fix: OpenAPI generator: fix nullable param parsing (#145)

* Fix nullable params parsing

* Test the fix

* Fix tests

apps/example-todo-app/pages/api/todo/add.ts

@@ -20,6 +20,7 @@ export const jsonBody = z.object({
     ---
     This is an unused, deprecated field.
   `),
+  description: z.string().nullable().optional(),
 })
 
 export const route_spec = checkRouteSpec({

apps/example-todo-app/tests/openapi-generation/openapi-generation.test.ts

@@ -9,3 +9,20 @@ test("should generate openapi with expected properties", async (t) => {
   )
   t.deepEqual(typeof openapiJson, "object")
 })
+
+test("nullable param is correctly parsed", async (t) => {
+  const openapiJson = JSON.parse(
+    await generateOpenAPI({
+      packageDir: ".",
+    })
+  )
+
+  const routeSpec = openapiJson.paths["/api/todo/add"].post
+  const descriptionParam =
+    routeSpec.requestBody.content["application/json"].schema.properties
+      .description
+
+  t.truthy(descriptionParam)
+  t.is(descriptionParam.type, "string")
+  t.true(descriptionParam.nullable)
+})

packages/nextlove/src/generators/lib/zod-openapi.ts

@@ -368,7 +368,7 @@ function parseNullable({
 }: ParsingArgs<z.ZodNullable<OpenApiZodAny>>): SchemaObject {
   const schema = generateSchema(zodRef.unwrap(), useOutput)
   return merge(
-    { ...schema, type: [schema.type, "null"] as SchemaObjectType[] },
+    { ...schema, type: schema.type, nullable: true },
     parseDescription(zodRef),
     ...schemas
   )