[jboss-user] [EJB 3.0] - Lazy loading for OneToOne association (entities share the sa

[akovcic]

Hello,

I can't make one-to-one association lazy in case when entities share the same primary key. For the case when foreign key is held by one of the entities it works fine. Maybe I miss something. Here is the setup:

Entity A 
|
+---> Entity B (by FK)
|
+---> Entity C (shared PK)

Here is the code of Entities A, B, C

  | @Entity
  | @Table(name = "T_TEST_A")
  | public class EntityA implements Serializable {
  | 
  |   private int id;
  |   private String description;
  |   private EntityB entityB;
  |   private EntityC entityC;
  | 
  |   public EntityA() {
  |   }
  | 
  |   /**
  |    * @return Returns the id.
  |    */
  |   @Id
  |   @Column(name = "ID")
  |   public int getId() {
  |     return id;
  |   }
  | 
  |   /**
  |    * @param id The id to set.
  |    */
  |   public void setId(int id) {
  |     this.id = id;
  |   }
  | 
  |   /**
  |    * @return Returns the description.
  |    */
  |   @Column(name = "DESCRIPTION")
  |   public String getDescription() {
  |     return description;
  |   }
  | 
  |   /**
  |    * @param description The description to set.
  |    */
  |   public void setDescription(String description) {
  |     this.description = description;
  |   }
  | 
  |   /**
  |    * @return Returns the entityB.
  |    */
  |   @OneToOne(fetch = FetchType.LAZY)
  |   @JoinColumn(name = "B_ID")
  |   public EntityB getEntityB() {
  |     return entityB;
  |   }
  | 
  |   /**
  |    * @param entityB The entityB to set.
  |    */
  |   public void setEntityB(EntityB entityB) {
  |     this.entityB = entityB;
  |   }
  | 
  |   /**
  |    * @return Returns the entityC.
  |    */
  |   @OneToOne(fetch = FetchType.LAZY)
  |   @PrimaryKeyJoinColumn
  |   public EntityC getEntityC() {
  |     return entityC;
  |   }
  | 
  |   /**
  |    * @param entityC The entityC to set.
  |    */
  |   public void setEntityC(EntityC entityC) {
  |     this.entityC = entityC;
  |   }
  | 
  |   @Override
  |   public String toString() {
  |     return "EntityA[id = " + id + ", description = " + description + "]";
  |   }
  | 
  | }
  | 
  | 


  | @Entity
  | @Table(name = "T_TEST_B")
  | public class EntityB {
  | 
  |   private int id;
  |   private String description;
  | 
  |   public EntityB() {
  |   }
  | 
  |   /**
  |    * @return Returns the id.
  |    */
  |   @Id
  |   @Column(name = "ID")
  |   public int getId() {
  |     return id;
  |   }
  | 
  |   /**
  |    * @param id The id to set.
  |    */
  |   public void setId(int id) {
  |     this.id = id;
  |   }
  | 
  |   /**
  |    * @return Returns the description.
  |    */
  |   @Column(name = "DESCRIPTION")
  |   public String getDescription() {
  |     return description;
  |   }
  | 
  |   /**
  |    * @param description The description to set.
  |    */
  |   public void setDescription(String description) {
  |     this.description = description;
  |   }
  |   
  |   @Override
  |   public String toString() {
  |     return "EntityB[id = " + id + ", description = " + description + "]";
  |   }
  | 
  | }
  | 


  | @Entity
  | @Table(name = "T_TEST_C")
  | public class EntityC {
  | 
  |   private int id;
  |   private String description;
  | 
  |   public EntityC() {
  |   }
  | 
  |   /**
  |    * @return Returns the id.
  |    */
  |   @Id
  |   @Column(name = "ID")
  |   public int getId() {
  |     return id;
  |   }
  | 
  |   /**
  |    * @param id The id to set.
  |    */
  |   public void setId(int id) {
  |     this.id = id;
  |   }
  | 
  |   /**
  |    * @return Returns the description.
  |    */
  |   @Column(name = "DESCRIPTION")
  |   public String getDescription() {
  |     return description;
  |   }
  | 
  |   /**
  |    * @param description The description to set.
  |    */
  |   public void setDescription(String description) {
  |     this.description = description;
  |   }
  | 
  |   @Override
  |   public String toString() {
  |     return "EntityC[id = " + id + ", description = " + description + "]";
  |   }
  |   
  | }
  | 

Extract from the test case that fails:


  |   public void testExecutionFormatLookup() throws Exception {
  |     EntityManager em = getEntityManager();
  |     TransactionManager tm = getTransactionManger();
  | 
  |     try {
  |       tm.begin();
  | 
  |       EntityA ea = em.find(EntityA.class, new Integer(1));
  |       assertNotNull(ea);
  |       
  |       assertFalse("Entity B is initalized", Hibernate.isInitialized(ea.getEntityB()));
  |       assertFalse("Entity C is initalized", Hibernate.isInitialized(ea.getEntityC())); // FAILS!!!
  | 
  |       log.info("Selected entity: " + ea);
  |     }
  |     finally {
  |       tm.commit();
  |     }
  |   }
  | 

I see two selects executed on find(). One loads entity A, and another laods and initializes association to entity C:


  | Hibernate: select entitya0_.ID as ID88_0_, entitya0_.B_ID as B3_88_0_, entitya0_.DESCRIPTION as DESCRIPT2_88_0_ from T_TEST_A entitya0_ where entitya0_.ID=?
  | Hibernate: select entityc0_.ID as ID90_0_, entityc0_.DESCRIPTION as DESCRIPT2_90_0_ from T_TEST_C entityc0_ where entityc0_.ID=?
  | 

The structure of tables is rather simple:
T_TEST_A: ID (PK), DESCRIPTION, B_ID (FK to T_TEST_B.ID)
T_TEST_B: ID (PK), DESCRIPTION
T_TEST_C: ID (PK), DESCRIPTION

Using jboss embeddable when junit testing:

  | 12:33:38,461 INFO  [Version] Hibernate EntityManager 3.2.0.CR1
  | 12:33:38,476 INFO  [Version] Hibernate Annotations 3.2.0.CR1
  | 12:33:38,492 INFO  [Environment] Hibernate 3.2 cr2
  | 12:33:38,492 INFO  [Environment] hibernate.properties not found
  | 12:33:38,507 INFO  [Environment] Bytecode provider name : cglib
  | 12:33:38,539 INFO  [Environment] using JDK 1.4 java.sql.Timestamp handling
  | ....
  | 

What to do to make association to entity C lazy loadable?
Tahnks for help.

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