java - 删除具有关系的实体

Question

我有下一个实体。 Car 与 Human 具有多对多关系。我在 Car 和 User

之间使用辅助类 Assign

@Entity
public class Car implements Serializable
{
   //...

   @LazyCollection(LazyCollectionOption.TRUE)
   @OneToMany(cascade = CascadeType.ALL, mappedBy = "car")
   private Set<Assign> cars = new HashSet<Assign>();
   //...
}  

@Entity
class Assign implements Serializable 
{
   //...

   @LazyCollection(LazyCollectionOption.FALSE)
   @ManyToOne
   @JoinColumn(name = "HUMAN_CAR", nullable = false)
   private Human human;

   @LazyCollection(LazyCollectionOption.FALSE)
   @ManyToOne
   @JoinColumn(name = "CAR_HUMAN", nullable = false)
   private Car car;
   //..

}  

@Entity
public class Human implements Serializable
{
    //...

   @LazyCollection(LazyCollectionOption.TRUE)
   @OneToMany(cascade = CascadeType.ALL, mappedBy = "human")
   private Set<Assign> cars = new HashSet<Assign>();  
   // ...  
}

现在我尝试删除容器内的汽车管理事务

   public void deleteCar(final long id)
   {      
      final Car car = entityManager.find(roleId, Car.class);
      entityManager.remove(car);  
   }  

但我明白了

Caused by: javax.persistence.EntityNotFoundException: deleted entity passed to persist: [com.dto.Assign#<null>]

Answer 1

在删除Car之前删除Assign-s

public void deleteCar(final long id)
{      
  final Car car = entityManager.find(roleId, Car.class);
  for(Assign assign : car.getAssigns()) {
     entityManager.remove(assign);
  }
  entityManager.remove(car);  
} 

您的 getter 可能有不同的名称，我看不到该代码。