replaced current and previous properties with symbols

Avoid serializing them and encountering issues circular references

src/create/schema/index.ts

@@ -13,6 +13,7 @@ import { enhanceWithMetadata } from './metadata';
 import { createSchemaSwitch } from './parsers';
 import { verifyEffects } from './parsers/transform';
 import type { CreateSchemaOptions } from './single';
+import { currentSymbol, previousSymbol } from '../../extendZodTypes';
 
 export type LazyMap = Map<ZodType, true>;
 
@@ -220,16 +221,16 @@ export const createSchemaOrRef = <
     return existingRef;
   }
 
-  const previous = zodSchema._def.zodOpenApi?.previous
-    ? (createSchemaOrRef(zodSchema._def.zodOpenApi.previous, state, true) as
+  const previous = zodSchema._def.zodOpenApi?.[previousSymbol]
+    ? (createSchemaOrRef(zodSchema._def.zodOpenApi[previousSymbol], state, true) as
         | RefObject
         | undefined)
     : undefined;
 
   const current =
-    zodSchema._def.zodOpenApi?.current &&
-    zodSchema._def.zodOpenApi.current !== zodSchema
-      ? (createSchemaOrRef(zodSchema._def.zodOpenApi.current, state, true) as
+    zodSchema._def.zodOpenApi?.[currentSymbol] &&
+    zodSchema._def.zodOpenApi[currentSymbol] !== zodSchema
+      ? (createSchemaOrRef(zodSchema._def.zodOpenApi[currentSymbol], state, true) as
           | RefObject
           | undefined)
       : undefined;

src/create/schema/metadata.test.ts

@@ -253,10 +253,10 @@ describe('enhanceWithMetadata', () => {
               "coerce": false,
               "typeName": "ZodString",
               "zodOpenApi": {
-                "current": [Circular],
                 "openapi": {
                   "ref": "foo",
                 },
+                Symbol(current): [Circular],
               },
             },
             "and": [Function],
@@ -339,10 +339,10 @@ describe('enhanceWithMetadata', () => {
               "coerce": false,
               "typeName": "ZodString",
               "zodOpenApi": {
-                "current": [Circular],
                 "openapi": {
                   "ref": "foo",
                 },
+                Symbol(current): [Circular],
               },
             },
             "and": [Function],
@@ -604,10 +604,10 @@ describe('enhanceWithMetadata', () => {
               "coerce": false,
               "typeName": "ZodString",
               "zodOpenApi": {
-                "current": [Circular],
                 "openapi": {
                   "ref": "foo",
                 },
+                Symbol(current): [Circular],
               },
             },
             "and": [Function],
@@ -690,10 +690,10 @@ describe('enhanceWithMetadata', () => {
               "coerce": false,
               "typeName": "ZodString",
               "zodOpenApi": {
-                "current": [Circular],
                 "openapi": {
                   "ref": "foo",
                 },
+                Symbol(current): [Circular],
               },
             },
             "and": [Function],
@@ -934,4 +934,9 @@ describe('enhanceWithMetadata', () => {
 ]
 `);
   });
+
+  it('does not fail JSON serialization', () => {
+    const FooSchema = z.string().openapi({ ref: 'foo' });
+    expect(()=>{JSON.stringify(FooSchema)}).not.toThrow();
+  });
 });

src/extendZod.test.ts

@@ -2,6 +2,7 @@ import { z } from 'zod';
 
 import { createSchema } from './create/schema/single';
 import { extendZodWithOpenApi } from './extendZod';
+import { currentSymbol, previousSymbol } from './extendZodTypes';
 
 extendZodWithOpenApi(z);
 
@@ -22,16 +23,16 @@ describe('extendZodWithOpenApi', () => {
     expect(a._def.zodOpenApi?.openapi?.description).toBe('test');
     expect(b._def.zodOpenApi?.openapi?.description).toBe('test2');
     expect(
-      b._def.zodOpenApi?.previous?._def.zodOpenApi?.openapi?.description,
+      b._def.zodOpenApi?.[previousSymbol]?._def.zodOpenApi?.openapi?.description,
     ).toBe('test');
   });
 
   it('sets current metadata when a schema is used again', () => {
     const a = z.string().openapi({ ref: 'a' });
     const b = a.uuid();
 
