[NHibernate 1.0.2]

Hello,
In my entities, I have some properties which are actually formulas, such as counting all orders for a Person entity. However, I want these calculated properties to be calculated only on "special request", not every time I read the person entity from the database.

What is the best approach to do this? As far as I can see, there is no "lazy=true" attribute for properties.

Thanks for any help,
Urs

Your property can just calculate the value and store it in a private variable (if you want to "cache" the result)

Lazy is specified for your persistent classes and collections, not calculated values.

If you want to do a calculation lazily, then you put the code in the property accessor and it won't be calc'ed until the calling code uses your property.

.. so in your case for Orders you might want the Orders property of a person to be lazy (which makes sense). Then your property would look like:

even better, though... would be to create a custom HQL query something like "COUNT (*) FROM Orders o WHERE o.Person = p"
(my HQL might be off a tad)

But this way you avoid querying for ALL orders just to get the count.