From bc8052a196e9e9e574acad17e2c4ab02666a17b9 Mon Sep 17 00:00:00 2001
From: Gabriel Soicher <gabe@underware.co.za>
Date: Wed, 27 Oct 2021 09:18:17 +0200
Subject: [PATCH] Add read_with_orm_mode for dataclasses

This allows for a workaround for SQLAlchemy dataclasses after the changes introduced in 0.67 .

It replicates the funcionality provided for Pydantic models (`read_with_orm_mode`) by allowing a special property to be set on dataclasses that want to opt in to the feature.
---
 fastapi/routing.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fastapi/routing.py b/fastapi/routing.py
index 63ad72964..607410e0b 100644
--- a/fastapi/routing.py
+++ b/fastapi/routing.py
@@ -99,6 +99,11 @@ def _prepare_response_content(
             for k, v in res.items()
         }
     elif dataclasses.is_dataclass(res):
+        # Allow dataclasses to specify the same read_with_orm_mode property as
+        # Pydantic models above
+        read_with_orm_mode = getattr(res, "__read_with_orm_mode__", None)
+        if read_with_orm_mode:
+            return res
         return dataclasses.asdict(res)
     return res