From fdf66c825ed70da423724180e91b02345aa36326 Mon Sep 17 00:00:00 2001
From: Sharon Yogev <31185192+sharonyogev@users.noreply.github.com>
Date: Thu, 13 Apr 2023 20:49:22 +0300
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20Fix=20using=20`Annotated`=20in?=
 =?UTF-8?q?=20routers=20or=20path=20operations=20decorated=20multiple=20ti?=
 =?UTF-8?q?mes=20(#9315)?=
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* Fix: copy FieldInfo from Annotated arguments

We need to copy the field_info to prevent ourselves from
mutating it.  This allows multiple path or nested routers ,etc.

* 📝 Add comment in fastapi/dependencies/utils.py

Co-authored-by: Nadav Zingerman <7372858+nzig@users.noreply.github.com>

* ✅ Extend and tweak tests for Annotated

* ✅ Tweak coverage, it's probably covered by a different version of Python

---------

Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>
Co-authored-by: Nadav Zingerman <7372858+nzig@users.noreply.github.com>
---
 fastapi/dependencies/utils.py |  5 ++--
 tests/test_annotated.py       | 43 ++++++++++++++++++++++++++++++++++-
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index c581348c9..f131001ce 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -1,7 +1,7 @@
 import dataclasses
 import inspect
 from contextlib import contextmanager
-from copy import deepcopy
+from copy import copy, deepcopy
 from typing import (
     Any,
     Callable,
@@ -383,7 +383,8 @@ def analyze_param(
         ), f"Cannot specify multiple `Annotated` FastAPI arguments for {param_name!r}"
         fastapi_annotation = next(iter(fastapi_annotations), None)
         if isinstance(fastapi_annotation, FieldInfo):
-            field_info = fastapi_annotation
+            # Copy `field_info` because we mutate `field_info.default` below.
+            field_info = copy(fastapi_annotation)
             assert field_info.default is Undefined or field_info.default is Required, (
                 f"`{field_info.__class__.__name__}` default value cannot be set in"
                 f" `Annotated` for {param_name!r}. Set the default value with `=` instead."
diff --git a/tests/test_annotated.py b/tests/test_annotated.py
index 556019897..30c8efe01 100644
--- a/tests/test_annotated.py
+++ b/tests/test_annotated.py
@@ -1,5 +1,5 @@
 import pytest
-from fastapi import FastAPI, Query
+from fastapi import APIRouter, FastAPI, Query
 from fastapi.testclient import TestClient
 from typing_extensions import Annotated
 
@@ -224,3 +224,44 @@ def test_get(path, expected_status, expected_response):
     response = client.get(path)
     assert response.status_code == expected_status
     assert response.json() == expected_response
+
+
+def test_multiple_path():
+    @app.get("/test1")
+    @app.get("/test2")
+    async def test(var: Annotated[str, Query()] = "bar"):
+        return {"foo": var}
+
+    response = client.get("/test1")
+    assert response.status_code == 200
+    assert response.json() == {"foo": "bar"}
+
+    response = client.get("/test1", params={"var": "baz"})
+    assert response.status_code == 200
+    assert response.json() == {"foo": "baz"}
+
+    response = client.get("/test2")
+    assert response.status_code == 200
+    assert response.json() == {"foo": "bar"}
+
+    response = client.get("/test2", params={"var": "baz"})
+    assert response.status_code == 200
+    assert response.json() == {"foo": "baz"}
+
+
+def test_nested_router():
+    app = FastAPI()
+
+    router = APIRouter(prefix="/nested")
+
+    @router.get("/test")
+    async def test(var: Annotated[str, Query()] = "bar"):
+        return {"foo": var}
+
+    app.include_router(router)
+
+    client = TestClient(app)
+
+    response = client.get("/nested/test")
+    assert response.status_code == 200
+    assert response.json() == {"foo": "bar"}