java - JPQL 内部类型转换

Question

Item实体已扩展到另一个具有Vmp属性的Entity Amp。如何在 Jpql 中查询 Vmp。我可以在 Jpql 中进行转换吗？

我使用了 Jpql，但没有像这样进行转换。

select i from Stock i where i.stock >:s and i.department=:d and i.itemBatch.item.vmp=:vmp order by i.itemBatch.item.name

ItemBatch 具有 Item 类的属性，但我仅收回 Amp 实体，它扩展了 Item 类。只有Amp具有Vmp的属性。所以上面的 Jpql 给出了以下错误。

Caused by: java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager: 
Exception Description: Problem compiling [select i from Stock i where i.stock >:s and i.department=:d and i.itemBatch.item.vmp=:vmp order by i.itemBatch.item.name]. 
[85, 105] The state field path 'i.itemBatch.item.vmp' cannot be resolved to a valid type.

我可以像下面这样在 Jpql 中进行转换吗？还有其他解决方法吗？

select i from Stock i where i.stock >:s and i.department=:d and  Atm(i.itemBatch.item).vmp=:vmp order by i.itemBatch.item.name

Answer 1

我找到了方法，必须使用treat而不是cast。这是Jpql

jpql = "select i from Stock i join treat(i.itemBatch.item as Amp) amp where i.stock >:s and i.department=:d and amp.vmp=:vmp order by i.itemBatch.item.name";