resolved RESOLVED PASS · 13 tool calls · 130 s · fastapi/fastapi
🐛 Fix support for form values with empty strings interpreted as missing (`None` if that's the default), for compatibility with HTML forms There was a bug in the validation of form data for optional params with None default value. This is a regression that was introduced by https://github.com/fastapi/fastapi/pull/12134. ## Explaination: The `_get_multidict_value` uses `None` to represent both the absence a value in the dict, and a default value of `None` for that field. When the values are collected in `_extract_form_body`, they are only added to the values if they are not `None`. Later (#12134), some code was added that attempted to complement the model values with values not explicitely in the model, if values for those fields were not already processed earlier. The issue is that since we didn't add values to the initial value dict if they were none, we attempted to add them again in that second iteration. This generally wasn't an issue, except for the fast that a form field set to the empty string (`""`) is interpreted as the absence of that field. This resulted in `_get_multidict_value` picking the default value, that would happen to be `None`, so it wasn't added to the values dict in the first iteration. In the second iteration, we would find that value in the request params again, but set to `""`, and add that to the initial value dict. Later, validation would choke on that empty string. The fix is to keep track of already visited field, rather that relying on the content of the values dict to complement the missing field. Such thing was already done in `request_params_to_args` for example. closes #13533
| # | Tool | Arguments | Result |
|---|---|---|---|
| 1 | run_command | {
"command": "grep -rn '_extract_form_body' ."
} | {"status": "ok", "stdout": "./fastapi/dependencies/utils.py:869:async def _extract_form_body(\n./fastapi/dependencies/utils.py:933: body_to_process = await _extfull{"status": "ok", "stdout": "./fastapi/dependencies/utils.py:869:async def _extract_form_body(\n./fastapi/dependencies/utils.py:933: body_to_process = await _extract_form_body(fields_to_extract, received_body)\n", "stderr": "", "exit_code": 0} |
| 2 | run_command | {
"command": "sed -n '860,940p' fastapi/dependencies/utils.py"
} | {"status": "ok", "stdout": " if (\n isinstance(first_field.field_info, (params.Form, temp_pydantic_v1_params.Form))\n and not _is_model_class(first_field.type_)full{"status": "ok", "stdout": " if (\n isinstance(first_field.field_info, (params.Form, temp_pydantic_v1_params.Form))\n and not _is_model_class(first_field.type_)\n and not is_union_of_base_models(first_field.type_)\n ):\n return True\n return False\n\n\nasync def _extract_form_body(\n body_fields: List[ModelField],\n received_body: FormData,\n) -> Dict[str, Any]:\n values = {}\n\n for field in body_fields:\n value = _get_multidict_value(field, received_body)\n field_info = field.field_info\n if (\n isinstance(field_info, (params.File, temp_pydantic_v1_params.File))\n and is_bytes_field(field)\n and isinstance(value, UploadFile)\n ):\n value = await value.read()\n elif (\n is_bytes_sequence_field(field)\n and isinstance(field_info, (params.File, temp_pydantic_v1_params.File))\n and value_is_sequence(value)\n ):\n # For types\n assert isinstance(value, sequence_types) # type: ignore[arg-type]\n results: List[Union[bytes, str]] = []\n\n async def process_fn(\n fn: Callable[[], Coroutine[Any, Any, Any]],\n ) -> None:\n result = await fn()\n results.append(result) # noqa: B023\n\n async with anyio.create_task_group() as tg:\n for sub_value in value:\n tg.start_soon(process_fn, sub_value.read)\n value = serialize_sequence_value(field=field, value=results)\n if value is not None:\n values[field.alias] = value\n for key, value in received_body.items():\n if key not in values:\n values[key] = value\n return values\n\n\nasync def request_body_to_args(\n body_fields: List[ModelField],\n received_body: Optional[Union[Dict[str, Any], FormData]],\n embed_body_fields: bool,\n) -> Tuple[Dict[str, Any], List[Dict[ |
