Primary key not returned in OneToOne join fetch in eclipselink

Question

I have an issue join fetching in case of OneToOne relation in the same class. Example follows:

class Data {
 ...

 @Id
 @Column(name = "DATA_ID")
 Long id;

 @Column(name = "DATA_OWNER_ID")
 @ForeignKey(entityClass = Owner.class)
 Long ownerId;

 @Column(name = "DATA_RELATED_ID")
 @ForeignKey(entityClass = Data.class)
 Long relatedDataId;

 @OneToOne(fetch = FetchType.LAZY)
 @JoinColumn(name = "DATA_RELATED_ID", referencedColumnName = "DATA_ID", insertable = false, updatable = false)
Data relatedData;

}

I want to select data based on some conditions, while also fetching/initialising the "relatedData", all in one JPQL query:

SELECT owner.something1, data
FROM Data data
JOIN Owner owner on data.ownerId = owner.id
JOIN FETCH data.relatedData
WHERE data.something2 = :expectedSomething2

Executing that JPQL query throws an exception:

Query: ReadObjectQuery(name="relatedData" referenceClass=Data)|Exception:
javax.persistence.PersistenceException: Exception [EclipseLink-6044] (Eclipse Persistence Services - 2.6.2.v20151217-774c696): org.eclipse.persistence.exceptions.QueryException
Exception Description: The primary key read from the row [DatabaseRecord(
DATA_X => something
DATA_Y => something2
...
)] during the execution of the query was detected to be null.  Primary keys must not contain null.

Which is somewhat true, as there is no DATA_ID column listed. Changing JOIN FETCH to LEFT JOIN FETCH returns both owner.something1 and data , but the relatedData object is null (relatedDataId is not null).

I can see, that the id for relatedData is returned from DB, but eclipselink trims it in valueFromRowInternalWithJoin and trimRowForJoin methods.

Answer 1

The Id column name attribute value is the reason of this exception. Same issue found in eclipselink version 2.3.2 but it works fine in version 2.0.0 Try with this entry:

eclipselink.jpa.uppercase-column-names=true

OR Try with upper and lower case one by one which on will work for you.

@Id
@Column(name = "UUID")   // UUID - uppercase/lowercase one by one
Long id;

Answer 2

I've somehow resolved this issue, but haven't had the time to correctly identify the cause. Final (working) version differences are:

1. I could've forgotten to add get/set for relatedData
2. I have specified targetEntity = Data.class in @OneToOne
3. Fetch is now a LEFT JOIN FETCH and appears before JOIN Owner owner