centarius

Centarius

If AfterJS and RogueJS had a baby...



NextJS beloved grandchild..

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

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

• Not able to modify routes tree
• 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 add loading or error component while transitioning and getting initial props for other route
• Code splitting and load inital props based on routes config

---

How about Rogue?

Brilliant Idea to walk into react tree component recursively like Apollo did in their library

But.. something is bothering me..

• Document feature in Next and After is REALLY syntactic sugar
• GetInitialProps method only called on top highest level component (for performance, I know)
• And of course, not be able to modify static method too

tl;dr
I found them not too suitable for my works

---

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
• Custom/Async Rendering
• Authors
• Special Thanks
• Inspirations
• License

---

How Centarius Works

Centarius will walk through your React Tree to find static method that you've already specified.

If Centarius not found any static method, Centarius will gracefully return your rendered component.

Data Fetching

For now, in all components that you want to fetch, 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 then client mounts.

Results are made available on the CONTEXT NOT ON PROPS

If you want to get data in the props, you must include the centariusHoc to easily passing data from context to props.

OR

Use CentariusConsumer (React ^16) to consume the data.

// 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: (server-only) A Express.js request object
• res?: Request: (server-only) An Express.js response object
• match: React Router 4's match object.
• history: React Router 4's history object.
• location: (client-only) React Router 4's location object.
• isServer: Check whether code is running on server or client

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 Context Data

• data: any - Whatever you have returned in getInitialProps or another function name
• loading: boolean - Loading state while fetching data in client
• error: boolean - Error state (but not throwing error) while fetching data in client
• 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>
        <CentariusConsumer>
          {({ data, loading }) => (
            if(loading) return <div>'Loading...'</div>;

            return data.stuff;
          )}
        </CentariusConsumer>
      </div>
    );
  }
}

export default Home;

OR

Using centariusHoc to wrap your context into props, just like Redux connect.

You can also pass options like LoadingComponent and ErrorComponent to reduce boilerplate in your render function.

centariusHoc : ({ LoadingComponent?: null, ErrorComponent?: null }) => (Component) => WrappedComponent

TL;DR All static methods will be hoisted

// Home.js
import React from 'react';
import { NavLink } from 'react-router-dom';
import centariusStateHoc from '@centarius/state-hoc'

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.data.stuff}</div>
      </div>
    );
  }
}

export default centariusHoc({
  LoadingComponent: () => <div>Loading...</div>,
  ErrorComponent: () => <div>Error!</div>
})(Home);

Routing

React Router 4 is used in all over Centarius API.

Custom Options

Examples

• Basic with React Native Web

Centarius does not need any router config, so just passing React component with React Router 4 in it, and you're done!

Centarius has default options as follows

{
  document = DefaultCentariusDocument,
  staticMethod = 'getInitialProps',
  rootId = 'root',
  dataId = 'server-app-state',
}

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

Example

Centarius : ({ component, data, options }) => RenderedComponent

// 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 App from './App';

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 component={App} data={data} options={options} />
  </BrowserRouter>,
  document.getElementById('root')
);

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

render : (component = App, routerContext, options) => html : string

// server.js

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

import App from './App';

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(App, routerContext, {
        req,
        res,
        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 render function, you can implement it with another React code splitting library out there such as

• React Loadable
• Loadable Components

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?

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 Native Web

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();

    AppRegistry.registerComponent('CentariusRoot', () => CentariusRoot);
    const { getStyleElement } = AppRegistry.getApplication('CentariusRoot', {});

    const rnwCss = renderToStaticMarkup(getStyleElement());

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

  render() {
    const {
      rootId,
      dataId,
      helmet,
      assets,
      data,
      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>
    );
  }
}

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;
    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()}
          {styleTags}
        </head>
        <body {...bodyAttrs}>
          <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 App from './App';
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) => {
    const routerContext = {};

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

    try {
      const html = await render(App, routerContext, {
        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 App from './App';
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) => {
    const routerContext = {};

    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(App, routerContext, {
        req,
        res,
        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;

---

Authors

• Ray Andrew @rayandrews
• Natan Elia @natanelia

---

Special Thanks

• 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