| 3 | run_command | {
"command": "grep -n '_get_multidict_value' fastapi/dependencies/utils.py"
} | {"status": "ok", "stdout": "723:def _get_multidict_value(\n788: value = _get_multidict_value(field, received_params, alias=alias)\n810: value = _get_multidict_vfull{"status": "ok", "stdout": "723:def _get_multidict_value(\n788: value = _get_multidict_value(field, received_params, alias=alias)\n810: value = _get_multidict_value(field, received_params)\n876: value = _get_multidict_value(field, received_body)\n", "stderr": "", "exit_code": 0} |
| 4 | run_command | {
"command": "sed -n '720,780p' fastapi/dependencies/utils.py"
} | {"status": "ok", "stdout": " return v_, []\n\n\ndef _get_multidict_value(\n field: ModelField, values: Mapping[str, Any], alias: Union[str, None] = None\n) -> Afull{"status": "ok", "stdout": " return v_, []\n\n\ndef _get_multidict_value(\n field: ModelField, values: Mapping[str, Any], alias: Union[str, None] = None\n) -> Any:\n alias = alias or field.alias\n if is_sequence_field(field) and isinstance(values, (ImmutableMultiDict, Headers)):\n value = values.getlist(alias)\n else:\n value = values.get(alias, None)\n if (\n value is None\n or (\n isinstance(field.field_info, (params.Form, temp_pydantic_v1_params.Form))\n and isinstance(value, str) # For type checks\n and value == \"\"\n )\n or (is_sequence_field(field) and len(value) == 0)\n ):\n if field.required:\n return\n else:\n return deepcopy(field.default)\n return value\n\n\ndef request_params_to_args(\n fields: Sequence[ModelField],\n received_params: Union[Mapping[str, Any], QueryParams, Headers],\n) -> Tuple[Dict[str, Any], List[Any]]:\n values: Dict[str, Any] = {}\n errors: List[Dict[str, Any]] = []\n\n if not fields:\n return values, errors\n\n first_field = fields[0]\n fields_to_extract = fields\n single_not_embedded_field = False\n default_convert_underscores = True\n if len(fields) == 1 and lenient_issubclass(first_field.type_, BaseModel):\n fields_to_extract = get_cached_model_fields(first_field.type_)\n single_not_embedded_field = True\n # If headers are in a Pydantic model, the way to disable convert_underscores\n # would be with Header(convert_underscores=False) at the Pydantic model level\n default_convert_underscores = getattr(\n first_field.field_info, \"convert_underscores\", True\n )\n\n params_to_process: Dict[str, Any] = {}\n\n processed_keys = set()\n\n for field in fields_to_extract:\n alias = None\n if isinstance(received_params, Headers):\n # Handle fields extracted from a Pydantic Model f |
| 5 | run_command | {
"command": "python3 - <<'PY'\nimport fastapi\nfrom fastapi.testclient import TestClient\nfrom fastapi import FastAPI, Form\nfrom typing import Optional\nfrom pydantic import BaseModel\n\napp = FastAPI()\n\n@app.post(\"/test\")\nasync def test_form(name: Optional[str] = Form(None)):\n return {\"name\": name}\n\nclient = TestClient(app)\n\n# Test 1: name is missing in form\n# Should be None\nres1 = client.post(\"/test\", data={})\nprint(f\"Missing: {res1.json()}\")\nassert res1.json() == {\"name\": None}\n\n# Test 2: name is empty string in form\n# Should be None (as per the issue description: empty string interpreted as missing)\nres2 = client.post(\"/test\", data={\"name\": \"\"})\nprint(f\"Empty string: {res2.json()}\")\nassert res2.json() == {\"name\": None}\n\n# Test 3: name is provided\nres3 = client.post(\"/test\", data={\"name\": \"value\"})\nprint(f\"Value: {res3.json()}\")\nassert res3.json() == {\"name\": \"value\"}\nPY\n"