-    expect(a._def.zodOpenApi?.current).toBe(a);
-    expect(b._def.zodOpenApi?.current).toBe(a);
+    expect(a._def.zodOpenApi?.[currentSymbol]).toBe(a);
+    expect(b._def.zodOpenApi?.[currentSymbol]).toBe(a);
   });
 
   it('adds ._def.zodOpenApi.openapi fields to a zod type', () => {
@@ -53,7 +54,7 @@ describe('extendZodWithOpenApi', () => {
     const b = a.extend({ b: z.string() });
 
     expect(a._def.zodOpenApi?.openapi?.ref).toBe('a');
-    expect(b._def.zodOpenApi?.previous).toStrictEqual(a);
+    expect(b._def.zodOpenApi?.[previousSymbol]).toStrictEqual(a);
   });
 
   it('removes previous openapi ref for an object when .omit or .pick is used', () => {
@@ -74,7 +75,7 @@ describe('extendZodWithOpenApi', () => {
     });
 
     expect(a._def.zodOpenApi?.openapi?.ref).toBe('a');
-    expect(b._def.zodOpenApi?.previous).toStrictEqual(a);
+    expect(b._def.zodOpenApi?.[previousSymbol]).toStrictEqual(a);
     expect(c._def.zodOpenApi?.openapi).toEqual({});
     expect(d._def.zodOpenApi?.openapi).toEqual({});
 

src/extendZod.ts

@@ -1,6 +1,7 @@
 import type { ZodRawShape, ZodTypeDef, z } from 'zod';
 
 import './extendZodTypes';
+import { currentSymbol, previousSymbol } from './extendZodTypes';
 
 type ZodOpenApiMetadataDef = NonNullable<ZodTypeDef['zodOpenApi']>;
 type ZodOpenApiMetadata = ZodOpenApiMetadataDef['openapi'];
@@ -42,11 +43,11 @@ export function extendZodWithOpenApi(zod: typeof z) {
     });
 
     // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access
-    result._def.zodOpenApi.current = result;
+    result._def.zodOpenApi[currentSymbol] = result;
 
     if (zodOpenApi) {
       // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
-      result._def.zodOpenApi.previous = this;
+      result._def.zodOpenApi[previousSymbol] = this;
     }
 
     // eslint-disable-next-line @typescript-eslint/no-unsafe-return
@@ -63,13 +64,13 @@ export function extendZodWithOpenApi(zod: typeof z) {
     if (def.zodOpenApi) {
       const cloned = { ...def.zodOpenApi };
       cloned.openapi = mergeOpenApi({ description: args[0] }, cloned.openapi);
-      cloned.previous = this;
-      cloned.current = result;
+      cloned[previousSymbol] = this;
+      cloned[currentSymbol] = result;
       def.zodOpenApi = cloned;
     } else {
       def.zodOpenApi = {
         openapi: { description: args[0] },
-        current: result,
+        [currentSymbol]: result,
       };
     }
 
@@ -88,11 +89,11 @@ export function extendZodWithOpenApi(zod: typeof z) {
     if (zodOpenApi) {
       const cloned = { ...zodOpenApi };
       cloned.openapi = mergeOpenApi({}, cloned.openapi);
-      cloned.previous = this;
+      cloned[previousSymbol] = this;
       extendResult._def.zodOpenApi = cloned;
     } else {
       extendResult._def.zodOpenApi = {
-        previous: this,
+        [previousSymbol]: this,
       };
     }
 
@@ -112,8 +113,8 @@ export function extendZodWithOpenApi(zod: typeof z) {
     if (zodOpenApi) {
       const cloned = { ...zodOpenApi };
       cloned.openapi = mergeOpenApi({}, cloned.openapi);
-      delete cloned.previous;
-      delete cloned.current;
+      delete cloned[previousSymbol];
+      delete cloned[currentSymbol];
       omitResult._def.zodOpenApi = cloned;
     }
 
@@ -133,8 +134,8 @@ export function extendZodWithOpenApi(zod: typeof z) {
     if (zodOpenApi) {
       const cloned = { ...zodOpenApi };
       cloned.openapi = mergeOpenApi({}, cloned.openapi);
-      delete cloned.previous;
-      delete cloned.current;
+      delete cloned[previousSymbol];
+      delete cloned[currentSymbol];
       pickResult._def.zodOpenApi = cloned;
     }
     // eslint-disable-next-line @typescript-eslint/no-unsafe-return, @typescript-eslint/no-explicit-any

src/extendZodTypes.ts

@@ -7,6 +7,9 @@ type SchemaObject = oas30.SchemaObject & oas31.SchemaObject;
 
 type ReplaceDate<T> = T extends Date ? Date | string : T;
 
+export const currentSymbol = Symbol("current");
+export const previousSymbol = Symbol("previous");
+
 /**
  * zod-openapi metadata
  */
@@ -77,12 +80,12 @@ interface ZodOpenApiMetadataDef {
   /**
    * Used to keep track of the Zod Schema had `.openapi` called on it
    */
-  current?: ZodTypeAny;
+  [currentSymbol]?: ZodTypeAny;
   /**
    * Used to keep track of the previous Zod Schema that had `.openapi` called on it if another `.openapi` is called.
    * This can also be present when .extend is called on an object.
    */
-  previous?: ZodTypeAny;
+  [previousSymbol]?: ZodTypeAny;
 }
 
 interface ZodOpenApiExtendMetadata {