Question

I have:

static class Db4o...

and:

class Db4oBase... // which uses Db4o class

where I can:

class Customer : Db4oBase
{
    public Customer(string name)
    {
    }
}

so that I can:

Customer customer = new Customer("Acbel Polytech Philippines");

customer.store();  //something like that

It worked, until sometime in my development, the code below suddenly bugged down:

class Db4o
{
    .
    .
    .
    public static IObjectSet Retrieve(object obj)
    {
        IObjectSet objectSet = null;

        objectSet = container.Ext().QueryByExample(obj); // This part of the code
                                                         // throws a unsupported
                                                         // class hierarchy.

        return objectSet;
    }
}

The QueryByExample instruction throws an unsupported class hierarchy. Does anybody know what should I do?

Answer 1

It happened when you:

1. Code a class and then run the program.
2. Later you modify the code and add/change the parent class (changing the hierarchy)
3. Finally you run again and … CRASSHHH.

yes, Hierarchy (inheritance) is supported but change it is not so simple to apply on existent file.