Is it possible to bind a scalar query result to a property in nhibernate?

Question

I have an entity which has a property that does not get its value from the entity's table. But it could be calculated by a query if it is possible.

To clarify, I have an entity of an Entry and I want to check if the current user voted it or not. So for that reason I thought that I could add a property like "IsCurrentUserVoted" to the Entry entity. And if it is possible to bind its value from a query like "select count(*) from vote where userId = :currentUser".

I wonder if nhibernate supports this kind of a feature or it is the only way to join the vote and entry tables? If it does not, what would your solution be in that case.

Thanks in advance.

Answer 1

Yes, I think you can do that with the formula property...

<property name="IsCurrentUserVoted" formula="select count(*) from vote where userId=Id" />

I'm not positive on the syntax, you might need to use a scalar function to wrap the query. Also, it might be best to run that query only when needed, unless you really need that value every time you get an Entry.