How can I migrate attachment_fu out of the database?

I'm working on a Rails project that currently receives uploaded files using attachment_fu and stores files in the database. I'd like to move them to use the filesystem. The probl开发者_开发问答em is that there are currently several thousand uploaded files in the database, and we need to migrate them out. I can't seem to find anything to help with this; it seems the only migration anyone is posting tips for is filesystem -> S3. How would I go about migrating my files out of the database?

If you are ultimately attempting to serve these static files via S3/CloudFront to reduce load on your web/app servers one thing I may suggest is utilizing the new Custom Origin functionality of CloudFront which would allow you to keep your source files where they are. After being set up the process would basically be:

1. Your app tells the browser to retrieve the file from http://your-coudfront-host/path/to/file
2. The browser requests the file
3. If CloudFront has that file it returns it
4. If CloudFront does not have the file it retrieves it from your application and caches it for future requests (I believe up to 24 hours.)

This is what I am doing for product images that are dynamically generated on the fly in an application I am currently writing.

The upside of this is that you do not have to get into the overhead of constantly synchronizing data to S3 and if you decide to remove the whole setup you can still service your asset directly like nothing happened.