Merge c524dd41e0 into 5420847d9f

fastapi/dependencies/utils.py

@@ -900,7 +900,10 @@ async def _extract_form_body(
             assert isinstance(value, sequence_types)
             results: list[bytes | str] = []
             for sub_value in value:
-                results.append(await sub_value.read())
+                if isinstance(sub_value, UploadFile):
+                    results.append(await sub_value.read())
+                else:
+                    results.append(sub_value)
             value = serialize_sequence_value(field=field, value=results)
         if value is not None:
             values[get_validation_alias(field)] = value

tests/test_optional_file_list.py

@@ -1,5 +1,3 @@
-from typing import Optional
-
 from fastapi import FastAPI, File
 from fastapi.testclient import TestClient
 
@@ -7,7 +5,7 @@ app = FastAPI()
 
 
 @app.post("/files")
-async def upload_files(files: Optional[list[bytes]] = File(None)):
+async def upload_files(files: list[bytes] | None = File(None)):
     if files is None:
         return {"files_count": 0}
     return {"files_count": len(files), "sizes": [len(f) for f in files]}
@@ -28,3 +26,13 @@ def test_optional_bytes_list_no_files():
     response = client.post("/files")
     assert response.status_code == 200
     assert response.json() == {"files_count": 0}
+
+
+def test_optional_bytes_list_send_empty_str():
+    client = TestClient(app)
+    response = client.post(
+        "/files",
+        data={"files": ""},
+    )
+    assert response.status_code == 200
+    assert response.json() == {"files_count": 1, "sizes": [0]}