Hi can I persist a class that effectively like this,

I have a concrete class called GlobalRule,
which I want to change to an interface,

I have concrete classes that will then implement GlobalRule,
RuleA,
RuleB,
RuleC etc,

in our framework design we want to change GlobalRule which is currently a concrete class to an interface so that we create many types of rule objects and then persist,

is there a way in hibernate so I can then persist GlobalRule without getting the error cannot instantiate an abstract class or interface error that hibernate throws.

There are, in fact, many different ways to do that. This is a good thing if you like choice and a bad thing if you don't like your head exploding the first time you try to decide which way to do it. Read Chap 10 of the manual for the details. I recommend setting up a tiny testing project with classes like "BaseClass" and "JoinedSubClass" and "DiscriminatorSubClass" and test out each section of Chap 10 before trying to read the whole thing. It will keep spontaneous noggin combustion to a minimum.

For what it's worth, if your GlobalRule classes are all very similar, you probably want the approach in section 10.1.1. Table per class hierarchy. If they have a lot of different fields, then 10.1.2. Table per subclass is good. Those are the two main ones, and unless you have a pretty complex mix-in class hierarchy that you want to persist, one or the other should work for you.

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Eric

Helpful? Hit me with a credit!

Thanks a million I'll look into this?