Add .toJSONSchema() method (#5477)

* Checkpoint

* Checkpoint

* Implement toJSONSchema method

* Implement Standard JSON Schema

* Clean up

* Add back files

* Revert "Add back files"

This reverts commit 3e8ba43.

* Fix resolution bug

* Tweak

* Test

* Refactor files

* Address reviews

* Address pullfrog reviews

Author: colinhacks

packages/docs/content/json-schema.mdx

@@ -215,10 +215,18 @@ Below is a quick reference for each supported parameter. Each one is explained i
 interface ToJSONSchemaParams {
   /** The JSON Schema version to target.
    * - `"draft-2020-12"` — Default. JSON Schema Draft 2020-12
-   * - `"draft-7"` — JSON Schema Draft 7
-   * - `"draft-4"` — JSON Schema Draft 4
+   * - `"draft-07"` — JSON Schema Draft 7
+   * - `"draft-04"` — JSON Schema Draft 4
    * - `"openapi-3.0"` — OpenAPI 3.0 Schema Object */
-  target?: "draft-4" | "draft-7" | "draft-2020-12" | "openapi-3.0";
+  target?:
+    | "draft-04"
+    | "draft-4"
+    | "draft-07"
+    | "draft-7"
+    | "draft-2020-12"
+    | "openapi-3.0"
+    | ({} & string)
+    | undefined;
 
   /** A registry used to look up metadata for each schema. 
    * Any schema with an `id` property will be extracted as a $def. */
@@ -251,9 +259,9 @@ interface ToJSONSchemaParams {
 To set the target JSON Schema version, use the `target` parameter. By default, Zod will target Draft 2020-12.   
 
 ```ts
-z.toJSONSchema(schema, { target: "draft-7" });
+z.toJSONSchema(schema, { target: "draft-07" });
 z.toJSONSchema(schema, { target: "draft-2020-12" });
-z.toJSONSchema(schema, { target: "draft-4" });
+z.toJSONSchema(schema, { target: "draft-04" });
 z.toJSONSchema(schema, { target: "openapi-3.0" });
 ```
 

packages/zod/src/v4/classic/schemas.ts

@@ -1,7 +1,8 @@
-import { test } from "vitest";
-// import * as z from "zod/v4";
+import { expect, test } from "vitest";
 
-test(() => {});
+test(() => {
+  expect(2).toBe(2);
+});
 // test("overload types", () => {
 //   const schema = z.string().json();
 //   util.assertEqual<typeof schema, z.ZodString>(true);

packages/zod/src/v4/classic/tests/json.test.ts

@@ -55,3 +55,80 @@ test("length checks", async () => {
     }
   `);
 });
+
+test("schemas conform to StandardJSONSchemaV1", async () => {
+  const schema = z.codec(z.string(), z.number(), {
+    decode: (str) => Number.parseFloat(str),
+    encode: (num) => num.toString(),
+  });
+  expect(schema["~standard"].validate).toBeTypeOf("function");
+  expect(await schema["~standard"].validate("42")).toMatchInlineSnapshot(`
+		{
+		  "value": 42,
+		}
+	`);
+  expect(schema["~standard"].jsonSchema.input({ target: "draft-2020-12" })).toMatchInlineSnapshot(`
+		{
+		  "$schema": "https://json-schema.org/draft/2020-12/schema",
+		  "type": "string",
+		}
+	`);
+  expect(schema["~standard"].jsonSchema.output({ target: "draft-2020-12" })).toMatchInlineSnapshot(`
+		{
+		  "$schema": "https://json-schema.org/draft/2020-12/schema",
+		  "type": "number",
+		}
+	`);
+});
+
+test(".toJSONSchema() returns StandardJSONSchemaV1", async () => {
+  const codec = z.codec(z.string(), z.number(), {
+    decode: (str) => Number.parseFloat(str),
+    encode: (num) => num.toString(),
+  });
+  const result = codec.toJSONSchema();
+  expect(result["~standard"].validate).toBeTypeOf("function");
+  expect(await result["~standard"].validate("42")).toMatchInlineSnapshot(`
+		{
+		  "value": 42,
+		}
+	`);
+  expect(result["~standard"].jsonSchema.input({ target: "draft-2020-12" })).toMatchInlineSnapshot(`
+		{
+		  "$schema": "https://json-schema.org/draft/2020-12/schema",
+		  "type": "string",
+		}
+	`);
+  expect(result["~standard"].jsonSchema.output({ target: "draft-2020-12" })).toMatchInlineSnapshot(`
+		{
+		  "$schema": "https://json-schema.org/draft/2020-12/schema",
+		  "type": "number",
+		}
+	`);
+});
+
+test("z.toJSONSchema() returns StandardJSONSchemaV1", async () => {
+  const codec = z.codec(z.string(), z.number(), {
+    decode: (str) => Number.parseFloat(str),
+    encode: (num) => num.toString(),
+  });
+  const result = z.toJSONSchema(codec);
+  expect(result["~standard"].validate).toBeTypeOf("function");
+  expect(await result["~standard"].validate("42")).toMatchInlineSnapshot(`
+		{
+		  "value": 42,
+		}
+	`);
+  expect(result["~standard"].jsonSchema.input({ target: "draft-2020-12" })).toMatchInlineSnapshot(`
+		{
+		  "$schema": "https://json-schema.org/draft/2020-12/schema",
+		  "type": "string",
+		}
+	`);
+  expect(result["~standard"].jsonSchema.output({ target: "draft-2020-12" })).toMatchInlineSnapshot(`
+		{
+		  "$schema": "https://json-schema.org/draft/2020-12/schema",
+		  "type": "number",
+		}
+	`);
+});