From 634cf22584fc4fd9ee53cfdf0ad6d48a2830ac34 Mon Sep 17 00:00:00 2001
From: Taneli Hukkinen <3275109+hukkin@users.noreply.github.com>
Date: Mon, 22 Aug 2022 22:17:45 +0300
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20Fix=20`response=5Fmodel`=20not?=
 =?UTF-8?q?=20invalidating=20`None`=20(#2725)?=
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Co-authored-by: Taneli Hukkinen <hukkinj1@users.noreply.github.com>
Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>
---
 fastapi/utils.py                |  2 +-
 tests/test_validate_response.py | 34 ++++++++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/fastapi/utils.py b/fastapi/utils.py
index 887d57c90..40750a5b3 100644
--- a/fastapi/utils.py
+++ b/fastapi/utils.py
@@ -50,7 +50,7 @@ def create_response_field(
     type_: Type[Any],
     class_validators: Optional[Dict[str, Validator]] = None,
     default: Optional[Any] = None,
-    required: Union[bool, UndefinedType] = False,
+    required: Union[bool, UndefinedType] = True,
     model_config: Type[BaseConfig] = BaseConfig,
     field_info: Optional[FieldInfo] = None,
     alias: Optional[str] = None,
diff --git a/tests/test_validate_response.py b/tests/test_validate_response.py
index 45d303e20..62f51c960 100644
--- a/tests/test_validate_response.py
+++ b/tests/test_validate_response.py
@@ -1,4 +1,4 @@
-from typing import List, Optional
+from typing import List, Optional, Union
 
 import pytest
 from fastapi import FastAPI
@@ -19,6 +19,19 @@ def get_invalid():
     return {"name": "invalid", "price": "foo"}
 
 
+@app.get("/items/invalidnone", response_model=Item)
+def get_invalid_none():
+    return None
+
+
+@app.get("/items/validnone", response_model=Union[Item, None])
+def get_valid_none(send_none: bool = False):
+    if send_none:
+        return None
+    else:
+        return {"name": "invalid", "price": 3.2}
+
+
 @app.get("/items/innerinvalid", response_model=Item)
 def get_innerinvalid():
     return {"name": "double invalid", "price": "foo", "owner_ids": ["foo", "bar"]}
@@ -41,6 +54,25 @@ def test_invalid():
         client.get("/items/invalid")
 
 
+def test_invalid_none():
+    with pytest.raises(ValidationError):
+        client.get("/items/invalidnone")
+
+
+def test_valid_none_data():
+    response = client.get("/items/validnone")
+    data = response.json()
+    assert response.status_code == 200
+    assert data == {"name": "invalid", "price": 3.2, "owner_ids": None}
+
+
+def test_valid_none_none():
+    response = client.get("/items/validnone", params={"send_none": "true"})
+    data = response.json()
+    assert response.status_code == 200
+    assert data is None
+
+
 def test_double_invalid():
     with pytest.raises(ValidationError):
         client.get("/items/innerinvalid")