'centarius/document';

/* eslint-disable */

export default class CustomDocument extends Component {
  static async getInitialProps({ assets, data, renderPage }) {
    const page = await renderPage();

    return { assets, data, ...page };
  }

  render() {
    const {
      rootId,
      dataId,
      data,

      // we passed it via custom renderer
      assets,
      helmet,
      rnwCss,
    } = this.props;

    const htmlAttrs = helmet.htmlAttributes.toComponent();
    const bodyAttrs = helmet.bodyAttributes.toComponent();

    return (
      <html lang="en" {...htmlAttrs}>
        <head>
          <meta httpEquiv="X-UA-Compatible" content="IE=edge" />
          <meta charSet="utf-8" />
          <meta name="viewport" content="width=device-width, initial-scale=1" />
          {helmet.title.toComponent()}
          {helmet.meta.toComponent()}
          {helmet.link.toComponent()}
          {assets.client.css && (
            <link rel="stylesheet" href={assets.client.css} />
          )}
          <style
            id="react-native-stylesheet"
            dangerouslySetInnerHTML={{
              __html: rnwCss
                .replace(/<\/style>/g, '')
                .replace(/<style id="react-native-stylesheet">/g, ''),
            }}
          />
        </head>
        <body {...bodyAttrs}>
          <CentariusRoot id={rootId} />
          <CentariusData id={dataId} data={data} />
          <script
            type="text/javascript"
            src={assets.client.js}
            crossOrigin="anonymous"
          />
        </body>
      </html>
    );
  }
}

// server.js

import express from 'express';

import React, { Fragment } from 'react';
import { renderToString, renderToStaticMarkup } from 'react-dom/server';
import { AppRegistry } from 'react-native';
import Helmet from 'react-helmet';

import { render } from 'centarius/server';

import document from './document';

import routes from './routes';

const assets = require(process.env.RAZZLE_ASSETS_MANIFEST);

const server = express();
server
  .disable('x-powered-by')
  .use(express.static(process.env.RAZZLE_PUBLIC_DIR))
  .get('/*', async (req, res) => {
    if (req.url.match(/.map$/)) return;

    try {
      const customRenderer = async (node) => {
        const helmet = Helmet.renderStatic();

        const CustomApp = () => <Fragment>{node}</Fragment>;

        AppRegistry.registerComponent('App', () => CustomApp);

        const { element, getStyleElement } = AppRegistry.getApplication(
          'App',
          {}
        );

        return {
          helmet,
          rnwCss: renderToStaticMarkup(getStyleElement()),
          html: renderToString(element),
        };
      };

      const html = await render({
        req,
        res,
        routes,
        assets,
        document,
        customRenderer,
        customThing: 'thing',
      });

      if (res.finished) return;

      res.send(html);
    } catch (error) {
      res.status(500);
      res.send(error.stack);
    }
  });

export default server;

If you were using something like styled-components, and you need to wrap you entire app with some sort of additional provider or function, you can do this with renderPage().

Taken from After

// Document.js
import React, { Component } from 'react';
import { ServerStyleSheet } from 'styled-components'
import { renderToStaticMarkup } from 'react-dom/server';

import { CentariusRoot, CentariusData } from 'centarius/document';

export default class CustomDocument extends Component {
  static async getInitialProps({ assets, data, renderPage }) {
    const sheet = new ServerStyleSheet();
    const page = await renderPage(App => props => sheet.collectStyles(<App {...props} />));
    const styleTags = sheet.getStyleElement();
    return { assets, data, ...page, styleTags };
  }

  render() {
    const {
      rootId,
      dataId,
      helmet,
      assets,
      data,
      styleTags,
    } = this.props;

    return (
      <html lang="en">
        <head>
          <meta httpEquiv="X-UA-Compatible" content="IE=edge" />
          <meta charSet="utf-8" />
          <meta name="viewport" content="width=device-width, initial-scale=1" />
          {styleTags}
        </head>
        <body>
          <CentariusRoot id={rootId} />
          <CentariusData id={dataId} data={data} />
          <script
            type="text/javascript"
            src={assets.client.js}
            defer
            crossOrigin="anonymous"
          />
        </body>
      </html>
    );
  }

To use custom document, you need to pass it on server file

// server.js

import express from 'express';
import { render } from 'centarius/server';

import routes from './routes';
import Doc from './Document';

const assets = require(process.env.RAZZLE_ASSETS_MANIFEST);

const server = express();
server
  .disable('x-powered-by')
  .use(express.static(process.env.RAZZLE_PUBLIC_DIR))
  .get('/*', async (req, res) => {
    if (req.url.match(/.map$/)) return;

    try {
      const html = await render({
        req,
        res,
        assets,
        staticMethod: 'fetchData',
        customThing: 'thing',
        document: Doc,
        // Anything else you add here will be made available
        // within static method in server
        // e.g a redux store, etc.
      });
      res.send(html);
    } catch (error) {
      res.json(error);
    }
  });

export default server;

Custom/Async Rendering

Examples

• Loadable Components with React Native Web and Redux
• React Loadable with React Native Web and Redux

You can provide a custom (potentially async) rendering function as an option to Centarius render function, just like After.js.

If it presents, it will be used instead of the default ReactDOMServer renderToString function.

It has to return an object of shape { html : string!, ...otherProps }, in which html will be used as the rendered string.

otherProps will be passed as props to the rendered Document.

defaultRenderer = (node) => ({ html: ReactDOMServer.renderToString(node) })

Example

// server.js

import express from 'express';
import { render } from 'centarius/server';

import { Capture } from 'react-loadable';
import { getBundles } from 'react-loadable/webpack';

import stats from 'build/react-loadable.json';

import configureStore from 'store/configureStore';

import routes from './routes';
import Doc from './Document';

const assets = require(process.env.RAZZLE_ASSETS_MANIFEST);

const server = express();
server
  .disable('x-powered-by')
  .use(express.static(process.env.RAZZLE_PUBLIC_DIR))
  .get('/*', async (req, res) => {
    if (req.url.match(/.map$/)) return;

    try {
      const preloadedState = {};
      const store = configureStore(preloadedState);
      const modules = [];

      const customRenderer = (node) => {
        const CustomApp = (
          <Capture report={(moduleName) => modules.push(moduleName)}>
            <Provider store={store}>{node}</Provider>
          </Capture>
        );

        const bundles = getBundles(stats, modules);
        const chunks = bundles.filter((bundle) => bundle.file.endsWith('.js'));

        return {
          chunks,
          store, // notice that this will passed into document
          html: renderToString(CustomApp),
        };
      };

      const html = await render({
        req,
        res,
        routes,
        assets,
        staticMethod: 'fetchData',
        customThing: 'thing',
        document: Doc,
        store, // this will be passed in static method in server

        // Anything else you add here will be made available
        // within static method in server
        // e.g a redux store, etc.
      });
      res.send(html);
    } catch (error) {
      res.json(error);
    }
  });

export default server;

Packages / Plugins / Addons / HOCs

Package	Version	Dependencies	Description
centarius			Core package. Required
@centarius/state-hoc			State HOC for Centarius
@centarius/react-loadable			React Loadable HOC for Centarius

---

Authors

• Ray Andrew @rayandrews
• Natan Elia @natanelia

---

Special Thanks

• Jared Palmer @jaredpalmer for After.JS
• Ivana Irene @ivanaairenee
• Reinaldo Ignatius @nimitz21

---

Inspirations

• Next.js
• After.js
• Rogue.js
• Razzle

---

License

This project is licensed under the MIT License - see the LICENSE.md file for details