How to delete a ManyToMany item using JPQL?

Question

I have two models, say:

BlogPost(title, message)
Tags(name)

Both have a ManyToMany relationship defined.

Using JPQL, I delete a list of BlogPost with this query:

DELETE FROM BlogPost b WHERE b IN :list

(:list is a List from a previous SELECT requet).

Doing so, I have a ConstraintViolationException because of the relation between BlogPost and Tags .

Is there a way to delete the relation without deleting the Tags using JPQL?

Thanks for your help!

Answer 1

You have to remove the association first, before you delete the entity.

Answer 2

JPA create a table BlogPost_Tags which stores ID of BlogPost and Tags.

So when you try to delete a BlogPost, the constraint on the BlogPost_Tags failed.

You need to delete the relation before delete the Post, and there is no easy way in JPQL, you have to use the EntityManager.

Answer 3

I'll answer myself with the solution I came up. I'm not sure it's the best one, but at least, it works.

Since you want to bulk delete something that have a ManyToMany related items, you first have to delete the relation (in the join table), or do a loop and for each item, delete manually (insane and too much heavy).

So, since JPQL does not allow to do it, a possible way is to make a native SQL query for deleting the id you want in the related table, and then, do the bulk delete.