compat with react 19

[joacub]

React pdf is not compatible with react 19, will you make the library compat with this version ?

[joacub]

👀

[ZipBrandon]

Anything @eps1lon you can suggest? I have been poking around in the react-reconciler but it has drifted and largely undocumented.

[eps1lon]

react-three-fiber also had to update its reconciler implementation. One of the breaking changes that was hard to track down was around commitUpdate which is no longer called with an updatePayload.

Where is the code for the reconciler implementation? Maybe something stands out to me. But no promises for now since we're not using that library at Vercel.

[ZipBrandon]

@eps1lon Here is where @diegomura creates the reconciler. When I updated the deps on my fork, I couldn't get the document to be created from the updateContainer call here

[joacub]

Some advances ?

[ZipBrandon]

FWIW I have patched my version to use React 18. I only use the node version of the renderer so having a version of react@18.3.1 that is only used for that suits my purpose.

I'm aliasing react-18 with "react-18": "npm:react@^18.3.1" in my package.json.

This uses a patch I made with patch-package where the renderer code thenimport React from "react-18".

I had to use the escape hatch of "use no memo" in my components to opt-out the compiler.

I use the pragma /** @jsxImportSource react-18 */ at the top of all files that are associated with the PDF rendering so it goes through the correct createElement().

That being said, this is just duct tape to get by until we have true React 19 compatability.

[cipriancaba]

That's a very interesting aproach @ZipBrandon but I feel like vercel and react will need to come up with a better solution than this since any 3rd party lib you might be using that is not updated will simply prevent you from upgrading to next 15 and react 19.

What is the suggested path here @eps1lon ? I've spent the time migrating to next 15, loved the wait everything felt until one of our agents told me the pdf generation page was buggered so had to revert to latest stable next

[cipriancaba]

Hi @ZipBrandon , do you mind sharing the patch you used to make this work?

[eps1lon]

I don't see what else we can do. This is just inherent to breaking changes in a library.

What is the suggested path here @eps1lon ?

The suggested path for libraries to ensure compatibility during the alpha period which we announced on the 25th of April. But we also encourage libraries to ensure continuous compatibility by regularly testing Canary.

But we also spent resources at Vercel to ensure the libraries are compatible we use:

• Externalize JSX runtime uiwjs/react-codemirror#655
• 2.x: Support react 19 recharts/recharts#4542
• Ensure maximum compatibility with mdx-bundler timlrx/contentlayer2#19
• Use useId instead of React internals tailwindlabs/headlessui#3254
• fix(@react-email/tailwind): Treat React as a peer dependency resend/react-email#1463
• fix: Use scoped JSX namespace vercel/styled-jsx#846
• fix(@react-email/tailwind): Stop inlining JSX runtime resend/react-email#1462
• Use new JSX runtime pmndrs/react-three-fiber#3256
• feat: Add support for React 19 Canary testing-library/react-testing-library#1294

or helped these libraries when upgrading:

• React 19 compatibility radix-ui/primitives#2934
• Fix missing act warnings issued from focus and blur calls tailwindlabs/headlessui#3253
• [v9] fix!: upgrade reconciler for React 19 pmndrs/react-three-fiber#3224 (comment)

This is a community effort though so we need all the help we can get

[cipriancaba]

Thanks for the reply @eps1lon and your efforts are obviously much appreciated

I've been tracking your issue here eps1lon/react#10

I guess when I meant suggested path I meant more like this is literally a blocker for any kind of upgrade to react 19 / next 15. Is there potential for a more generic temporary fix (maybe similar to what @ZipBrandon suggested) until react 19 is fully adopted by lib authors? In every real life project there's this obscure library that you absolutely have to use and then if that blocks your entire upgrade path, you're basically stuck.

[ZipBrandon]

@cipriancaba Sure! Here's the the gist of the patch for @react-pdf/renderer https://gist.github.com/ZipBrandon/b6c3848a400feff9741d739b7544d4fe. This is only for rendering on the Node side. I didn't do anything for browser rendering.

Caveats to remember:

• "react-18": "npm:react@^18.3.1", in your package.json deps.
• /** @jsxImportSource react-18 */ at the top of any of your files that are React components that are being rendered in the PDF. You should not have React 19 and React 18 components in the same file.
• Import anything you need in those components from React from "react-18" package.
• If using the React Compiler, opt-out in the PDF components with "use no memo"

[alexandernanberg]

I've done some investigations and the library is incompatible with react-reconciler 0.27.0 and later (React 19 requires ^0.31.0).

The library expect reconciler.createContainer to mutate the document property of the container.

react-pdf/packages/renderer/src/index.js

Lines 26 to 28 in f64f3bd

	const container = { type: 'ROOT', document: null };
	renderer = renderer || createRenderer({ onChange });
	const mountNode = renderer.createContainer(container);

which is then accessed here

react-pdf/packages/renderer/src/index.js

Lines 37 to 38 in f64f3bd

	const props = container.document.props || {};
	const { pdfVersion, language, pageLayout, pageMode } = props;

In 0.27.0 the container.document is always null

I've tried finding workarounds, but I'm not familiar with the internals of the reconciler. @eps1lon thankful for any pointers!

Edit:

Seems like newer version of the reconciler forces the container to be immutable, or that it clones the object passed into createContainer. The mutation part is done in appendChildToContainer

react-pdf/packages/renderer/src/renderer.js

Lines 103 to 109 in f64f3bd

	appendChildToContainer(parentInstance, child) {
	if (parentInstance.type === 'ROOT') {
	parentInstance.document = child;
	} else {
	appendChild(parentInstance, child);
	}
	},

Edit 2:

Okay so looks like updateContainer now schedules an update instead of doing it sync. And library code relies on the sync behavior.

  const updateContainer = (doc, callback) => {
    renderer.updateContainer(doc, mountNode, null, callback);
  };

  if (initialValue) updateContainer(initialValue);

  setTimeout(() => {
    console.log(container);
	// container.document is set now
  }, 0);