Java JPQL内部的铸造

项目实体已扩展到另一个属性为Vmp的实体Amp。如何在Jpql中查询Vmp。我可以在Jpql内部进行铸造吗

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，但我只收回Amp实体，它扩展了Item类。只有Amp具有Vmp属性。因此，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内部强制转换吗？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

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我找到了方法，只好用治疗代替石膏。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";