CODEWITHSUNDEEP
jpaeclipselink
user123435234234234
user123435234234234

Reputation: 13

Eclipselink + JPA generates ID column unexpectedly

Eclipselink generated a create table statement like so:

Create Table myTable (ID (255) not null, col1 (255), col2(255), col3(255) PK (ID, col1, col2)  



@Embeddable  
MyPK implements Serializable  
{  
    @OneToOne  
    @Id  
    String col1;  

    @OneToOne  
    @Id   
    String col2;    
...  
}  



@Entity  
MyClass implements Serializable  
{  
   @EmbeddedId  
   MyPK pk;  
   String col1;  
   String col2;  
   String col3;  
...  
}

How do I prevent the generation of the ID column in the Create Table statement? I ask because em.persist(MyClass) throws a constraint exception on ID being null. I expected that the @EmbeddedId would override this and prevent that field from being created.

EDIT
The table that I am trying to generate in code looks like so: 

fk - col1  
fk - col2
VarChar  - col3

Upvotes: 1

Views: 420

Answers (1)

Gordon Yorke
Gordon Yorke

Reputation: 1996

First issue is a String attribute can not be a OneToOne mappings. Second a OneToOne mapping can not be used within an EmbeddedId. Third you do not use the @Id annotation within an EmbeddedId as an Embeddable can not have identity.

The easiest way to do this is:

@Entity
@IdClass(MyPK.class)  
MyClass implements Serializable  
{  
   @OneToOne
   @Id
   TargetClass rel1;

   @OneToOne
   @Id
   SecondTargetClass rel2

   @Basic
   String col3;  
...  
}

MyPK implements Serializable  
{  
    String rel1;  

    String rel2;    
...  
}

If you really need an Embeddable for the pk class then replace the @ID annotation with @MapsId and add the EmbeddedId annotation back in MyClass and the Embeddable annotation back to MyPK

Upvotes: 2

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