From 0ac27fc817eb15c64f57981a93353023d2b96c34 Mon Sep 17 00:00:00 2001
From: Yusuke Wada <yusuke@kamawada.com>
Date: Tue, 29 Aug 2023 23:07:27 +0900
Subject: [PATCH] fix(types): infer a response type for async handler (#1385)

* fix(types): infer a response type for async handler

* denoify
---
 deno_dist/types.ts |  8 +++++++-
 src/types.test.ts  | 23 +++++++++++++++++++++++
 src/types.ts       |  8 +++++++-
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/deno_dist/types.ts b/deno_dist/types.ts
index 3586c6b8..de96806a 100644
--- a/deno_dist/types.ts
+++ b/deno_dist/types.ts
@@ -387,7 +387,13 @@ export type TypedResponse<T = unknown> = {
   format: 'json' // Currently, support only `json` with `c.jsonT()`
 }
 
-type ExtractResponseData<T> = T extends TypedResponse<infer U> ? U : never
+type ExtractResponseData<T> = T extends Promise<infer T2>
+  ? T2 extends TypedResponse<infer U>
+    ? U
+    : never
+  : T extends TypedResponse<infer U>
+  ? U
+  : never
 
 type MergeTypedResponseData<T> = UnionToIntersection<ExtractResponseData<T>>
 
diff --git a/src/types.test.ts b/src/types.test.ts
index 526cca04..564f0a8f 100644
--- a/src/types.test.ts
+++ b/src/types.test.ts
@@ -595,3 +595,26 @@ describe('Different types using jsonT()', () => {
     })
   })
 })
+
+describe('jsonT() in an async handler', () => {
+  const app = new Hono()
+  test('Three different types', () => {
+    const route = app.get(async (c) => {
+      return c.jsonT({
+        ok: true,
+      })
+    })
+    type Actual = ExtractSchema<typeof route>
+    type Expected = {
+      '/': {
+        $get: {
+          input: {}
+          output: {
+            ok: boolean
+          }
+        }
+      }
+    }
+    type verify = Expect<Equal<Expected, Actual>>
+  })
+})
diff --git a/src/types.ts b/src/types.ts
index 59786de7..d821c3d6 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -387,7 +387,13 @@ export type TypedResponse<T = unknown> = {
   format: 'json' // Currently, support only `json` with `c.jsonT()`
 }
 
-type ExtractResponseData<T> = T extends TypedResponse<infer U> ? U : never
+type ExtractResponseData<T> = T extends Promise<infer T2>
+  ? T2 extends TypedResponse<infer U>
+    ? U
+    : never
+  : T extends TypedResponse<infer U>
+  ? U
+  : never
 
 type MergeTypedResponseData<T> = UnionToIntersection<ExtractResponseData<T>>