fix(conform-zod): type coercion for branded types (#864)

Co-authored-by: KRAUSIL <[email protected]>
Co-authored-by: Edmund Hung <[email protected]>

Author: 3 people

.changeset/early-buckets-complain.md

@@ -0,0 +1,5 @@
+---
+'@conform-to/zod': patch
+---
+
+fix: type coercion with [branded](https://zod.dev/?id=brand) types (e.g. `z.string().brand()`)

packages/conform-zod/coercion.ts

@@ -13,6 +13,7 @@ import {
 	lazy,
 	any,
 	ZodCatch,
+	ZodBranded,
 } from 'zod';
 import type {
 	ZodDiscriminatedUnionOption,
@@ -287,6 +288,11 @@ export function enableTypeCoercion<Schema extends ZodTypeAny>(
 				]),
 			),
 		});
+	} else if (def.typeName === 'ZodBranded') {
+		schema = new ZodBranded({
+			...def,
+			type: enableTypeCoercion(def.type, cache),
+		});
 	} else if (def.typeName === 'ZodTuple') {
 		schema = new ZodTuple({
 			...def,

tests/conform-zod.spec.ts

@@ -1253,6 +1253,89 @@ describe('conform-zod', () => {
 				reply: expect.any(Function),
 			});
 		});
+
+		test('z.brand', () => {
+			const schema = z
+				.object({
+					a: z.string().brand(),
+					b: z.number().brand(),
+					c: z.boolean().brand(),
+					d: z.date().brand(),
+					e: z.instanceof(File).brand(),
+					f: z.string().optional().brand(),
+					g: z.string().brand().optional(),
+				})
+				.brand();
+			expect(
+				parseWithZod(
+					createFormData([
+						['a', ''],
+						['b', ''],
+						['c', ''],
+						['d', ''],
+						['e', ''],
+						['f', ''],
+						['g', ''],
+					]),
+					{ schema },
+				),
+			).toEqual({
+				status: 'error',
+				payload: {
+					a: '',
+					b: '',
+					c: '',
+					d: '',
+					e: '',
+					f: '',
+					g: '',
+				},
+				error: {
+					a: ['Required'],
+					b: ['Required'],
+					c: ['Required'],
+					d: ['Required'],
+					e: ['Input not instance of File'],
+				},
+				reply: expect.any(Function),
+			});
+			const coercionTypesSchema = z.object({
+				a: z.string().brand(),
+				b: z.number().brand(),
+				c: z.boolean().brand(),
+				d: z.date().brand(),
+				e: z.bigint().brand(),
+			});
+			expect(
+				parseWithZod(
+					createFormData([
+						['a', 'hello world'],
+						['b', '42'],
+						['c', 'on'],
+						['d', '1970-01-01'],
+						['e', '0x1fffffffffffff'],
+					]),
+					{ schema: coercionTypesSchema },
+				),
+			).toEqual({
+				status: 'success',
+				payload: {
+					a: 'hello world',
+					b: '42',
+					c: 'on',
+					d: '1970-01-01',
+					e: '0x1fffffffffffff',
+				},
+				value: {
+					a: 'hello world',
+					b: 42,
+					c: true,
+					d: new Date('1970-01-01'),
+					e: BigInt('0x1fffffffffffff'),
+				},
+				reply: expect.any(Function),
+			});
+		});
 	});
 
 	test('parseWithZod with errorMap', () => {