From d2dd6b43bd6180797325fab06d8696b66e2e9f59 Mon Sep 17 00:00:00 2001
From: Sahariar Hasan <sahariarhasan83@gmail.com>
Date: Mon, 19 Oct 2026 00:13:15 +0530
Subject: [PATCH 1/2] feat(dx): add @app.exception_handler decorator syntax

Add decorator-based global exception handler registration while preserving the existing imperative API.

Closes #274
---
 oxyroute/app.py                  | 19 +++++++++++++++++++
 tests/test_exception_handlers.py | 32 +++++++++++++++++++++++++++-----
 2 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/oxyroute/app.py b/oxyroute/app.py
index 2e48ced..0a4710c 100644
--- a/oxyroute/app.py
+++ b/oxyroute/app.py
@@ -383,6 +383,25 @@ def add_exception_handler(
         """
         self._app.add_exception_handler(exc_type, handler)
 
+    def exception_handler(
+        self, exc_type: type[BaseException]
+    ) -> Callable[[Callable[..., Any]], Callable[..., Any]]:
+        """
+        Decorator to register a global exception handler for a specific exception type.
+
+        Example::
+
+            @app.exception_handler(ValueError)
+            def handle_value_error(request, exc: ValueError):
+                return {"detail": str(exc)}, 400
+        """
+
+        def decorator(handler: Callable[..., Any]) -> Callable[..., Any]:
+            self.add_exception_handler(exc_type, handler)
+            return handler
+
+        return decorator
+
     def set_middleware(self, handler: Callable[..., Any] | None) -> None:
         """
         One optional pre-route callback ``(scope, protocol)`` — return ``None`` to pass through.
diff --git a/tests/test_exception_handlers.py b/tests/test_exception_handlers.py
index 69c6ed7..8167176 100644
--- a/tests/test_exception_handlers.py
+++ b/tests/test_exception_handlers.py
@@ -15,11 +15,6 @@ class SubCustomError(CustomError):
 
     app = App()
 
-    # Note: the `add_exception_handler` method might be used as a decorator or a regular method.
-    # We didn't implement it as a decorator returning the function, but in our `app.py` it's just:
-    # def add_exception_handler(self, exc_type: type[BaseException], handler: Callable[..., Any]) -> None:
-    # So we call it directly.
-
     def handle_custom_error(scope, exc):
         return Response(status=400, body=exc.msg.encode())
 
@@ -56,3 +51,30 @@ async def _run() -> None:
             assert r3.status_code == 500
 
     asyncio.run(_run())
+
+
+def test_exception_handler_decorator():
+    """@app.exception_handler(exc_type) decorator syntax (issue #274)."""
+
+    class DecoratorError(Exception):
+        def __init__(self, msg: str):
+            self.msg = msg
+
+    app = App()
+
+    @app.exception_handler(DecoratorError)
+    def handle_decorator_error(scope, exc: DecoratorError):
+        return Response(status=422, body=f"decorated:{exc.msg}".encode())
+
+    @app.get("/decorated-error")
+    def raise_decorated() -> str:
+        raise DecoratorError("via-decorator")
+
+    async def _run() -> None:
+        transport = httpx.ASGITransport(app=asgi_test_app(app))
+        async with httpx.AsyncClient(transport=transport, base_url="http://test") as c:
+            r = await c.get("/decorated-error")
+            assert r.status_code == 422
+            assert r.text == "decorated:via-decorator"
+
+    asyncio.run(_run())

From 115f214bf4887eb00927006f0742c92eacec1c0a Mon Sep 17 00:00:00 2001
From: ZhuchkaTriplesix <mrlololoshka94@gmail.com>
Date: Sun, 18 Oct 2026 22:26:29 +0300
Subject: [PATCH 2/2] fix(dx): preserve handler types and update docstring
 example

---
 oxyroute/app.py | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/oxyroute/app.py b/oxyroute/app.py
index 0a4710c..f029f79 100644
--- a/oxyroute/app.py
+++ b/oxyroute/app.py
@@ -383,20 +383,18 @@ def add_exception_handler(
         """
         self._app.add_exception_handler(exc_type, handler)
 
-    def exception_handler(
-        self, exc_type: type[BaseException]
-    ) -> Callable[[Callable[..., Any]], Callable[..., Any]]:
+    def exception_handler(self, exc_type: type[BaseException]) -> Callable[[F], F]:
         """
         Decorator to register a global exception handler for a specific exception type.
 
         Example::
 
             @app.exception_handler(ValueError)
-            def handle_value_error(request, exc: ValueError):
-                return {"detail": str(exc)}, 400
+            def handle_value_error(scope, exc: ValueError):
+                return Response(status=400, body=str(exc).encode())
         """
 
-        def decorator(handler: Callable[..., Any]) -> Callable[..., Any]:
+        def decorator(handler: F) -> F:
             self.add_exception_handler(exc_type, handler)
             return handler