Many-to-one with formula

Question

I have an NHibernate mapping file I want to convert to fluent. I'm stuck with this one particular case:

<many-to-one name="LastChildRevision" update="false" not-found="ignore" access="readonly" fetch="join">
    <formula>(SELECT TOP(1) CHILD_REVISION.CHILD_REVISION_ID FROM CHILD_REVISION WHERE CHILD_REVISION.PARENT_ID = PARENT_ID ORDER BY CHILD_REVISION.REVISION_NUMBER DESC)</formula>
</many-to-one>

My class has:

public virtual IList<ChildRevision> ChildRevisions { get; set; }

public virtual ChildRevision LastChildRevision
{
    get
    {
        return this.ChildRevisions.OrderBy(o => o.RevisionNumber).LastOrDefault();
    } 
}

How can I translate this to Fluent NHibernate? When I try this:

References(x => x.LastChildRevision)
    .Formula("(SELECT TOP(1) CHILD_REVISION.CHILD_REVISION_ID FROM CHILD_REVISION WHERE CHILD_REVISION.PARENT_ID = PARENT_ID ORDER BY CHILD_REVISION.REVISION_NUMBER DESC)")
    .Access
    .ReadOnly()
    .Fetch
    .Join();

I get this:

Invalid column name 'LastChildRevision_id'.

Thanks!

Answer 1

I know I asked this question a long time ago, but I decided to revisit Fluent NHibernate, and here's what I came up with:

References(x => x.LastChildRevision)
    .Column("PARENT_ID")
    .Not.Insert()
    .Not.Update()
    .Access.ReadOnly()
    .NotFound.Ignore()
    .Cascade.None()
    .Formula("(SELECT TOP(1) CHILD_REVISION.CHILD_REVISION_ID FROM CHILD_REVISION WHERE CHILD_REVISION.PARENT_ID = PARENT_ID ORDER BY CHILD_REVISION.REVISION_NUMBER DESC)");

Answer 2

there was a bug you might hit. Try clearing the columns first

References(x => x.LastChildRevision)
    .Columns.Clear()
    .Formula("(SELEC ...