[英]JPA Query to deleteById for a Composite Key declared using IdClass
[英]JPA removing query with IdClass issue
当我在JPA中使用Idclass用于具有复合键的实体时,我编写了一个remove方法,如:
private static void removeEmployee(Employee employee) {
EntityManagerFactory emf = Persistence
.createEntityManagerFactory("JPA_excer_3b");
EntityManager em = emf.createEntityManager();
try {
em.getTransaction().begin();
Employee anemployee = em.find(Employee.class, employee.getId());
em.remove(anemployee);
em.getTransaction().commit();
} catch (Exception e) {
logging.error("This error is added a removing a employee :"
+ " :" + e);
} finally {
// Close all the connections:
em.close();
emf.close();
}
}
我收到错误:
ERROR Logger:22 - This error is added a removing a employee :java.lang.IllegalArgumentException: Provided id of the wrong type for class be.leerstad.JPA.entities.Employee. Expected: class be.leerstad.JPA.entities.EmployeePK, got class java.lang.Integer
当我将代码更改为:
private static void removeEmployee(Employee employee) {
EntityManagerFactory emf = Persistence
.createEntityManagerFactory("JPA_excer_3b");
EntityManager em = emf.createEntityManager();
try {
**EmployeePK pk = new EmployeePK(employee.getId(),employee.getEmail());**
em.getTransaction().begin();
Employee anemployee = em.find(Employee.class, **pk**);
em.remove(anemployee);
em.getTransaction().commit();
} catch (Exception e) {
logging.error("This error is added a removing a employee :"
+ " :" + e);
} finally {
// Close all the connections:
em.close();
emf.close();
}
}
我没有得到任何错误,但我想知道这是否是正确的方法吗?
是的,这是正确的方法。 EntityManager.find()
方法需要实体的ID类的实例。 不是实体的一些随机属性。
请注意,错误不是由remove()
方法引起的,而是由find()
方法引起的。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.