fix(conform-zod): enable zod object coercion (#733)

.changeset/tender-kiwis-flash.md

@@ -0,0 +1,7 @@
+---
+'@conform-to/zod': patch
+---
+
+fix(conform-zod): enable zod object coercion
+
+Conform should support nested fields with only checkboxes now. Fix #391.

packages/conform-zod/coercion.ts

@@ -185,17 +185,28 @@ export function enableTypeCoercion<Schema extends ZodTypeAny>(
 				}),
 			);
 	} else if (def.typeName === 'ZodObject') {
-		const shape = Object.fromEntries(
-			Object.entries(def.shape()).map(([key, def]) => [
-				key,
-				// @ts-expect-error see message above
-				enableTypeCoercion(def, cache),
-			]),
-		);
-		schema = new ZodObject({
-			...def,
-			shape: () => shape,
-		});
+		schema = any()
+			.transform((value) => {
+				if (typeof value === 'undefined') {
+					// Defaults it to an empty object
+					return {};
+				}
+
+				return value;
+			})
+			.pipe(
+				new ZodObject({
+					...def,
+					shape: () =>
+						Object.fromEntries(
+							Object.entries(def.shape()).map(([key, def]) => [
+								key,
+								// @ts-expect-error see message above
+								enableTypeCoercion(def, cache),
+							]),
+						),
+				}),
+			);
 	} else if (def.typeName === 'ZodEffects') {
 		if (isFileSchema(type as unknown as ZodEffects<any, any, any>)) {
 			schema = any()

tests/conform-zod.spec.ts

@@ -524,6 +524,56 @@ describe('conform-zod', () => {
 			});
 		});
 
+		test('z.object', () => {
+			const schema = z.object({
+				a: z.object({
+					text: z.string({
+						required_error: 'required',
+					}),
+					flag: z.boolean({
+						required_error: 'required',
+					}),
+				}),
+				b: z
+					.object({
+						text: z.string({
+							required_error: 'required',
+						}),
+						flag: z.boolean({
+							required_error: 'required',
+						}),
+					})
+					.optional(),
+			});
+
+			expect(parseWithZod(createFormData([]), { schema })).toEqual({
+				status: 'error',
+				payload: {},
+				error: {
+					'a.text': ['required'],
+					'a.flag': ['required'],
+				},
+				reply: expect.any(Function),
+			});
+			expect(
+				parseWithZod(createFormData([['b.text', '']]), { schema }),
+			).toEqual({
+				status: 'error',
+				payload: {
+					b: {
+						text: '',
+					},
+				},
+				error: {
+					'a.text': ['required'],
+					'a.flag': ['required'],
+					'b.text': ['required'],
+					'b.flag': ['required'],
+				},
+				reply: expect.any(Function),
+			});
+		});
+
 		test('z.array', () => {
 			const createSchema = (
 				element: z.ZodTypeAny = z.string({