python data_error ai_generated true

fastapi.exceptions.RequestValidationError: [{'type': 'value_error.missing', 'loc': ['body', 'file'], 'msg': 'field required', 'input': None}]

ID: python/fastapi-file-upload-empty

Also available as: JSON · Markdown · 中文
80%Fix Rate
86%Confidence
0Evidence
2024-03-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.x active — — —

Root Cause

The endpoint expects a file upload via `UploadFile` but the request doesn't include a file part in the multipart form data.

generic

中文

端点期望通过`UploadFile`上传文件，但请求的multipart表单数据中没有包含文件部分。

Workarounds

  1. 95% success 
    Ensure the client sends multipart form data with the correct field name. For testing: `client.post('/upload', files={'file': ('filename.txt', b'content', 'text/plain')})`.
  2. 90% success 
    Make the file parameter optional: `file: UploadFile = File(None)`.

Dead Ends

Common approaches that don't work:

  1. 95% fail

    Sending the file as a JSON body doesn't work; FastAPI expects multipart form data.

  2. 80% fail

    Using `requests.post(url, files={'file': open('file.txt', 'rb')})` may fail if the field name doesn't match the parameter name.