About ManyToOne

manual

JPA Entity Fields

Explains how to define and use primary keys in JPA, including composite and embedded primary keys.... See JavaDoc Reference Page... , ManyToOne javax.persistence.ManyToOne JPA annotation Defines a single-valued association to ...

 
api-jpa

JPA Annotations for Relationships

Reference (JavaDoc) of JPA 2 relationship annotations, including @ManyToMany, @ManyToOne, @OneToMany, @OneToOne, @OrderBy and @MapKey.... javax.persistence.ManyToMany javax.persistence.ManyToOne javax.persistence.OneToMany ...

 
forum_thread

LAZY @ManyToOne field functions as EAGER

In the code example below (also attached) I would like to understand why I am able to print to console a lazy @ManyToOne field after the entity manager closes. There is a switch DO_VIEW_BEFORE_CLOSE, and when it is true the fields are accessed and output before the finding entity manager closes and as expected both a LAZY @ManyToOne field and an EAGER @ManyToOne field are viewable: b.cLazy:{C}[2]"cLazy"
 b.cEager:{C}[3]"cEager" ... to understand why I am able to print to console a lazy @ManyToOne field after the entity manager closes. There is a ... finding entity manager closes and as expected both a LAZY @ManyToOne field and an EAGER @ManyToOne field are viewable: b.cLazy:{C}[2]"cLazy"
 ...

 
forum_thread

Broken @ManyToOne reference

Hi, I have objects of type A belonging to objects of type B, defined as follows: @MappedSuperclass public abstract class A {   @Id   @ManyToOne(fetch = FetchType.EAGER, cascade=CascadeType.ALL, optional=false)   private B b;   @Id   @Column(length = 36)   private String stringId; } @MappedSuperclass public abstract class B {   @Id   private String name; } ... class A { @ Id @ ManyToOne ( fetch = FetchType . EAGER , cascade ... . Id ; import javax. persistence . ManyToOne ; import javax. persistence . MappedSuperclass ; ...

 
forum_thread

ObjectDB Explorer don't show ManyToOne relations

Hello support. we have a problem with the ObjectDB Explorer and @ManyToOne relations. We persist the entity FolderImpl that has an attribute of type ModelElement. If we use an interface for the attribute then the ObjectDB Explorer shows NULL for the attribute although our unit test checks that the attribute is not NULL in the database. @Entity public class ModelElementImpl implements ModelElement { ... } @Entity public class FolderImpl { ... we have a problem with the ObjectDB Explorer and @ManyToOne relations. We persist the entity FolderImpl that has an ... public class FolderImpl { @ ManyToOne ( targetEntity = ModelElementImpl. class , ...

 
api-jpa

javax.persistence.ManyToOne

Defines a single-valued association to another entity class that has many-to-one multiplicity.(Annotation of JPA)

 
forum_thread

Should derived fields of an EmbeddedId be manually maintained by app code?

If I have an Entity which has a primary key which is derived and I am implementing it using @EmbeddedId, am I responsible for maintaining the derived fields of the @EmbeddedId? I could not find anything in the JPA 2.0 spec http://download.oracle.com/auth/otn-pub/jcp/persistence-2.0-fr-oth-JSpec/persistence-2_0-final-spec.pdf?e=1317047713&h=54831c176e81a244a4c309e13eba0b27 which tells me what to expect. ... FetchType ; import javax. persistence . ManyToOne ; import javax. persistence . MapsId ; ... public ECompoundKeyMapItemId id ;   @ ManyToOne ( fetch = FetchType . LAZY ) @ ...

 
forum_thread

find() cost unreasonable time!

Hi, I make a full binary tree of 4095 node, I check the first 9 node, but the root cost 24 seconds, why? Result: ... IDENTITY ) private int id ; @ ManyToOne @ JoinColumn ( name = "parent" ) ... JoinColumn ; import javax. persistence . ManyToOne ; import javax. persistence . OneToMany ; ...

 
forum_thread

Level 2 cache not hit in @ManyToOne

Hi! I have 2 entities: User and Item, both @Cacheable. Item has @ManyToOne private User user. Level 2 JPA cache is activated and it works ok for find by id (tested by changing data in explorer and reading in my app). Problem 1: find by id on Item it's good, it hits the cache, but not for its field "user". "user" is loaded each time from the DB (tested by changing data in explorer and reading in my app). "user" should also be taken from L2 cache, shouldn't it? Otherwise...it's a huge performance hit. ... have 2 entities: User and Item, both @Cacheable. Item has @ManyToOne private User user. Level 2 JPA cache is activated and it works ok for ...

 
forum_thread

EntityManager.refresh takes a long time

EntityManager.refresh takes a long time for entity object Person in this code: ... ( ) ;   @ ManyToOne private City city ; @ OneToOne ( ... ( ) ;   @ ManyToOne ( cascade = CascadeType . REFRESH ) ... ( ) ;   @ ManyToOne private PersonLevel level ;</ span > ...