react-network

@shopify/react-network

A collection of components that allow you to set common HTTP headers from within your React application.

Installation

$ yarn add @shopify/react-network

Usage

This package uses @shopify/react-effect to allow your application to communicate various HTTP-related details to the Node server doing React rendering. It also provides a utility function for easily applying these details to a Koa context object.

Application

This library provides a number of React hooks and components you can use anywhere in your application to register network-related details on the server.

useRedirect() and <Redirect />

Specifies a redirect location. applyToContext will call ctx.redirect() with the passed URL, and set the status code, if you pass the code prop.

import {useRedirect, Redirect, StatusCode} from '@shopify/react-network';

function MyComponent() {
  useRedirect('/login', StatusCode.SeeOther);

  // or
  return <Redirect url="/login" code={StatusCode.SeeOther} />;
}

useStatus() and <Status />

Specifies a status code. applyToContext will set ctx.status with the passed status code. If multiple status codes are set during the navigation of the tree, the most "significant" one will be used — that is, the status code that is the highest numerically.

import {useStatus, Status, StatusCode} from '@shopify/react-network';

function MyComponent() {
  useStatus(StatusCode.NotFound);

  // or

  return <Status code={StatusCode.SeeOther} />;
}

useCspDirective() and content security policy components

This package exports a useCspDirective() hook (and many components) for constructing a content security policy (CSP). Every CSP directive has a matching component in this library that exposes a nice API for setting that directive. When applyToContext is run, it will group together all of the directives and set the CSP header.

There are too many to go over individually, but the example below illustrates setting up a simple CSP. Review the available imports from the library for all available components.

import {
  useCspDirective,
  DefaultSource,
  StyleSource,
  SpecialSource,
  CspDirective,
  UpgradeInsecureRequests,
} from '@shopify/react-network';

export default function ContentSecurityPolicy() {
  useCspDirective(CspDirective.DefaultSrc, [SpecialSource.Self]);
  useCspDirective(CspDirective.StyleSrc, [
    SpecialSource.Self,
    SpecialSource.UnsafeInline,
  ]);
  useCspDirective(CspDirective.UpgradeInsecureRequests, true);

  // OR

  return (
    <>
      <DefaultSource sources={[SpecialSource.Self]} />
      <StyleSource sources={[SpecialSource.Self, SpecialSource.UnsafeInline]} />
      <UpgradeInsecureRequests />
    </>
  );
}

useHeader() and useRequestHeader()

This library allows you to read from request headers, and set response headers. To set a header, call the useHeader() hook, which accepts the name of a header and the desired value. useRequestHeader(), on the other hand, gives you access to a specified request header.

Note: calling useRequestHeader on client-side renders will give you undefined, since we only have access to the request context on the server. To remedy this, wrap your app in a NetworkUniversalProvider (see below for more details).

import {useHeader, useRequestHeader} from '@shopify/react-network';

function MyComponent() {
  useHeader('X-React', 'true');
  const acceptLanguage = useRequestHeader('Accept-Language');
  return <div>Requested languages: {acceptLanguage}</div>;
}

useAcceptLanguage()

This hook will read and parse the value of the Accept-Language header and return the result in an array of Language objects. It takes one argument as the fallback Language in case the header is not present.

Note: useAcceptLanguage calls useRequestHeader, so the constraints on client-side renders apply here too. Wrap your app in a NetworkUniversalProvider and pass in [Header.AcceptLanguage] to the headers prop in order to call useAcceptLanguage on subsequent client-side renders.

import {useAcceptLanguage} from '@shopify/react-network';

function MyComponent() {
  const fallback = {code: 'en', quality: 1.0};
  const locales = useAcceptLanguage(fallback);

  const languages = locales.map(({code, quality, region}) => {
    return `code: ${code}, quality: ${quality}, region: ${region}`;
  });

  return <div>Requested languages: {languages}</div>;
}

useNetworkManager()

Returns the full network manager from context.

import React from 'react';
import {useNetworkManager} from '@shopify/react-network';
import {CookieContext} from './context';

export function CookieProvider({children}: Props) {
  const manager = useNetworkManager();

  return (
    <CookieContext.Provider value={manager.cookies}>
      {children}
    </CookieContext.Provider>
  );
}

<NetworkUniversalProvider />

In the case you need to have access to network details on both client and server-side renders, you can wrap your top-level app in NetworkUniversalProvider like so:

export default function App() {
  return (
    <NetworkUniversalProvider
      headers={['x-some-header', 'x-some-other-header']}
    >
      {
        // rest of your app
      }
    </NetworkUniversalProvider>
  );
}

Note that NetworkContext.Provider has to be rendered somewhere above in your app (see below).

Currently this universal provider only supports headers, so you can pass in an array of header names to the headers prop. Then, in components nested further down in your tree you can get those headers from context using useRequestHeader on client-side renders like so:

export default function SomeInnerComponent() {
  const someHeaderValue = useRequestHeader('x-some-header');
  const someOtherHeaderValue = useRequestHeader('x-some-other-header');

  return (
    <Markup
      value={someHeaderDependentLogic(someHeaderValue, someOtherHeaderValue)}
    />
  );
}

headers aren't case-sensitive, but it's a good idea to keep consistent between NetworkUniversalProvider and useRequestHeader.

Server

To extract details from your application, render a NetworkContext.Provider around your app, and give it an instance of NetworkManager. When using react-effect, this decoration can be done in the decorate option of extract(). Finally, you can use the applyToContext utility from this package to apply the necessary headers to the response. Your final server middleware will resemble the example below:

import React from 'react';
import {render} from '@shopify/react-html/server';
import {extract} from '@shopify/react-effect/server';
import {
  NetworkManager,
  NetworkContext,
  applyToContext,
} from '@shopify/react-network/server';
import App from './App';

export default function renderApp(ctx: Context) {
  // Accepts an optional headers argument for giving access
  // to request headers.
  const networkManager = new NetworkManager({
    headers: ctx.headers,
  });

  const app = <App />;

  await extract(app, {
    decorate: element => (
      <NetworkContext.Provider value={networkManager}>
        {element}
      </NetworkContext.Provider>
    ),
  });

  applyToContext(ctx, networkManager);
  ctx.body = render(
    <NetworkContext.Provider value={networkManager}>
      {app}
    </NetworkContext.Provider>,
  );
}

Note: You can selectively extract only the network details by using the EFFECT_ID exported from @shopify/react-network/server, and using this as the second argument to @shopify/react-effect’s extract() as detailed in its documentation. Most consumers of this package will be fine with just the example above.

Other utilities

This library re-exports the entirety of @shopify/network, so you do not need to install both.