How to replace a @JoinColumn with a hardcoded value?

Question

For more context, please see my other question.

I want to join my Employee entity class to Code entity class but the Code PK is composite (

Answer 1

This should work?

@JoinColumn(name = "EMP_TYPE_CODE", referencedColumnName = "CODE")
@Where(clause = "domain = 'EMP_TYPE'")
@ManyToOne(optional = false)
private Code sharedStatute;

Answer 2

Note: Apparantly this solution is OpenJPA only.

There is a way to do this with javax.persistence annotations only:

@JoinColumns({
    @JoinColumn(name = "EMP_TYPE_CODE", referencedColumnName = "CODE"),
    @JoinColumn(name = "CODE_TABLE_NAME.DOMAIN", referencedColumnName = "'EMP_TYPE'")})
@ManyToOne(optional = false)
private Code sharedStatute;

Note the single quotes in the referencedColumnName, this is the String value you are looking for.

There is a downside however, when you have multiple Code objects in your entity, the join on DOMAIN will be done only once in jpa, giving bad results. At the moment I circumvent this by making those field load lazily, but that's not ideal.

More information here.