Java QueryDSL投影和空值
鉴于此查询:Java QueryDSL投影和空值,java,jpa,querydsl,Java,Jpa,Querydsl,鉴于此查询: final List list = new JPAQuery(entityManager).from(qdevice).leftJoin(qdevice.parentDevice) .list(Projections.bean(Device.class, qdevice.id, qdevice.parentDevice)); (parentDevice是设备的类型) 问题是,查询仅在parentDevice不为null时返回设备。为什么?如何找回价值?如果我从投影中取出qdevi
final List list =
new JPAQuery(entityManager).from(qdevice).leftJoin(qdevice.parentDevice)
.list(Projections.bean(Device.class, qdevice.id, qdevice.parentDevice));
(parentDevice是设备的类型)
问题是,查询仅在parentDevice不为null时返回设备。为什么?如何找回价值?如果我从投影中取出qdevice.parentDevice,结果会很好
QueryDsl版本是3.2.0,你能试试吗
QDevice device = QDevice.device;
QDevice parentDevice = new QDevice("parentDevice");
List<Device> list = new JPAQuery(entityManager)
.from(device)
.leftJoin(device.parentDevice, parentDevice)
.list(Projections.bean(Device.class, device.id, parentDevice));
QDevice device=QDevice.device;
QDevice parentDevice=新的QDevice(“parentDevice”);
列表=新的JPAQuery(entityManager)
.来自(设备)
.leftJoin(device.parentDevice,parentDevice)
.list(Projections.bean(Device.class、Device.id、parentDevice));
list
中对qdevice.parentDevice
的引用可能被视为内部联接,因为它与左联接没有关联