使用Spring Boot和Hibernate保护单个实体免于级联删除

Question

I have a project that I'm working on in which I have a group and that group has a group-image (id and url). When I delete a particular group, I want it to delete its image entity from the MySql database as well.

But, the first group-image entity in the database is a url to a generic icon that I have placed there with an ID of one.

I understand that when I delete a group, the associated image entity gets deleted as I have the cascade type set to all.

This presents a problem when a group that uses the generic icon is deleted as it will then set the group_image_id to NULL causing an NPE.

My question is, is there a way to protect a single group-image entity from the effects of cascade delete?

Answer 1

I have never tried this, but one option to explore is customizing the delete statement that is used on the entity type that you want to prevent deletion where id=1. You can do this with the @SQLDelete annotation and include in the where-clause "and id <> 1" or something similar.

The default behavior (without specifying @SQLDelete) is to delete by ID.

I am suggesting that try something like:

@Table(name="mytable")
@SQLDelete("delete from mytable where id=? and id<>1")
public class MyEntity {
    ...
}