Google App Engine - 删除JPQL查询和级联 [英] Google App Engine - DELETE JPQL Query and Cascading

问题描述

我注意到，在使用下面的JPQL查询时，PersistentUser的子项不会被删除。但是，如果我执行 entityManager.remove（object），则会删除子项。这是预期的吗？为什么下面的JPQL查询不会执行级联删除？

  @OneToMany（mappedBy =persistentUser，cascade = CascadeType .ALL）
私人收藏< PersistentLogin> persistentLogins; 
 
 ... 
 
 @Override 
 @Transactional 
 public final void removeUserTokens（final String username）{
 final Query query = entityManager .createQuery（
DELETE FROM PersistentUser p WHERE username =：username）; 
 query.setParameter（username，username）; 
 query.executeUpdate（）; 
} 
  

解决方案

删除操作不会级联。根据JPA 1.0规范：

lockquote

4.10批量更新和删除操作

（ ...）

删除操作仅适用于指定类的
实体和
的子类。 不会将
级联到相关实体。

I noticed that the children of PersistentUser are not deleted when using the JPQL query below. However, the children are deleted if I perform an entityManager.remove(object). Is this expected? Why doesn't the JPQL query below also perform a cascaded delete?

@OneToMany(mappedBy = "persistentUser", cascade = CascadeType.ALL)
private Collection<PersistentLogin> persistentLogins;

...

@Override
@Transactional
public final void removeUserTokens(final String username) {
    final Query query = entityManager.createQuery(
        "DELETE FROM PersistentUser p WHERE username = :username");
    query.setParameter("username", username);
    query.executeUpdate();
}

解决方案

This is expected, the JPQL delete operation does not cascade. From the JPA 1.0 specification:

4.10 Bulk Update and Delete Operations

(...)

A delete operation only applies to entities of the specified class and its subclasses. It does not cascade to related entities.

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