Generate a PDF in Remix with Resource Routes

Remix has a feature called Resource Routes which let you create endpoints returning anything.

Using them, you could return a Response with a PDF, how to generate the PDF will depend on what libraries you are using, if you use something like React PDF you could do something like this:

// routes/pdf.tsx
import { renderToStream } from "@react-pdf/renderer";
// this is your PDF document component created with React PDF
import { PDFDocument } from "~/components/pdf";
import type { LoaderFunction } from "remix";

export let loader: LoaderFunction = async ({ request, params }) => {
  // you can get any data you need to generate the PDF inside the loader
  // however you want, e.g. fetch an API or query a DB or read the FS
  let data = await getDataForThePDFSomehow({ request, params });

  // render the PDF as a stream so you do it async
  let stream = await renderToStream(<PDFDocument {...data} />);

  // and transform it to a Buffer to send in the Response
  let body: Buffer = await new Promise((resolve, reject) => {
    let buffers: Uint8Array[] = [];
    stream.on("data", (data) => {
      buffers.push(data);
    });
    stream.on("end", () => {
      resolve(Buffer.concat(buffers));
    });
    stream.on("error", reject);
  });

  // finally create the Response with the correct Content-Type header for
  // a PDF
  let headers = new Headers({ "Content-Type": "application/pdf" });
  return new Response(body, { status: 200, headers });
}

Now when the user goes to /pdf it will get the PDF file back, you could also use an iframe to show it on the HTML.

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If you don't use React PDF, change the render part to use the library you are using, and keep the headers and the Response creation part.