@CreatedDate doesn't work on one-to-many relationship

[livanov]

A reproducible example here.

When we save the Aggregate Root, the @CreatedDate annotated field is correctly set and saved on the aggregate root and on the one-to-one entity relationship. However, it fails to assign it on the one-to-many entity relationship.

[schauder]

Auditing columns are currently by design only supported for the aggregate root, since based on DDD there really is only one life cycle: that of the aggregate.

Supporting auditing columns on inner entities of an aggregate would also be difficult since there really isn't a easy way of telling if those are new or modified without accessing the database for this.

Leaving this open in order to have a short team discussion about it.

[livanov]

Thanks for the prompt reply!

Auditing columns are currently by design only supported for the aggregate root, since based on DDD there really is only one life cycle: that of the aggregate.

I was also thinking that this could be why it is not supported. However, I think there is a valid business requirement that we'd like to see who created what within the aggregate - in my case - who changed the address. When I think about it now, I'd like to differentiate between who touched the Address and who touched the Person details, whereas even if inner entities' auditing was supported, I guess that the aggregate would still be updated.

Supporting auditing columns on inner entities of an aggregate would also be difficult since there really isn't a easy way of telling if those are new or modified without accessing the database for this.

I guess that the reason it works for the one-to-one relationship is some form of a side effect and not by design?

For the sake of anyone else looking of a workaround to that. I've implemented a custom BeforeConvertCallback<Object> that runs after org.springframework.data.relational.auditing.RelationalAuditingCallback and traverses the object with reflection looking for nested entities that "need" auditing. I am not sure how I can disable the org.springframework.data.relational.auditing.RelationalAuditingCallback and completely replace it.

[schauder]

I guess that the reason it works for the one-to-one relationship is some form of a side effect and not by design?

Strictly speaking it shouldn't work. Making it work could be considered a mistake. Although probably many wouldn't like me changing that now ...

[schauder]

We discussed this internally.

TL;DR: We'll leave it as it is.

If we support auditing annotations on inner entities they really should get the same value, the aggregate root.
This is ok for single references (embedded or not) to keep the auditing data somewhat seperate.
But for multivalued references (Set, List, Map) this would be quite useless.
So we keep it as it is: supported for single references but not for multivalued ones.

For the sake of anyone else looking of a workaround to that. I've implemented a custom BeforeConvertCallback that runs after org.springframework.data.relational.auditing.RelationalAuditingCallback and traverses the object with reflection looking for nested entities that "need" auditing.

You might find it helpful to use the JdbcMappingContext and its methods providing PersistentEntity and PersistentPropertyPath.

I am not sure how I can disable the org.springframework.data.relational.auditing.RelationalAuditingCallback and completely replace it.

Just don't enable auditing.