Hey,

Can anyone shed some light on how to use business logic Properties in a HQL Query.

Example



The first two properties are simply table field lookups however the State Property is not mapped in the .hbm file it is instead a container for derived logic. Depending on the first 2 numbers of the PlateNumber determines the state that it comes from. (forgive the bad example, state should be stored on create)

What I want to achieve is to be able to use the State Property in a HQL Query for example.



NHibernate doesn't seem to like this as State is not a mapped attribute. I can understand why this is the case as this can not be converted in to a SQL query of any type but would be might useful in attempting to better centralize business logic in model objects.

Can someone please advise?

Thanks, Adam

You could map State using <property formula="yourformula"/>, moving the derivation of its value into the Hibernate layer. This would make it accessible from HQL.

Thanks for the reply.

This could solve the problem I guess however I want to keep the business logic in the Business Tier and out of the Data Tier.

Ideally NHibernate would be able to post process business rules after queries have been executed. This presumably would cause a problem for aggregated queries.

Maybe I ask too much :(

Have you tried using a Custom UserType.
I am not sure how do you want to use it in a HQL query when it is not mapped to a table column.