generate unique urls associated to a user each unique url is linked to an object and a user. The url usage can be tracked by clicks number. Each url has an expiration date.
Thanks to Ned Batchelder : http://stackoverflow.com/a/1360222
This become very handy when your models are actual files and you want to make them available for download with a minimal level of security.
A few parameters are needed:
UNIQUE_URL_OBJECT: the model class that the urls will correspond to
UNIQUE_EXP_DATE: the urls expiration date
UNIQUE_MAX_CLICS: the max clics allowed per url
unique/download_error.html : the download error page