From b49a5a74f4e3a65b14905427c8b86be8b129a8e3 Mon Sep 17 00:00:00 2001
From: Sam Chung <samchungy@gmail.com>
Date: Sun, 15 Dec 2024 00:03:45 +1100
Subject: [PATCH] Update example types (#374)

---
 src/extendZod.test.ts | 25 +++++++++++++++++++++++++
 src/extendZodTypes.ts |  8 +++++---
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/src/extendZod.test.ts b/src/extendZod.test.ts
index faea140..0f35a13 100644
--- a/src/extendZod.test.ts
+++ b/src/extendZod.test.ts
@@ -89,4 +89,29 @@ describe('extendZodWithOpenApi', () => {
 
     expect(barString._def.zodOpenApi?.openapi?.effectType).toBe('input');
   });
+
+  it('makes a date example accept strings', () => {
+    const fooString = z.union([z.date().optional(), z.string(), z.null()]);
+
+    const barString = fooString.openapi({
+      examples: [null, '2021-01-01'],
+    });
+
+    expect(barString._def.zodOpenApi?.openapi?.examples).toEqual([
+      null,
+      '2021-01-01',
+    ]);
+  });
+
+  it('makes allows example to accept undefined but forbids undefined in examples', () => {
+    const fooString = z.union([z.date().optional(), z.string(), z.null()]);
+
+    const barString = fooString.openapi({
+      example: undefined,
+      // @ts-expect-error - Testing types
+      examples: [undefined],
+    });
+
+    expect(barString._def.zodOpenApi?.openapi?.example).toBeUndefined();
+  });
 });
diff --git a/src/extendZodTypes.ts b/src/extendZodTypes.ts
index af6e16b..c1762fc 100644
--- a/src/extendZodTypes.ts
+++ b/src/extendZodTypes.ts
@@ -1,20 +1,22 @@
-import type { ZodDate, ZodObject, ZodTypeAny, z } from 'zod';
+import type { ZodObject, ZodTypeAny, z } from 'zod';
 
 import type { CreationType } from './create/components';
 import type { oas30, oas31 } from './openapi3-ts/dist';
 
 type SchemaObject = oas30.SchemaObject & oas31.SchemaObject;
 
+type ReplaceDate<T> = T extends Date ? Date | string : T;
+
 /**
  * zod-openapi metadata
  */
 interface ZodOpenApiMetadata<
   T extends ZodTypeAny,
-  TInferred = z.input<T> | z.output<T>,
+  TInferred = Exclude<ReplaceDate<z.input<T> | z.output<T>>, undefined>,
 > extends SchemaObject {
   example?: TInferred;
   examples?: [TInferred, ...TInferred[]];
-  default?: T extends ZodDate ? string : TInferred;
+  default?: TInferred;
   /**
    * Used to set the output of a ZodUnion to be `oneOf` instead of `allOf`
    */