Permissions, "soft read failure" - wishful thinking?

Is there a way to set PG field-level read permissions so that a deny doesn't
cause the query to bomb, but the fields for which permission is denied to be
nullified?

In our web-based app, we have a request to implement granular permissions:
table/field level permissions. EG: userX can't read customers.socialsecurity in
any circumstance. We'd like to implement DB-level permissions; so far, we've
been using an ORM to manage CRUD permissions.

This is old hat, but our system has a large number of complex queries that
immediately break if *any* field permission fails. So, implementing this for
customers could be *very* painful....

Is that there is a way to let the query succeed, but nullify any fields where
read permissions fail? (crossing fingers) We'd be watching the PG logs to
identify problem queries in this case.