Multiple Non-Arbitrary File Uploads

Can anyone point me to a good way to have multiple non-arbitrary file
uploads on Rails, possibly with a plugin? I came up with my own way
using a single generic file upload model and single table inheritance,
but I was wondering if there’s a better way.

By non-arbitrary I mean each file upload has it’s own purpose so I
must be able to access it individually and it should have it’s own
validation rules.

Thanks in advance