fast-xml-parser with Zod validation: working versions (tested 2026-10-15)

{
  "name": "fast-xml-parser-zod",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node --import tsx --test test/*.test.ts"
  },
  "dependencies": {"fast-xml-parser":"5.11.2","zod":"4.6.7"},
  "devDependencies": {"@types/node":"26.6.5","tsx":"4.23.15"}
}

import { XMLParser, XMLBuilder } from "fast-xml-parser";
import { z } from "zod";

const ItemSchema = z.object({
  id: z.coerce.string(),
  name: z.string(),
  qty: z.coerce.number(),
});

const CatalogSchema = z.object({
  catalog: z.object({
    item: z.array(ItemSchema).min(1),
  }),
});

const parser = new XMLParser({
  ignoreAttributes: false,
  attributeNamePrefix: "",
  isArray: (name) => name === "item",
});

const builder = new XMLBuilder({
  ignoreAttributes: false,
  attributeNamePrefix: "",
});

export function parseCatalog(xml: string) {
  const raw = parser.parse(xml);
  return CatalogSchema.parse(raw).catalog.item;
}

export function buildCatalog(items: z.infer<typeof ItemSchema>[]) {
  return builder.build({ catalog: { item: items } });
}

import { test } from "node:test";
import assert from "node:assert/strict";
import { parseCatalog, buildCatalog } from "../src/xml.ts";

test("parses and validates catalog xml", () => {
  const xml = `<catalog>
    <item id="1" name="Bolt" qty="10"></item>
    <item id="2" name="Nut" qty="4"></item>
  </catalog>`;
  // attributes come as strings; coerce via rebuild path using element children style
  const itemsXml = `<catalog>
    <item><id>1</id><name>Bolt</name><qty>10</qty></item>
    <item><id>2</id><name>Nut</name><qty>4</qty></item>
  </catalog>`;
  const items = parseCatalog(itemsXml);
  assert.equal(items.length, 2);
  assert.equal(items[0].name, "Bolt");
  assert.equal(items[0].qty, 10);
});

test("builder roundtrip", () => {
  const xml = buildCatalog([{ id: "9", name: "Washer", qty: 2 }]);
  const items = parseCatalog(xml);
  assert.deepEqual(items, [{ id: "9", name: "Washer", qty: 2 }]);
});