Using a stored procedure and NHibernate to insert a record

Normally the parameterized SQL works great for CRUD, but I have one instance where I want to use a stored procedure to do an insert.

My HBM file has the following (along with a bunch of other properties, bags, etc)

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="MyProject.Entities" assembly="MyProject">
  <class name="MyProject.Entities.Policy, MyProject" table="dbo.Policy" lazy="true">
    <id name="Id" column="[PolicyId]">
      <generator class="native" />
    </id>
    <sql-insert>exec spInsertPolicy ?,?,?,?,?,?,?</sql-insert>
  </class>
</hibernate-mapping>

The number of question marks in the sql-insert matches the number of properties and many-to-one relationships (there isn't a question mark for the Id).

I'm getting the following exception. If I switch the generator to "increment" it works, but I don't want to do that because other processes are permitted to save to the database.

NHibernate.HibernateException: The database returned no natively generated identity value
       at NHibernate.Id.IdentifierGeneratorFactory.GetGeneratedIdentity(IDataReader rs, IType type, ISessionImplementor session)
       at NHibernate.Id.Iden开发者_JAVA百科tityGenerator.InsertSelectDelegate.ExecuteAndExtract(IDbCommand insert, ISessionImplementor session)
       at NHibernate.Id.Insert.AbstractReturningDelegate.PerformInsert(SqlCommandInfo insertSQL, ISessionImplementor session, IBinder binder)
       at NHibernate.Persister.Entity.AbstractEntityPersister.Insert(Object[] fields, Boolean[] notNull, SqlCommandInfo sql, Object obj, ISessionImplementor session)
       at NHibernate.Persister.Entity.AbstractEntityPersister.Insert(Object[] fields, Object obj, ISessionImplementor session)
       at NHibernate.Action.EntityIdentityInsertAction.Execute()
       at NHibernate.Engine.ActionQueue.Execute(IExecutable executable)
       at NHibernate.Event.Default.AbstractSaveEventListener.PerformSaveOrReplicate(Object entity, EntityKey key, IEntityPersister persister, Boolean useIdentityColumn, Object anything, IEventSource source, Boolean requiresImmediateIdAccess)

Any suggestions? Thanks.

The stored procedure has to return the generated ID for the inserted record, i.e. a SELECT SCOPE_IDENTITY() at the end of the sproc if you're using SQL Server.