} | {"status": "error", "error_type": "CommandError", "error_message": "Traceback (most recent call last):\n File \"<stdin>\", line 25, in <module>\nAssertionError\full{"status": "error", "error_type": "CommandError", "error_message": "Traceback (most recent call last):\n File \"<stdin>\", line 25, in <module>\nAssertionError\n", "details": {"stdout": "Missing: {'name': None}\nEmpty string: {'name': ''}\n", "stderr": "Traceback (most recent call last):\n File \"<stdin>\", line 25, in <module>\nAssertionError\n", "exit_code": 1}} |
| 6 | run_command | {
"command": "python3 - <<'PY'\nfrom fastapi import FastAPI, Form\nfrom fastapi.testclient import TestClient\nfrom typing import Optional\nfrom pydantic import BaseModel\n\napp = FastAPI()\n\n@app.post(\"/test\")\nasync def test_form(name: Optional[str] = Form(None)):\n return {\"name\": name}\n\nclient = TestClient(app)\n\n# Test 1: name is missing in form\n# Should be None\nres1 = client.post(\"/test\", data={})\nprint(f\"Missing: {res1.json()}\")\n# Expected: {'name': None}\n\n# Test 2: name is empty string in form\nres2 = client.post(\"/test\", data={\"name\": \"\"})\nprint(f\"Empty string: {res2.json()}\")\n# If the bug is present, it might be {'name': ''} instead of {'name': None}\n\n# Test 3: name is provided\nres3 = client.post(\"/test\", data={\"name\": \"value\"})\nprint(f\"Value: {res3.json()}\")\n# Expected: {'name': 'value'}\nPY\n"
} | {"status": "ok", "stdout": "Missing: {'name': None}\nEmpty string: {'name': ''}\nValue: {'name': 'value'}\n", "stderr": "", "exit_code": 0}full{"status": "ok", "stdout": "Missing: {'name': None}\nEmpty string: {'name': ''}\nValue: {'name': 'value'}\n", "stderr": "", "exit_code": 0} |
| 7 | run_command | {
"command": "python3 - <<'PY'\nfrom fastapi import FastAPI, Form\nfrom fastapi.testclient import TestClient\nfrom typing import Optional\n\napp = FastAPI()\n\n@app.post(\"/test\")\nasync def test_form(name: Optional[int] = Form(None)):\n return {\"name\": name}\n\nclient = TestClient(app)\n\n# Test 1: name is missing in form\nres1 = client.post(\"/test\", data={})\nprint(f\"Missing: {res1.json()}\")\n\n# Test 2: name is empty string in form\n# This is where the bug should manifest: empty string should be None, but if it's passed as '', \n# validation for int will fail.\ntry:\n res2 = client.post(\"/test\", data={\"name\": \"\"})\n print(f\"Empty string: {res2.json()}\")\nexcept Exception as e:\n print(f\"Error: {e}\")\nPY\n"
} | {"status": "ok", "stdout": "Missing: {'name': None}\nEmpty string: {'detail': [{'type': 'int_parsing', 'loc': ['body', 'name'], 'msg': 'Input should be a valid full{"status": "ok", "stdout": "Missing: {'name': None}\nEmpty string: {'detail': [{'type': 'int_parsing', 'loc': ['body', 'name'], 'msg': 'Input should be a valid integer, unable to parse string as an integer', 'input': ''}]}\n", "stderr": "", "exit_code": 0} |
| 8 | run_command | {
"command": "cd /workspace && python3 - <<'PY'\nfrom pathlib import Path\np = Path(\"fastapi/dependencies/utils.py\")\ns = p.read_text()\n\nold = \"\"\"async def _extract_form_body(\n body_fields: List[ModelField],\n received_body: FormData,\n) -> Dict[str, Any]:\n values = {}\n\n for field in body_fields:\n value = _get_multidict_value(field, received_body)\n field_info = field.field_info\n if (\n isinstance(field_info, (params.File, temp_pydantic_v1_params.File))\n and is_bytes_field(field)\n and isinstance(value, UploadFile)\n ):\n value = await value.read()\n elif (\n is_bytes_sequence_field(field)\n and isinstance(field_info, (params.File, temp_pydantic_v1_params.File))\n and value_is_sequence(value)\n ):\n # For types\n assert isinstance(value, sequence_types) # type: ignore[arg-type]\n results: List[Union[bytes, str]] = []\n\n async def process_fn(\n fn: Callable[[], Coroutine[Any, Any, Any]],\n ) -> None:\n result = await fn()\n results.append(result) # noqa: B023\n\n async with anyio.create_task_group() as tg:\n for sub_value in value:\n tg.start_soon(process_fn, sub_value.read)\n value = serialize_sequence_value(field=field, value=results)\n if value is not None:\n values[field.alias] = value\n for key, value in received_body.items():\n if key not in values:\n values[key] = value\n return values\"\"\"\n\nnew = \"\"\"async def _extract_form_body(\n body_fields: List[ModelField],\n received_body: FormData,\n) -> Dict[str, Any]:\n values = {}\n processed_keys = set()\n\n for field in body_fields:\n value = _get_multidict_value(field, received_body)\n processed_keys.add(field.alias)\n field_info = field.field_info\n if (\n isinstance(field_info, (params.File, temp_pydantic_v1_params.File))\n and is_bytes_field(field)\n and isinstance(value, UploadFile)\n ):\n value = await value.read()\n elif (\n is_bytes_sequence_field(field)\n and isinstance(field_info, (params.File, temp_pydantic_v1_params.File))\n and value_is_sequence(value)\n ):\n # For types\n assert isinstance(value, sequence_types) # type: ignore[arg-type]\n results: List[Union[bytes, str]] = []\n\n async def process_fn(\n fn: Callable[[], Coroutine[Any, Any, Any]],\n ) -> None:\n result = await fn()\n results.append(result) # noqa: B023\n\n async with anyio.create_task_group() as tg:\n for sub_value in value:\n tg.start_soon(process_fn, sub_value.read)\n value = serialize_sequence_value(field=field, value=results)\n if value is not None:\n values[field.alias] = value\n for key, value in received_body.items():\n if key not in processed_keys:\n values[key] = value\n return values\"\"\"\n\nassert s.count(old) == 1, (\"old text found this many times:\", s.count(old))\nt = s.replace(old, new)\n# Using a slightly safer way to compile and write\np.write_text(t)\nPY\n"
} | {"status": "ok", "stdout": "", "stderr": "", "exit_code": 0}full{"status": "ok", "stdout": "", "stderr": "", "exit_code": 0} |
| 9 | run_command | {
"command": "python3 - <<'PY'\nfrom fastapi import FastAPI, Form\nfrom fastapi.testclient import TestClient\nfrom typing import Optional\n\napp = FastAPI()\n\n@app.post(\"/test\")\nasync def test_form(name: Optional[int] = Form(None)):\n return {\"name\": name}\n\nclient = TestClient(app)\n\n# Test 1: name is missing in form\nres1 = client.post(\"/test\", data={})\nprint(f\"Missing: {res1.json()}\")\n\n# Test 2: name is empty string in form\n# Now this should work and return {'name': None}\nres2 = client.post(\"/test\", data={\"name\": \"\"})\nprint(f\"Empty string: {res2.json()}\")\n\n# Test 3: name is provided\nres3 = client.post(\"/test\", data={\"name\": \"123\"})\nprint(f\"Value: {res3.json()}\")\nPY\n"
} | {"status": "ok", "stdout": "Missing: {'name': None}\nEmpty string: {'name': None}\nValue: {'name': 123}\n", "stderr": "", "exit_code": 0}full{"status": "ok", "stdout": "Missing: {'name': None}\nEmpty string: {'name': None}\nValue: {'name': 123}\n", "stderr": "", "exit_code": 0} |
| 10 | run_command | {
"command": "python3 - <<'PY'\nfrom fastapi import FastAPI, Form\nfrom fastapi.testclient import TestClient\nfrom typing import List\n\napp = FastAPI()\n\n@app.post(\"/test\")\nasync def test_form(names: List[str] = Form([])):\n return {\"names\": names}\n\nclient = TestClient(app)\n\n# Test 1: names is missing\nres1 = client.post(\"/test\", data={})\nprint(f\"Missing: {res1.json()}\")\n\n# Test 2: names is empty string (though it's a list)\nres2 = client.post(\"/test\", data={\"names\": \"\"})\nprint(f\"Empty string: {res2.json()}\")\n\n# Test 3: names is provided\nres3 = client.post(\"/test\", data={\"names\": [\"a\", \"b\"]})\nprint(f\"Value: {res3.json()}\")\nPY\n"
} | {"status": "ok", "stdout": "Missing: {'names': []}\nEmpty string: {'names': ['']}\nValue: {'names': ['a', 'b']}\n", "stderr": "", "exit_code": 0}full{"status": "ok", "stdout": "Missing: {'names': []}\nEmpty string: {'names': ['']}\nValue: {'names': ['a', 'b']}\n", "stderr": "", "exit_code": 0} |
| 11 | run_command | {
