🐛 Fix File field cannot be defined after Form field

fastapi/dependencies/utils.py

@@ -713,6 +713,7 @@ async def request_body_to_args(
                     except AttributeError:
                         errors.append(get_missing_field_error(loc))
                         continue
+            field_info = field.field_info
             if (
                 value is None
                 or (isinstance(field_info, params.Form) and value == "")

tests/test_datastructures.py

@@ -3,7 +3,7 @@ from pathlib import Path
 from typing import List
 
 import pytest
-from fastapi import FastAPI, UploadFile
+from fastapi import FastAPI, File, Form, UploadFile
 from fastapi.datastructures import Default
 from fastapi.testclient import TestClient
 
@@ -33,10 +33,22 @@ def test_default_placeholder_bool():
     assert not placeholder_b
 
 
-def test_upload_file_is_closed(tmp_path: Path):
-    path = tmp_path / "test.txt"
-    path.write_bytes(b"<file content>")
+@pytest.fixture(name="client", scope="module")
+def get_client():
     app = FastAPI()
+    client = TestClient(app)
+    return client
+
+
+@pytest.fixture(scope="module")
+def tmp_file(tmp_path_factory):
+    path = tmp_path_factory.getbasetemp() / "test.txt"
+    path.write_bytes(b"<file content>")
+    return path
+
+
+def test_upload_file_is_closed(client: TestClient, tmp_file: Path):
+    app = client.app
 
     testing_file_store: List[UploadFile] = []
 
@@ -46,7 +58,7 @@ def test_upload_file_is_closed(tmp_path: Path):
         return {"filename": file.filename}
 
     client = TestClient(app)
-    with path.open("rb") as file:
+    with tmp_file.open("rb") as file:
         response = client.post("/uploadfile/", files={"file": file})
     assert response.status_code == 200, response.text
     assert response.json() == {"filename": "test.txt"}
@@ -55,6 +67,26 @@ def test_upload_file_is_closed(tmp_path: Path):
     assert testing_file_store[0].file.closed
 
 
+def test_form_is_declared_before_file(client: TestClient, tmp_file: Path):
+    app = client.app
+
+    @app.post("/uploadfile_checksum/")
+    def create_upload_file_with_checksum(
+        checksum: str = Form(), file: UploadFile = File()
+    ):
+        return {"checksum": checksum, "filename": file.filename}
+
+    client = TestClient(app)
+    with tmp_file.open("rb") as file:
+        response = client.post(
+            "/uploadfile_checksum/",
+            data={"checksum": "<file hash>"},
+            files={"file": file},
+        )
+    assert response.status_code == 200, response.text
+    assert response.json() == {"checksum": "<file hash>", "filename": "test.txt"}
+
+
 # For UploadFile coverage, segments copied from Starlette tests