Storing binary files like images in the database can quickly become cumbersome. There was a time when we were storing user uploads like PDF's and such in the DB but it became unmanageable. We quickly moved it all over to S3 and made Paperclip store and retrieve the files there (encrypting the files before saving them to S3, and sending them over SSL since the files were potentially sensitive) and it made things much saner.
I'd say best bet for you is to use S3. Since
- On heroku you have a limited
database size (depending on your
plan) and could quickly run out if
you're storing binaries there.
- You can't dynamically save new files
to the filesystem on heroku, and
- S3 is cheap as hell (and free for
most casual use) to store and
retrieve files.
EDIT based on your comment:
Ok I mis-understood the question. Either store the image path in the database or have the image stored with such a path & naming convention that the code itself can figure out where to get the image (which is what paperclip does). Both ways are acceptable. NOTE that SASS is not truly dynamic, you can't pull paths from the database and make the sass change on-the-fly. I've run into a similar situation and the solution was to make the CSS point to a background-image that was in fact a route in the application. In our instance we were able to change the image displayed based on the subdomain or domain of the incoming user, but you could just as easily display that image based on a session cookie that gets set before the views are rendered.
While SASS is compiled, after it's been generated it is static. The syntax, and 'dynamic' nature of it are just to make writing CSS easier.