Question

I have two tables:

1- Device :
2- User: has foreign key to device, relation is ManyToOne.

i have list of devices and the device can be deleted if it’s not assigned to a user
so i get all devices, and check if device is assigned to a user then set transient boolean property follows:

List <Device> devices = systemSettingsDao.getAllDevices();
            for (Device device : devices)
                device.setDeletable(!systemSettingsDao
                        .isDeviceUsedByUser(device.getId()));

i was wondering if there’s more elegant way to set the boolean property with querying (criteria is preferable) without making this for loop ?

Answer 1

Here’s how you could get all the deletable devices:

select distinct device from Device device where device.id not in (select u.device.id from User u)

You should be able to translate this with the Criteria API easily.