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Server Side Rendering

Server Side Rendering (SSR) can improve the first-load performance of your application. Reactive Data Client takes this one step further by pre-populating the data store. Unlike other SSR methodologies, Reactive Data Client becomes interactive the moment the page is visible, making data mutations instantaneous. Additionally there is no need for additional data fetches that increase server load and slow client hydration, potentially causing application stutters.

NextJS SSR​

App Router​

NextJS 12 includes a new way of routing in the '/app' directory. This allows further performance improvements, as well as dynamic and nested routing.

Root Layout​

Place DataProvider in your root layout

app/layout.tsx
import { DataProvider } from '@data-client/react/nextjs';
import { AsyncBoundary } from '@data-client/react';

export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        <DataProvider>
          <header>Title</header>
          <AsyncBoundary>{children}</AsyncBoundary>
          <footer></footer>
        </DataProvider>
      </body>
    </html>
  );
}

Async Server Components anywhere between the provider and your Client Components are fine: the store is streamed to the browser alongside the HTML, so data fetched by a component that renders late still arrives before the HTML it produced. Every Suspense boundary then hydrates from exactly the data it was rendered with, without refetching.

app/[userId]/layout.tsx
export default async function UserLayout({ children, params }) {
  // resolves after the shell has already been sent
  const { userId } = await params;
  return <section data-user={userId}>{children}</section>;
}

Props​

interface NextDataProviderProps {
  children: ReactNode;
  managers?: () => Manager[];
  nonce?: string;
  Controller?: typeof Controller;
  gcPolicy?: GCInterface;
  devButton?: DevToolsPosition | null;
}

Controller applies on both server and client. gcPolicy applies in the browser only: a request-scoped server store has nothing to collect.

managers​

The server builds a store per request, so Managers must be created per request as well. It takes a function, called once per request on the server and once in the browser (the browser DataProvider accepts the same function; its array form is transitional):

app/Provider.tsx
'use client';
import { getDefaultManagers } from '@data-client/react';
import { DataProvider } from '@data-client/react/nextjs';

const managers = () => [...getDefaultManagers(), new MyManager()];

export default function Provider({ children }: { children: React.ReactNode }) {
  return <DataProvider managers={managers}>{children}</DataProvider>;
}

Manager instances shared across requests would mix up users' data, so an array is rejected. Server-side managers should not hold resources: their cleanup() is not run per request.

nonce​

State is streamed in inline <script> tags. When your Content Security Policy requires a nonce, pass it through:

app/layout.tsx
import { headers } from 'next/headers';
import { DataProvider } from '@data-client/react/nextjs';

export default async function RootLayout({ children }) {
  const nonce = (await headers()).get('x-nonce') ?? undefined;
  return (
    <html>
      <body>
        <DataProvider nonce={nonce}>{children}</DataProvider>
      </body>
    </html>
  );
}

Limitations​

  • Use one DataProvider per document. Nested or sibling providers share the same streamed state.
  • Only the initial document is transferred. Client-side navigations and router.refresh() fetch in the browser like any client render.
  • With Partial Prerendering the static shell's state is transferred; data fetched while resuming dynamic holes is fetched again in the browser.
  • If the same entity is returned with different data by two requests during one render, the browser hydrates with the latest one. Boundaries rendered from the earlier value are re-rendered by React (a recoverable hydration mismatch in development). Likewise, data the browser fetched on its own during streaming fills in anything the server never sent or removed, so a boundary the server rendered without that data is re-rendered with it.
  • On React 18 (including the version bundled with Next.js 13 and 14), a store update while a boundary is still hydrating - a streamed delta, a WebSocket manager, a mutation - can make React client-render that boundary. The data is still correct and nothing is refetched, but the server DOM nodes are replaced. React 19 keeps them and hydrates at a matching priority instead.

Client Components​

To keep your data fresh and performant, you can use client components and useSuspense()

app/todos/[userId]/page.tsx
'use client';
import { useSuspense } from '@data-client/react';
import { TodoResource } from '@/resources/Todo';

export default function InteractivePage({ params }: { params: { userId: number } }) {
  const todos = useSuspense(TodoResource.getList, params);
  return <TodoList todos={todos} />;
}

Note that this is identical to how you would write components without SSR. This makes makes the components usable across platforms.

