[rules-users] Possible to check for null and empty string in same rule?

One of the checks that we are required to do on our data is that the data is not blank, meaning the value retrieved from the DB is not null and not "" (empty string) or '' (empty characer), etc.. Is there anyway to create a DSL entry to do this check regardless of the data type (Stirng, character, Date, etc.) that is returned? I have tried the obvious ({field} == null || {field} == "") but this only works for String types. I would really like to have just one DSL entry that would handle all cases. Thanks, Brian Enderle