one-to-many

I have a problem. I'm learning JPA. I'm using embedded OpenEJB container in unit tests, but only working is @OneToMany(fetch=EAGER) . Otherwise is the collection allways null. I haven't found, how the lazy strategy works, how the container fills the data and in which circumstances triggers the container the loading action? I have read, that the action triggers when the getter is being called. But when I have the code: @OneToMany(fetch = LAZY, mappedBy="someField") private Set<AnotherEntities> entities = new Set<AnotherEntities>(); ... public Set<AnotherEntities> getEntities() { return entities

I'm trying to do a one-to-many relationship in Entity Framework where one of the many items is optionally designated as default. public class SomeEntity { public int Id { get; set; } public Item DefaultItem { get; set; } // Optional public ICollection<Item> Items { get; set; } } public class Item { public int Id { get; set; } public string ItemName { get; set; } public SomeEntity SomeEntity { get; set; } } The configuration for the one-to-many in fluent API seems pretty straightforward: HasMany(e => e.Items).WithRequired(i => i.SomeEntity).WillCascadeOnDelete(true); But the solution for

I have a composite key ContractServiceLocationPK made out of three id's ( contractId , locationId , serviceId ) of type long in an embeddable class. The class which uses this composite key, ContractServiceLocation , maps these ids, using @MapsId annotation, to their objects. Here's how it looks like (removed setters/getters and irrelevant properties): Contract @Entity @Table(name = "Contract") public class Contract implements Serializable { public Contract() { } @Id @GeneratedValue private long id; @OneToMany(mappedBy = "contract", cascade = CascadeType.ALL, fetch= FetchType.EAGER) Collection

I'm trying to design a pretty simple app and am getting myself a bit confused with Hibernate's definition of entity and value objects (as defined in Chapter 4 of Java Persistence with Hibernate). What I have is an app with customers, who can place orders (one to many relationship). Each of these orders has many order lines (also one to many). Now, I think that customers have identity (customer number) and so do orders (order numbers) so they are therefore entity objects? My confusion comes in with the order lines. An order line has quantity, product number and price. An order line can't exist

I have a many-to-many association in EF Code-First (as explained in this question), and I want to use a one-to-many to the same entity as well. The problem is EF does not produce the right database scheme. Code: public class A { public int Id { get; set; } public string Name { get; set; } public virtual ICollection<B> ObjectsOfB { get; set; } } public class B { public int Id { get; set; } public virtual A ObjectA { get; set; } public virtual ICollection<A> OtherObjectsOfA { get; set; } } When I remove the ObjectA property of class B the many-to-many association is generated correctly. When

I have a problem with one-to-many relationships. I have the following domain classes: public class Installation : Entity<Installation> { public virtual string Name { get; set; } public virtual IList<Institution> Institutions { get; set; } public Installation() { Institutions = new List<Institution>(); } } public class Institution : Entity { public virtual string Name { get; set; } public virtual string Address { get; set; } public virtual string City { get; set; } public virtual Installation Installation { get; set; } } I have made the Entity base class according to the following post . I have