Hibernate version:2.1

Name and version of the database you are using:postgres

We have a user that has a method

Set getOrders()

which maps to the orders table

In the orders table we have a subset of those orders that completed. I would like to have another method

Set getCompletedOrders()

which would effectively return -
SELECT orders FROM orders WHERE Completed = true and userid = x;

What is the easiest way to do this? Can we specify a conditional in the mapping, or could be use a view, or should we do this with a separate bit of HQL?

Any suggestions?
Thanks

You should use either HQL with that query, or return a new java collection backed by the existing collection (the one returned by getOrders). The first option is good if you expect the results to change frequently, especially if some other app is setting orders to complete. Using a new collection backed by the existing one avoids having to go back to the database, which is often a good idea.

Thanks tenwit.

This is in the Users persistent class, so I assumme the recommendation is to implement get all orders there.

Do I need to relate Users to a new class CompletedOrder which is based on a query or view to then bring back the subset?

I'll begin to knock that up and see how it looks.

Thanks

Well my preference would be for the backed collection, as you don't have to go back to the database for it. But if you wanted to get a new collection of just the completed orders, then you'd just use a HQL query with the appropriate "where status = completed" or whatever.

Do you understand the idea of backing a collection? You basically want to store the "real" collection (the one returned from getOrders()) inside a new collection (AbstractSet) object, and have the iterator figure out what the next completed order is, instead of the usual next order.

Thanks.

I understand what you are saying about the backed collection, but don't like it. Reducing a list of java objects when the list could be 100's and 1000's is not very efficient, so I think we will either go for the HQL or what I prefer, if it will work is the view on to the data and let the view do the mapping and the query and that way you have the class which is clean, and you can implement any custom behaviour on the completed orders.

Have you done anything like this?

Has anyone else any examples of mapping to a view? Does it work, is it practical? It sounds good in theory!

It deos work, though you have to use an sql-query, because if you use a normal query then hibernate will go to the table associated with the queried class, not the view. And if you're going to write a query, why not use normal HQL and put the where in there? As I understand it, it should be just as efficient as a view, as it uses PreparedStatements which are precompiled, just like views are. Though views might be indexable.. hmm, where did I put my SQL For Dummies book...