Using Map<ClassB, ClassC> in JPA entities

[Chris Ward]

Hi all,

Does anyone out there have experience of using Map in JPA entities but
with a third class as the Key?

I have no problem in using the "standard" Map scenario - where the key
field is an attribute of the value object.

e.g.

@Entity
public class Department {
...

@OneToMany(fetch = EAGER)
@MapKey(name = "name")
private Map<String, Employee> employees = new HashMap<String,
Employee>();

...
}

Where the String (name) value is an attribute of the Employee class.



What I want to do is ...

@Entity
public class ClassA {
...

@OneToMany()
private Map<ClassB, ClassC> lookup = new HashMap<ClassB, ClassC>();

...
}

Where ClassB is NOT an attribute of ClassC.

Is there some funky form of the @MapKey annotation that I can use?

Many thanks for any replies on this.

Chris