NHibernate extract DBTransaction from Session

I have an legacy db where some stored proc calculates the row ids for all the tables. Now I want to overwrite the IIdentifierGenerator as hinted at this page http://www.richter-web.info/Wordpress/?p=132 just to avoid the Id(x => x.id).GenereatedBy.Assigned.

Now as I save some object,of course inside an Nhibernate transaction, named AppendixHierarchy, then as soon as it gets into ATKIdGenerator.Generate and it starts command.ExecuteNonQuery() I receive some exception ExecuteNonQuery requires the command to have a transaction when the connection assigned to the command is in a pendi开发者_运维技巧ng local transaction. The Transaction property of the command has not been initialized.

How can I extract the DB Transaction from the Nhibernate session object, in order to attach it to the command?

I used the FluentMapping for the poco

 public AppendixHierarchyMap()
        {
            Table("appendixHierarchy");
            Id(x => x.id).GeneratedBy.Custom(typeof(ATKIdGenerator), a => a.AddParam("TableName", "appendixHierarchy"));
.....

And here is the Id Generator

public class ATKIdGenerator : IIdentifierGenerator, IConfigurable
    {

        private string TableName { get; set; }
        #region IIdentifierGenerator Members

        public object Generate(NHibernate.Engine.ISessionImplementor session, object obj)
        {
            IDbCommand command = new SqlCommand();
            command.Connection = session.Connection;
            //transaction.Enlist(command);
            command.CommandType = CommandType.StoredProcedure;
            command.CommandText = "dbo.ups_GetNewId";
            // Set input parameters   
            var parm = new SqlParameter("@tableName", SqlDbType.VarChar);
            parm.Value = TableName;
            command.Parameters.Add(parm);
            // Set output parameter   
            var outputParameter = new SqlParameter("@id", SqlDbType.Int);
            outputParameter.Direction = ParameterDirection.Output;
            command.Parameters.Add(outputParameter);
            // Set a return value   
            var returnParameter = new SqlParameter("@RETURN_VALUE", SqlDbType.Int);
            returnParameter.Direction = ParameterDirection.ReturnValue;
            command.Parameters.Add(returnParameter);
            // Execute the stored procedure   
            command.ExecuteNonQuery();
            return (int)((SqlParameter)command.Parameters["@id"]).Value;    
        }

        #endregion

        #region IConfigurable Members

        public void Configure(NHibernate.Type.IType type, IDictionary<string, string> parms, NHibernate.Dialect.Dialect d)
        {
            TableName = parms["TableName"];
        }

        #endregion
    }

I think you need to open another connection in generate method rather then re-using one on the session.