- disk_usage = Disk.query.filter(Disk.c.machine_id != machine_id).\
- join('machine').\
- filter_by(owner=owner).sum(Disk.c.size) or 0
+ disk_usage_query = Disk.query.filter(Disk.machine_id != machine_id).\
+ join('machine').filter_by(owner=owner)
+
+ disk_usage = sum([m.size for m in disk_usage_query]) or 0