FileResponse: accept BufferedReader

[Derkades]

What do these changes do?

FileResponse now accepts an opened file instead of only a file path. This allows sending a temporary file to the client by opening the file, deleting it, and then passing the open file to FileResponse. FileResponse handles closing the file when it is no longer used.

This is a proof of concept, I am not sure if this is the best way to solve this problem.

Are there changes in behavior for the user?

No breaking changes.

Is it a substantial burden for the maintainers to support this?

The FileResponse class is now more complicated. I am still thinking about if it makes sense to split FileResponse into two classes, one for handling IO and one for handling paths.

It is a bit unusual for an API to take an open file and close it by itself. But it solves a problem. Other suggestions are welcome.

Related issue number

#10360

Checklist

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[codspeed-hq]

CodSpeed Performance Report

Merging #10465 will not alter performance

_{Comparing Derkades:fileresponse-bufferedreader (c7de271) with master (e29d989)}

Summary

✅ 46 untouched benchmarks

[Dreamsorcerer]

Unless I'm missing something, it seems like FileResponse is missing Content-Disposition by default. If we were to add this in and recommend the user to specify a filename for the download, then we could use that filename here (or just use it if the header has been explicitly passed):

>>> mimetypes.guess_type("foo.html")
('text/html', None)

[Dreamsorcerer]

I think this looks reasonable. I suspect a subclass may be cleaner though (FileIOResponse maybe?).