'Emulate the _t property from tdb_sql: a dictionary of all
values that are or will be stored in the database, (not
including _defaults or unrequested properties on
partials)'

@property
def _t(self):

    ret = self._orig.copy()
    ret.update(self._dirties)
    for k in self._deletes:
        try:
            del ret[k]
        except KeyError:
            pass
    return ret
