There are lots of plugins available for upload files in ruby on rails.

file_column plugin:
attachment_fu
flex_image
upload_column
and many more

Accoding to  me, all these file are more useful for image uplaoding not other files like voice file, pdf and other.
So I made a defination which check following things and then upload a file on defined location.
1. File extension.
2. Mime [...]