Hello!

I have an urgend problem and hope someone can help me.

That´s the initial situation:

interface X{
...
}

class abstract A{
...
}


class abstract B{
...
}


class C extends A implements X{
...
}

class D extends B implements X{
...
}

class E {

X element;
...

}


The class E has an X element (this could be C or D). The classes C und D inherit from absolut different classes (A und B) but implement the same interface (X).

Any idea, how this could be mapped?

A solution in which the superclasses (A und B) implement the interface is not relevant. Only C and D should implement the Interface.

Many thanks!!

wl

Can you include what you want your tables to look like?

It seems like you can have two tables: C and D

Just provide mappings for both C and D. The fact that they both implement the X interface does not interfere with the mapping since you are mapping "properties" of the classes, not the "behavior" that an interface adds to a class.

Hello!


First of all, thanks for your answer!

The problem is, that the class E (also a persistent class) should have a property from the interface type X (this could be C or D). So i must declare in the mapping for C and D that they implement the X-Interface.
I don´t know how i could declare this.

<class name="E">
....
<many-to-one name="element" entity-name="X">
</many-to-one>

<!-- The element could be C or D -->



</class>

<class name="C" extends="A">
....
</class>

<class name="D" extends="B">
....
</class>

Hope you can help me.

Thanks in advance.

wl

Now I　ｕｎｄｅｒｓｔａｎｄ　ｙｏｕｒ　ｉｓｓｕｅ．　　I haven't done this before, but there's a special mapping tag called a discriminator that handles polymorphic persistence. Try reading this section of the reference manual: http://www.hibernate.org/hib_docs/v3/reference/en/html_single/#mapping-declaration-discriminator


5.1.6. discriminator

The <discriminator> element is required for polymorphic persistence using the table-per-class-hierarchy mapping strategy and declares a discriminator column of the table. The discriminator column contains marker values that tell the persistence layer what subclass to instantiate for a particular row. A restricted set of types may be used: string, character, integer, byte, short, boolean, yes_no, true_false.