Can anyone suggest, with a SuiteLet that has a file upload field, how to know the file type to create it in the filecabinet? I'd prefer to avoid using the filename suffix if possible.

although probably based on the filename, the type should already be on the file object from ServerRequest.files

i just realised my error, I used .type thanks @battk

Usually you just set the folder and save the file

That's good to know thanks, I'm actually sending an email and the files are attachments, initially I thought I'd need to save the files in the filecabinet.