I'm newbie, Searched a lot for tutorials related to File upload, but
all are out-dated.
I'm want to implement simply, no Database, no Model, without any
plugin.
Just want to upload in Public Folder, and list out if any file is
saved.
Can anyone show me this simple code.
Just curious why you want to do this without using any database or models or gems?
At any rate, check out this tutorial below. It uses a model, but you can copy the code from the DataFile class to accomplish what you are trying to do.
By the way, that tutorial is the first result in Google when you search for “file upload rails” Google is usually a good place to start for questions like this.