currently there is <subclass>, but no <superclass>?
in table-per-class-hierarchy model we can define subclass inside parent
class with different discriminator-values, but it's more nature in OO design
that 'extend' a class, that means parent class do not need to know how many
subclasses have been added.
for example, I have an order table,and I use a 'type' discriminator column
to indicate different kind of orders, such as 'normal order','discount
order', and they may have differents in calculating price.
So ,currently when a new order type was introduced, I need to find the
origional hbm file and add a new "<subclass>" tag. If the code already been
froze (may publish as a jar ), things will be more trouble to extend
existing class.
I think if we have a new tag to hbm file, life will be easier:
<class name="Order"
table="parent"
discriminator-value="0">
<id name="id">.....</id>
<discriminator column="type" type="int"/>
<property ...../>
...
</class>
...
<class name="ChristmasDiscountOrder"
table="order">
<id name="id">.....</id>
<superclass name="Order" discriminator-value="15">
</class>
Any comments? maybe this function already there but I can't find it out.
Xiaogang Cao
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