休眠删除，侵犯儿童

Question

I am yet again stuck with trying to delete data with Hibernate..

I am at point where I am starting to just stack annotation, hoping something would work... so far nothing has.

I need to delete old calculation when starting new for same time period.

I have the following query

@Modifying
@QueryHints(value = @QueryHint(name = HINT_FETCH_SIZE, value = "10"))
@Query(value = "DELETE FROM Group a WHERE a.c_date BETWEEN :dateA AND :dateB")
void deleteOld(@Param("dateA") LocalDate dateA, @Param("dateB") LocalDate dateB);

which uses entity Group, which has (on top of normal String, LocalDate and long types) attribute

    @OneToMany(cascade=CascadeType.ALL, mappedBy = "owner", orphanRemoval = true)
    @JsonManagedReference
    @OnDelete(action = OnDeleteAction.CASCADE)
    private List<Instrument> instruments = new ArrayList<>();

But I still get violated - child record found every time I try to run delete method.

I keep finding more and more annotations like this, from threads where people have the same kind of problems, but I would love to understand why is this a problem. From what I read Cascade and orphanRemoval should be all I need, but it sure does not seem to be.

Hibernate: 5.2.17.Final

Please help me to understand, why is this happening ?

Answer 1

The @OnDelete will delete records using a ON DELETE rule on the database, when using Hibernate to generate the schema. If you manage your own schema this will have no effect.

The @QueryHints you have specified doesn't really make sense here, for an DELETE query that is. Nothing will be fetched.

The fact that you are using an @Query basically bypasses the configuration in the @OneToMany , simply due to the fact that you write a query and apparently know what you are doing. So the mapping isn't taken into account.

If you want to delete the childs as then you have 3 options:

1. Add an additional query and first remove the childs, then the parents
2. Add an ON DELETE rule to your database, to automatically remove the childs
3. Retrieve the Group and remove using EntityManager.remove which will take the @OneToMany mappings into account as now Hibernate needs to manage the dependencies between the entities.