Standard Schema validation

No package in this collection ships a validation library, and none of them requires a particular one. Where a package needs to validate something — a document's frontmatter, a webhook's payload, a job's arguments — it accepts any schema implementing Standard Schema, and infers the result type from the schema you handed it.

What that looks like

import { Markdown } from "@sdxc/markdown";
import * as s from "remix/data-schema";

let Frontmatter = s.object({ title: s.string(), draft: s.optional(s.boolean()) });

let parsed = Markdown.parse(source, { frontmatter: Frontmatter });
// parsed.data.frontmatter is { title: string; draft?: boolean }

remix/data-schema is the schema library used throughout this collection's own code, but it is not special to the packages: Valibot, ArkType and anything else implementing the interface work in exactly the same call.

Validating on your own

@sdxc/validate is the general case: it takes a schema and a plain object, a FormData, a URLSearchParams or a whole Request, and answers with a Result instead of throwing.

import { isFailure } from "@sdxc/result";
import { validate } from "@sdxc/validate";

async function handler(request: Request) {
	let result = await validate(request, schema);
	if (isFailure(result)) return Response.json({ errors: result.error.issues }, { status: 400 });

	return Response.json({ id: await create(result.data) });
}

A Request is read according to its Content-Type, so one call covers JSON, a urlencoded form and a multipart submission. A FormData flattens first: a name submitted once becomes a value, a name submitted more than once becomes an array.

Why it is an interface rather than a dependency

A validation library is a choice an application makes once and lives with. A package that picked one for you would either force its choice into your bundle or force you to convert between two schema languages at the boundary. Accepting the interface means the package never enters that argument: it asks for something that can validate, and whatever you already use answers.

The cost is that the failure shape is the interface's. A validation failure carries issues — the Standard Schema issue list — rather than a shape any one library invented.