Default mimetype when detection fails should be application/octet-stream

[AbdealiLoKo]

Hi, I'm a long time flask and django user. I was trying out fastapi and was trying out some StaticFile stuff when I noticed some differences. Wanted to highlight them here to understand whether the behavior should be changed

When I use the starlette.responses.FileResponse class I noticed that when I was sending binary files, I was receiving a contentType as text/plain.

On digging into it, I noticed this was causing it: https://github.com/Kludex/starlette/blob/0.51.0/starlette/responses.py#L317

I was wondering if it was a purposeful decision and whether I could change the default ... and noticed this issue: #1027 (comment)
Where the discussion was about trying to follow flask/django's standard in such cases for UploadedFiles.

I see that both Django and Flask are using application/octet-stream in these cases:
Django: https://github.com/django/django/blob/6.0.1/django/views/static.py#L59
Flask / Werkzeug: https://github.com/pallets/werkzeug/blob/3.1.5/src/werkzeug/utils.py#L441

Workaround: For now, I am explicitly sending the mimetype myself. And that got my UI working...

Long Term: I was curious to learn if there was a reason to keep text/plain as the default. And whether I should be handling this in some other place in my stack like in the UI etc.