filterstr = ''.join(['(objectClass=%s)' % cls for cls in self.model.object_classes])
sql, params = self.where.as_sql()
filterstr += sql
filterstr = '(&%s)' % filterstr
try:
filterstr = ''.join(['(objectClass=%s)' % cls for cls in self.model.object_classes])
sql, params = self.where.as_sql()
filterstr += sql
filterstr = '(&%s)' % filterstr
try: