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Hibernate version: 3.0.5

Mapping documents:

<hibernate-mapping>
<class name="com.farbeyond.ejb.research.model.OrderDetail"
table="OrderDetails"
...

<property name="totalBruto"
type="double"
formula="Quantity * UnitPrice"
update="false"
insert="false"/>
...
</class>
</hibernate-mapping>


Name and version of the database you are using: SQL Server 7.0

Hi all,

I need to order records by computed column, in this case the column is 'totalBruto' which is computed using Quantity * UnitPrice formula. To order records I use the following criteria :

...
criteria.addOrder(Order.asc("totalBruto"));
...

So far so good.

The problem is when user changes the field Quantity or UnitPrice I also want to recompute the totalBruto field right away and present it to user instantly. So I have to code the formula somewhere else in the OrderDetails class. I think from maintenance point of view this is cumbersome & error-prone approach because I have to maintain the formula in hibernate mapping & OrderDetails class.

I try to remove the totalBruto setter method and instead of writing the following totalBruto getter :

public double getTotalBruto()
{
return totalBruto;
}

I write the following totalBruto getter which directly returns the formula :

public double getTotalBruto()
{
return quantity * unitPrice;
}

I also remove the property elements of totalBruto field in the hibernate mapping.

The latter approach seems much easier to maintain since I only have to maintain the formula in the getTotalBruto method. But then I won't be able to order records by totalBruto field.

Is there any solutions for this or am I missing something ?

Any help would be greatly appreciated.


Regards,


Setya

I suggest removing the 'totalBruto' mapping from H mapping and have formula in one place: gettter method of the class

public double getTotalBruto() {
return quantity * unitPrice;
}

And for sorting, simply do it in the code: just implement interface Comparable on the class or provide custom Comparator to the Collections.sort method.

That's not going to work if you need to fetch paged results with .setFirstResult() / .setMaxResults().

My first thoughts were to try a custom UserType or by treating a TotalBruto class as a mapped component. I haven't explored this any deeper though to see if this is even possible. Certainly the mapping part isn't hard, but getting the order correct seems non-trivial.

My other thought is that for this specific case it probably doesn't matter. What are the chances that the definition of a totalBruto is ever going to change? From the description given it seems highly unlikely and not really a maintenance crisis if it does.

Thanks for your responses,

The formula I presented above is just a simple formula to describe my point. Actually in the real world I have a lot more complex formulas which are computed from a lot of fields in the class. My temporary solution now is to use the later approach and not give the user an option to order by the total bruto, but I don't like this solution since it will reduce the user-friendliness of my applications.

Any solutions are welcome.

Regards,

Setya