SvelteKit / receipts
Receipt PDFs in SvelteKit
Post your receipt HTML to a render API from a +server.ts endpoint returning a Response, then return a Response built from the upstream body. No browser binary in your SvelteKit deployment.
Why receipts become PDFs
A receipt is proof a payment happened, and customers attach it to expense claims. It has to survive being forwarded, printed and filed by someone who never had an account with you. That is the difference between a document and a view of a database, and it is why ecommerce and point-of-sale teams keep asking for this.
What a receipt has to carry
Before any of the code below matters, the template has to produce a document that is actually a receipt. These are the fields that make it one, and the ones a reader or an auditor will look for first.
- the payment reference from the processor, which is what a dispute is traced by
- the amount actually captured, which is not always the amount ordered
- the payment method, usually the card brand and last four digits
- the timestamp with a timezone, since expense systems reconcile by date
- the merchant legal name, which may differ from the brand on the site
Turning your Svelte components, rendered server side template into a document
You already have the markup. Const { html, head } = Invoice.render(data) gives you it as a string, which is the only input the render needs. Which adapter you build with decides whether a browser binary can exist at all. adapter-node can host one; adapter-vercel, adapter-cloudflare and adapter-netlify cannot. Choosing an HTTP render keeps the adapter choice open.
The SvelteKit implementation
fetch ships with the runtime, so this adds no dependency. The render happens in a +server.ts endpoint returning a Response, and you return a Response built from the upstream body.
// src/routes/receipts/[id]/pdf/+server.ts
import { error } from "@sveltejs/kit";
import { PDFPIPE_KEY } from "$env/static/private";
import ReceiptDocument from "$lib/documents/ReceiptDocument.svelte";
import { render } from "svelte/server";
export async function GET({ params, fetch }) {
const receipt = await getReceipt(params.id);
// head carries the scoped styles. Without it the document renders with
// browser defaults, because the CSS file it would link is not reachable.
const { head, body } = render(ReceiptDocument, { props: { receipt } });
const html = `<!doctype html><html><head>${head}</head><body>${body}</body></html>`;
const upstream = await fetch("https://api.pdfpipe.xyz/v1/pdf", {
method: "POST",
headers: {
Authorization: `Bearer ${PDFPIPE_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
html,
options: { format: "A4", printBackground: true },
}),
});
if (!upstream.ok) error(502, "render failed");
return new Response(upstream.body, {
headers: {
"Content-Type": "application/pdf",
"Content-Disposition": `attachment; filename="receipt-${params.id}.pdf"`,
},
});
}The CSS that makes a receipt page correctly
The layout problem specific to this document is that receipts are short and usually want a narrow page, so the default A4 canvas leaves an expanse of white unless the page size is set deliberately. These rules handle it.
/* A receipt on A4 is mostly white space. Set the page to the
content, and let it grow only as far as the items require. */
@page {
size: 80mm 200mm;
margin: 6mm;
}
body { font-size: 11px; }What goes wrong in SvelteKit
A component's render() output does not include its scoped styles unless you also emit the head string, and even then the styles reference a CSS file the renderer cannot fetch. Inline them into the markup you send.
What people try first
Most SvelteKit projects reach for puppeteer in a +server.ts route, which works locally with adapter-node and then fails on the first deploy to any edge target. That works until it is running on more than one machine, at which point the browser becomes the thing you operate rather than the thing you use.
Where the receipt lives afterwards
Rendering is the short part. The customer keeps it, not you, and they submit it to an expense system months later. It has to be readable by software that never saw your site, which is why the amount and reference belong in selectable text rather than inside an image.
Getting the document right
- Check the amount paid and the payment reference, which is what an expense system matches against.
- Generation is triggered by a successful payment webhook, so size the timeout for that path rather than for a health check.
- Volume arrives in bursts, so queue the render rather than doing it inside the request that triggered it.
- Backgrounds are painted by default here, so a design that uses colour needs nothing set. Only an explicit print_background of false turns them off.
Frequently asked
Do I need Chromium installed to generate receipts from SvelteKit?
No. The render happens over HTTP, so your SvelteKit deployment stays the size it is now. That is the main reason to use an API rather than puppeteer in a +server.ts route, which works locally with adapter-node and then fails on the first deploy to any edge target.
How do I stop a long receipt using all the memory?
Return a Response built from the upstream body. A component's render() output does not include its scoped styles unless you also emit the head string, and even then the styles reference a CSS file the renderer cannot fetch. Inline them into the markup you send.
What has to be on a receipt?
At minimum: the payment reference from the processor, which is what a dispute is traced by; the amount actually captured, which is not always the amount ordered; the payment method, usually the card brand and last four digits. The one to get right before anything else is the amount paid and the payment reference, which is what an expense system matches against.
Do I need to store the generated receipts?
Depends on the document, and this one has a clear answer: the customer keeps it, not you, and they submit it to an expense system months later. It has to be readable by software that never saw your site, which is why the amount and reference belong in selectable text rather than inside an image.
Can I keep my existing receipt template?
Yes, if it produces HTML. Whatever renders your receipt view today can render the same markup for the PDF, which is why the CSS above is the only new thing you write.
Related
Other SvelteKit documents, and the same receipt in other stacks.
Invoice PDFs in SvelteKit
an invoice is a legal record of a demand for payment
Report PDFs in SvelteKit
a report is a snapshot of numbers at a moment in time. Its whole value is that it does not change when the underlying dashboard does.
Certificate PDFs in SvelteKit
a certificate is meant to be shown to a third party who has no relationship with the issuing system
Receipt PDFs in Node.js
Using fetch, in a route handler that returns the response body directly.
Receipt PDFs in Python
Using httpx, in an async endpoint that returns a streaming response.
Receipt PDFs in PHP
Using cURL, in a controller action that echoes the body with a PDF Content-Type.
The same thing in plain Node.js
Without the framework, using fetch directly.
When the output is wrong
Blank pages, missing backgrounds, breaks in the wrong place, by symptom.
All stacks and documents
The full grid of what this covers.
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