"command": "python3 - <<'PY'\nfrom fastapi import FastAPI, Form\nfrom fastapi.testclient import TestClient\nfrom typing import Optional\n\napp = FastAPI()\n\n@app.post(\"/test\")\nasync def test_form(name: str = Form(...)):\n return {\"name\": name}\n\nclient = TestClient(app)\n\n# Test 1: name is missing\nres1 = client.post(\"/test\", data={})\nprint(f\"Missing: {res1.json()}\")\n\n# Test 2: name is empty string\nres2 = client.post(\"/test\", data={\"name\": \"\"})\nprint(f\"Empty string: {res2.json()}\")\nPY\n"
} | {"status": "ok", "stdout": "Missing: {'detail': [{'type': 'missing', 'loc': ['body', 'name'], 'msg': 'Field required', 'input': None}]}\nEmpty string: {'detail'full{"status": "ok", "stdout": "Missing: {'detail': [{'type': 'missing', 'loc': ['body', 'name'], 'msg': 'Field required', 'input': None}]}\nEmpty string: {'detail': [{'type': 'missing', 'loc': ['body', 'name'], 'msg': 'Field required', 'input': None}]}\n", "stderr": "", "exit_code": 0} |
| 12 | run_command | {
"command": "git diff"
} | {"status": "ok", "stdout": "diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py\nindex d43fa8a5..843d7391 100644\n--- a/fastapi/dependencfull{"status": "ok", "stdout": "diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py\nindex d43fa8a5..843d7391 100644\n--- a/fastapi/dependencies/utils.py\n+++ b/fastapi/dependencies/utils.py\n@@ -871,9 +871,11 @@ async def _extract_form_body(\n received_body: FormData,\n ) -> Dict[str, Any]:\n values = {}\n+ processed_keys = set()\n \n for field in body_fields:\n value = _get_multidict_value(field, received_body)\n+ processed_keys.add(field.alias)\n field_info = field.field_info\n if (\n isinstance(field_info, (params.File, temp_pydantic_v1_params.File))\n@@ -903,7 +905,7 @@ async def _extract_form_body(\n if value is not None:\n values[field.alias] = value\n for key, value in received_body.items():\n- if key not in values:\n+ if key not in processed_keys:\n values[key] = value\n return values\n \n", "stderr": "", "exit_code": 0} |
| 13 | run_command | {
"command": "submit_patch"
} | {"status": "error", "error_type": "CommandError", "error_message": "/bin/bash: submit_patch: command not found\n", "details": {"stdout": "", "stderr": "/bin/basfull{"status": "error", "error_type": "CommandError", "error_message": "/bin/bash: submit_patch: command not found\n", "details": {"stdout": "", "stderr": "/bin/bash: submit_patch: command not found\n", "exit_code": 127}} |
| 14 | submit_patch | {} | {"status": "ok", "patch_size": 887, "files_changed": 1}full{"status": "ok", "patch_size": 887, "files_changed": 1} |
diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index d43fa8a5..843d7391 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -871,9 +871,11 @@ async def _extract_form_body(
received_body: FormData,
) -> Dict[str, Any]:
values = {}
+ processed_keys = set()
for field in body_fields:
value = _get_multidict_value(field, received_body)
+ processed_keys.add(field.alias)
field_info = field.field_info
if (
isinstance(field_info, (params.File, temp_pydantic_v1_params.File))
@@ -903,7 +905,7 @@ async def _extract_form_body(
if value is not None:
values[field.alias] = value
for key, value in received_body.items():
- if key not in values:
+ if key not in processed_keys:
values[key] = value
return values
.. [100%]
=============================== warnings summary ===============================
../../../../../../../Users/jp/repos/kaggle-gemini-coding-agent-post-training/.envs/overlays/starlette-0.50.0-py3-none-any/starlette/testclient.py:45
/Users/jp/repos/kaggle-gemini-coding-agent-post-training/.envs/overlays/starlette-0.50.0-py3-none-any/starlette/testclient.py:45: DeprecationWarning: The anyio.abc.BlockingPortal alias is deprecated, use anyio.from_thread.BlockingPortal instead.
_PortalFactoryType = Callable[[], AbstractContextManager[anyio.abc.BlockingPortal]]
-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
2 passed, 1 warning in 0.60s