NH3 and above allow to correct save entities in case of uni-directional one-to-many mapping without annoying save null–save–update cycle, if you set both not-null=”true” on <key> and inverse=”false” on <one-to-many> FluentNHibernate code snippet for that: public class MasterMap : ClassMap<Master> { public MasterMap() { Id(x => x.MasterId); Map(x => x.Name); HasMany(x => x.Details) .Not.Inverse() //these … Read more
It’s a bug in Hibernate. Surprisingly, it’s not reported yet, feel free to report it. Operations against non-initialized lazy collections are queued in order to execute them after collection is initialized, and Hibernate doesn’t handle the situation when these operations conflict with the data from the database. Usually it’s not a problem, because this queue … Read more
Consider the situation where the owned entity type can also be owned by another parent entity type. Do you put foreign key references in the owned table to both parent tables? What if you have three parent types? It just doesn’t scale to large designs. A join-table decouples the join, so that the owned table … Read more
Suppose you have an Order and an OrderLine. You can choose to have a unidirectional OneToMany between Order and OrderLine (Order would have a collection of OrderLines). Or you can choose to have a ManyToOne association between OrderLine and Order (OrderLine would have a reference to its Order). Or you can choose to have both, … Read more
the problem is this: post = Post(body=form.body.data, timestamp=datetime.utcnow(), thread=thread.id, author=g.user.id) you want to work with ORM objects, not primary key columns: post = Post(body=form.body.data, timestamp=datetime.utcnow(), thread=thread, author=g.user) the error means that an integer is being interpreted as an ORM object.
The solution is to do exactly what the exception message tells you: Caused by: org.hibernate.ObjectDeletedException: deleted object would be re-saved by cascade (remove deleted object from associations) Remove the deleted object from an associations (sets, lists, or maps) that it is in. In particular, i suspect, from PlayList.PlaylistadMaps. It’s not enough to just delete the … Read more
I am not really sure about your question (the meaning of “empty table” etc, or how mappedBy and JoinColumn were not working). I think you were trying to do a bi-directional relationships. First, you need to decide which side “owns” the relationship. Hibernate is going to setup the relationship base on that side. For example, … Read more
As Matthieu says, the only case where you wouldn’t want to set inverse = true is where it does not make sense for the child to be responsible for updating itself, such as in the case where the child has no knowledge of its parent. Lets try a real world, and not at all contrived … Read more
The Manning book Java Persistence with Hibernate has an example outlining how to do this in Section 7.2. Fortunately, even if you don’t own the book, you can see a source code example of this by downloading the JPA version of the Caveat Emptor sample project (direct link here) and examining the classes Category and … Read more
You have to set the associatedEmployee on the Vehicle before persisting the Employee. Employee newEmployee = new Employee(“matt”); vehicle1.setAssociatedEmployee(newEmployee); vehicles.add(vehicle1); newEmployee.setVehicles(vehicles); Employee savedEmployee = employeeDao.persistOrMerge(newEmployee);