From 9818905f7a7724485cdeea8d040a70d8bdd34220 Mon Sep 17 00:00:00 2001
From: Kui-kui <cedrickui@gmail.com>
Date: Wed, 12 Nov 2025 17:16:14 +0100
Subject: [PATCH] fix(enum): handle nullable enum when useEnums=true

---
 .../src/core/schemaToTypeAliasDeclaration.ts  |  5 ++++-
 plugins/typescript/src/fixtures/petstore.ts   | 14 ++++++++++--
 .../generators/generateSchemaTypes.test.ts    | 22 +++++++++++++++++--
 3 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/plugins/typescript/src/core/schemaToTypeAliasDeclaration.ts b/plugins/typescript/src/core/schemaToTypeAliasDeclaration.ts
index 1d9b4a10..e59a21c5 100644
--- a/plugins/typescript/src/core/schemaToTypeAliasDeclaration.ts
+++ b/plugins/typescript/src/core/schemaToTypeAliasDeclaration.ts
@@ -173,7 +173,10 @@ export const getType = (
 
   if (schema.enum) {
     if (isNodeEnum) {
-      return f.createTypeReferenceNode(f.createIdentifier(pascal(name || "")));
+      return f.createUnionTypeNode([
+        f.createTypeReferenceNode(f.createIdentifier(pascal(name || ""))),
+        ...(schema.nullable ? [f.createLiteralTypeNode(f.createNull())] : []),
+      ]);
     }
 
     const unionTypes = f.createUnionTypeNode([
diff --git a/plugins/typescript/src/fixtures/petstore.ts b/plugins/typescript/src/fixtures/petstore.ts
index dee08367..c9f9af14 100644
--- a/plugins/typescript/src/fixtures/petstore.ts
+++ b/plugins/typescript/src/fixtures/petstore.ts
@@ -364,8 +364,13 @@ export const petstore: OpenAPIObject = {
             type: "string",
             enum: ["labrador", "carlin", "beagle"],
           },
+          temperament: {
+            type: "string",
+            enum: ["calm", "playful", "aggressive", "shy"],
+            nullable: true,
+          },
         },
-        required: ["type", "breed"],
+        required: ["type", "breed", "temperament"],
       },
       Dog: {
         description: "A dog, wooof.",
@@ -378,8 +383,13 @@ export const petstore: OpenAPIObject = {
             type: "string",
             enum: ["saimois", "bengal", "british shorthair"],
           },
+          temperament: {
+            type: "string",
+            enum: ["calm", "playful", "aggressive", "shy"],
+            nullable: true,
+          },
         },
-        required: ["type", "breed"],
+        required: ["type", "breed", "temperament"],
       },
       Error: {
         description: "An error :(",
diff --git a/plugins/typescript/src/generators/generateSchemaTypes.test.ts b/plugins/typescript/src/generators/generateSchemaTypes.test.ts
index 5bf29a6a..23c10120 100644
--- a/plugins/typescript/src/generators/generateSchemaTypes.test.ts
+++ b/plugins/typescript/src/generators/generateSchemaTypes.test.ts
@@ -175,6 +175,7 @@ describe("generateSchemaTypes", () => {
         export type Cat = {
           type: string;
           breed: "labrador" | "carlin" | "beagle";
+          temperament: "calm" | "playful" | "aggressive" | "shy" | null;
         };
 
         /**
@@ -183,6 +184,7 @@ describe("generateSchemaTypes", () => {
         export type Dog = {
           type: string;
           breed: "saimois" | "bengal" | "british shorthair";
+          temperament: "calm" | "playful" | "aggressive" | "shy" | null;
         };
 
         /**
@@ -233,13 +235,27 @@ describe("generateSchemaTypes", () => {
           Carlin = "carlin",
           Beagle = "beagle",
         }
-
+        
+        export enum CatTemperament {
+          Calm = "calm",
+          Playful = "playful",
+          Aggressive = "aggressive",
+          Shy = "shy",
+        }
+        
         export enum DogBreed {
           Saimois = "saimois",
           Bengal = "bengal",
           BritishShorthair = "british shorthair",
         }
-
+        
+        export enum DogTemperament {
+          Calm = "calm",
+          Playful = "playful",
+          Aggressive = "aggressive",
+          Shy = "shy",
+        }
+        
         /**
          * A new pet.
          */
@@ -275,6 +291,7 @@ describe("generateSchemaTypes", () => {
         export type Cat = {
           type: string;
           breed: CatBreed;
+          temperament: CatTemperament | null;
         };
 
         /**
@@ -283,6 +300,7 @@ describe("generateSchemaTypes", () => {
         export type Dog = {
           type: string;
           breed: DogBreed;
+          temperament: DogTemperament | null;
         };
 
         /**