Just talking about simple id, even if we allow the column to be nullable (if the DB even allows that), I don't think Hibernate allows null to be a valid id value. Because null means I don't know or not applicable. I think in the past we argued the same for attributes of a composite id, like you said, if one of the element can be nul, why is it in the id property in the first place.
As for whether there is a strong implementation detail reason to not allow it, I don't know but I assume the null checking assuming "not an id" is pretty much all over the place. Emmanuel On 11 Dec 2019, at 3:37, Gail Badner wrote: > Currently, there is no way to load an entity that exists in the > database > with a composite ID, if one of the composite ID columns is null. > > This behavior is due to this code in ComponentType#hydrate: > https://github.com/hibernate/hibernate-orm/blob/master/hibernate-core/src/main/java/org/hibernate/type/ComponentType.java#L671-L675 > > Basically, if any field/property in a composite ID is null, Hibernate > assumes the entire ID is null. An entity cannot have a null ID, so it > returns null for the entity result. > > I believe that Hibernate does allow a primary key column to be > nullable. > > TBH, it seems strange to have a property in a composite ID that can be > null. If it can be null, it seems that the property could be removed > from > the composite key. > > I don't see anything in the spec about a requirement that all > composite ID > fields/properties must be non-null. Am I missing something? > > The code I referenced above is 13 years old. Does anyone have insight > into > why Hibernate does this? > > Thanks, > Gail > _______________________________________________ > hibernate-dev mailing list > hibernate-dev@lists.jboss.org > https://lists.jboss.org/mailman/listinfo/hibernate-dev _______________________________________________ hibernate-dev mailing list hibernate-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/hibernate-dev
