Child entity with Secondary Table and Compound Key spread over two tables - jpa

Question

After much debate on choosing an approach for an internationalized database design I went with having two tables for each table that requires translation. I'm having some trouble with ORM in the following case.
So I have the following tables:
cat cat_t subcat subcat_t
------ ------- ---------- ------------
id (pk) cat_id(pk,fk) id(pk) subcat_id(pk,fk)
locale(pk) cat_id(fk) locale(pk)
name name
#Entity
#Table(name = "cat")
#SecondaryTable(name = "cat_t",
pkJoinColumns = #PrimaryKeyJoinColumn(name = "cat_id",
referencedColumnName = "id"))
#IdClass(TranslationKey.class)
public class Category {
#Id
private long id;
#Id
#Column(table = "cat_t")
private String locale;
#Column(table = "cat_t")
private String name;
#OneToMany(fetch = FetchType.LAZY)
private List<SubCategory> subCategories;
// getters and setters
}
#Entity
#Table(name = "subcat")
#SecondaryTable(name = "subcat_t",
pkJoinColumns = #PrimaryKeyJoinColumn(name = "subcat_id",
referencedColumnName = "id"))
#IdClass(TranslationKey.class)
public class SubCategory{
#Id
private long id;
#Id
#Column(table = "subcat_t")
private String locale;
#Column(table = "subcat_t")
private String name;
#Column(name = "cat_id")
private long categoryId;
// getters and setters
}
public class TranslationKey implements Serializable {
private long id;
private String locale;
// getters and setters
}
My goal is for subcategories to only pull back the subcategories for the locale of the parent. I think I have some options including, querying the subcategories separately and making the field transient or pull everything back (all subategories for all languages) and then just filter out the ones I want.
The issue I have had with #JoinColumn is that locale is part of the secondary table for both cat can subcat and so when I try the referencedColumn that may not be allowed since its not in the same table?. I'm using EclipseLink but I'm not really tied to a JPA Provider.
Any help/guidance is much appreciated

Answer 1

cat seems to have a one to many relationship with cat_t, since there can be many rows in cat_t for a single cat entry. This is not ideal to have in a single Entity, since it means you will have instances sharing data, and endless headaches if you make changes.
A better approach that makes updates possible is to map the cat and cat_t to separate Entities, where Cat has a collection of Cat_t?Local instances. The entity mapping to cat_t can use the local and its ManyToOne back pointer to Cat as its Id:
#Entity
#IdClass(TranslationKey.class)
public class Local {
#ID
private String locale;
#ID
#ManyToOne
private Cat cat;
}
public class TranslationKey{
string local;
long cat;
}