Question

I have a class called LoanApplication, and it has a collection property set up called Workflow. In the mapping file, I am setting the order of retrieval of the Workflow records to sort by Date, so the current workflow is always the first item in the list.

Now I want to query by the current workflow to get LoanApplications that are in a specific workflow step using the Criteria API. I’m not really sure how to do this. Here is how I am mapping the Workflow collection:

<bag name="ApplicationWorkflow" table="PreApplication.ApplicationWorkflow" generic="true" inverse="true" order-by="StartDate DESC"
  cascade="all" lazy="true">
  <key column="ApplicationID" />
  <one-to-many class="ApplicationWorkflow" />
</bag>

Here is how I am retrieving applications (this is where I need to add the filter by Current Workflow functionality):

    public IList<Model.PreApplication.Application> GetCompletedApplications()
    {
        IList<Model.PreApplication.Application> result = null;

        using (ITransaction transaction = this.Session.BeginTransaction())
        {
            result = this.Session.CreateCriteria<Model.PreApplication.Application>()
                .AddOrder(new Order("EnteredDate", false))
                .List<Model.PreApplication.Application>();

            transaction.Commit();
        }

        return result;
    }

Thanks for any help!

Answer 1

So you need to list Applications whose current Workflow is at a specific step? You can use a sub-query to join only the current workflow and then restrict to a specific step.

the desired SQL…

select
    ...
from
    Application app
    inner join ApplicationWorkFlow currWorkFlow on app.id = currWorkFlow.application_id
where
    currWorkFlow.id = (
        select top 1 topFlow.id
        from ApplicationWorkFlow topFlow
        where topFlow.application_id = app.id
        order by topFlow.StartedDate desc
    )
    and currWorkFlow.step = @step

the Criteria to get you there…

session.CreateCriteria<Application>("app")
    .CreateAlias("ApplicationWorkFlow", "currWorkFlow", NHibernate.SqlCommand.JoinType.InnerJoin)
    .Add(Subqueries.PropertyEq("currWorkFlow.id", 
        DetachedCriteria.For<ApplicationWorkFlow>("topFlow")
            .SetMaxResults(1)
            .SetProjection(Projections.Property("topFlow.id"))
            .AddOrder(Order.Desc("topFlow.StartDate"))
            .Add(Restrictions.EqProperty("app.id", "topFlow.Application.id"))))
    .Add(Restrictions.Eq("currWorkFlow.step", step))
    .List<Application>();