Merge branch 'master' of github.com:samchungy/zod-openapi

Author: samchungy

.changeset/moody-books-cover.md

@@ -0,0 +1,37 @@
+---
+'zod-openapi': minor
+---
+
+Change `ZodUndefined` behaviour
+
+This restores how `z.undefined()` is rendered to pre Zod v3.25.75.
+
+It is now rendered as:
+
+```json
+{
+  "not": {}
+}
+```
+
+If you want to override this behaviour you can customise this with the `override` function passed into the `createDocument` function.
+
+eg.
+
+```ts
+import { createDocument } from 'zod-openapi';
+
+createDocument(
+  z.object({
+    name: z.undefined().optional(),
+  }),
+  {
+    override: (ctx) => {
+      if (ctx.zodSchema._zod.def.type === 'undefined') {
+        // This will change the behaviour back to throwing an error
+        delete ctx.jsonSchema.not;
+      }
+    },
+  },
+);
+```

package.json

@@ -65,7 +65,7 @@
     "skuba": "11.1.0",
     "tsdown": "0.12.9",
     "yaml": "2.8.0",
-    "zod": "4.0.1"
+    "zod": "4.0.5"
   },
   "peerDependencies": {
     "zod": "^3.25.74 || ^4.0.0"

pnpm-lock.yaml

@@ -84,6 +84,10 @@ export const override: Override = (ctx) => {
       }
       break;
     }
+    case 'undefined': {
+      ctx.jsonSchema.not = {};
+      break;
+    }
   }
 };
 

src/create/schema/override.ts

@@ -220,6 +220,7 @@ describe('required', () => {
       const ref = z.string().meta({ id: 'ref' });
       const oref = z.string().optional().meta({ id: 'oref' });
       const schema = z.object({
+        a: z.undefined(),
         b: z.never().optional(),
         d: z.string().optional(),
         e: z.string().nullish(),
@@ -242,6 +243,7 @@ describe('required', () => {
         schema: {
           type: 'object',
           properties: {
+            a: { not: {} },
             b: { not: {} },
             d: { type: 'string' },
             e: { anyOf: [{ type: 'string' }, { type: 'null' }] },
@@ -275,6 +277,7 @@ describe('required', () => {
         d: z.literal(null),
         e: z.union([z.string(), z.number()]),
         f: z.custom((r) => r !== undefined),
+        g: z.undefined(),
       });
 
       const ctx = createInputContext();
@@ -293,6 +296,7 @@ describe('required', () => {
             d: { type: 'null', const: null },
             e: { anyOf: [{ type: 'string' }, { type: 'number' }] },
             f: {},
+            g: { not: {} },
           },
           required: ['a', 'b', 'c', 'd', 'e', 'f'],
         },

src/create/schema/tests/object.test.ts

@@ -0,0 +1,18 @@
+import * as z from 'zod/v4';
+
+import { type SchemaResult, createSchema } from '../schema';
+
+describe('undefined', () => {
+  it('should create an empty schema for undefined', () => {
+    const schema = z.undefined();
+
+    const result = createSchema(schema);
+
+    expect(result).toEqual<SchemaResult>({
+      schema: {
+        not: {},
+      },
+      components: {},
+    });
+  });
+});