Server Components​

However, if your data never changes, you can slightly decrease the javascript bundle sent, by using a server component. Simply await the endpoint:

app/todos/[userId]/page.tsx
import { TodoResource } from '@/resources/Todo';

export default async function StaticPage({ params }: { params: { userId: number } }) {
  const todos = await TodoResource.getList(params);
  return <TodoList todos={todos} />;
}

Demo​

More Demos

Class mangling and Entity.key​

NextJS will rename classes for production builds. Due to this, it's critical to define Entity.key as its default implementation is based on the class name.

class User extends Entity {
  id = '';
  username = '';

  static key = 'User';
}

Pages Router​

With NextJS < 14, you might be using the pages router. For this we have Document and NextJS specific wrapper for App

npm install --save @data-client/ssr @data-client/redux redux
pages/_document.tsx
import { DataClientDocument } from '@data-client/ssr/nextjs';

export default DataClientDocument;
pages/_app.tsx
import { AppDataProvider } from '@data-client/ssr/nextjs';
import type { AppProps } from 'next/app';

export default function App({ Component, pageProps }: AppProps) {
  return (
    <AppDataProvider>
      <Component {...pageProps} />
    </AppDataProvider>
  );
}
warning

When fetching from parameters from useRouter(), you will need to add getServerSideProps to avoid NextJS setting router.query to nothing

export default function MyComponent() {
  const id: string; = useRouter().query.id;
  const post = useSuspense(getPost, { id });
  // etc
}
export const getServerSideProps = () => ({ props: {} });

Further customizing Document​

To further customize Document, simply extend from the provided document.

Make sure you use super.getInitialProps() instead of Document.getInitialProps() or the Reactive Data Client code won't run!

pages/_document.tsx
import { Html, Head, Main, NextScript } from 'next/document';
import { DataClientDocument } from '@data-client/ssr/nextjs';

export default class MyDocument extends DataClientDocument {
  static async getInitialProps(ctx) {
    const originalRenderPage = ctx.renderPage;

    // Run the React rendering logic synchronously
    ctx.renderPage = () =>
      originalRenderPage({
        // Useful for wrapping the whole react tree
        enhanceApp: App => App,
        // Useful for wrapping in a per-page basis
        enhanceComponent: Component => Component,
      });

    // Run the parent `getInitialProps`, it now includes the custom `renderPage`
    const initialProps = await super.getInitialProps(ctx);

    return initialProps;
  }

  render() {
    return (
      <Html>
        <Head />
        <body>
          <Main />
          <NextScript />
        </body>
      </Html>
    );
  }
}

CSP Nonce​

Reactive Data Client Document serializes the store state in a script tag. In case you have Content Security Policy restrictions that require use of a nonce, you can override DataClientDocument.getNonce.

Since there is no standard way of handling nonce in NextJS, this allows you to retrieve any nonce you created in the DocumentContext to use with Reactive Data Client.

pages/_document.tsx
import { DataClientDocument } from '@data-client/ssr/nextjs';
import type { DocumentContext } from 'next/document.js';

export default class MyDocument extends DataClientDocument {
  static getNonce(ctx: DocumentContext & { res: { nonce?: string } }) {
    // this assumes nonce has been added here - customize as you need
    return ctx?.res?.nonce;
  }
}

Express JS SSR​

When implementing your own server using express.

Server side​

import express from 'express';
import { renderToPipeableStream } from 'react-dom/server';
import {
  createPersistedStore,
  createServerDataComponent,
} from '@data-client/react/ssr';

const rootId = 'react-root';

const app = express();
app.get('/*', (req: any, res: any) => {
  const [ServerDataProvider, useReadyCacheState, controller] =
    createPersistedStore();
  const ServerDataComponent =
    createServerDataComponent(useReadyCacheState);

  controller.fetch(NeededForPage, { id: 5 });

  const { pipe, abort } = renderToPipeableStream(
    <Document
      assets={assets}
      scripts={[<ServerDataComponent key="server-data" />]}
      rootId={rootId}
    >
      <ServerDataProvider>{children}</ServerDataProvider>
    </Document>,

    {
      onCompleteShell() {
        // If something errored before we started streaming, we set the error code appropriately.
        res.statusCode = didError ? 500 : 200;
        res.setHeader('Content-type', 'text/html');
        pipe(res);
      },
      onError(x: any) {
        didError = true;
        console.error(x);
        res.statusCode = 500;
        pipe(res);
      },
    },
  );
  // Abandon and switch to client rendering if enough time passes.
  // Try lowering this to see the client recover.
  setTimeout(abort, 1000);
});

app.listen(3000, () => {
  console.log(`Listening at ${PORT}...`);
});

Client​

import { hydrateRoot } from 'react-dom';
import { awaitInitialData } from '@data-client/react/ssr';

const rootId = 'react-root';

awaitInitialData().then(initialState => {
  hydrateRoot(
    document.getElementById(rootId),
    <DataProvider initialState={initialState}>{children}</DataProvider>,
  );
});