CompositeId和Identity_Insert

Question

我的类映射如下：

public class FooMap : ClassMap<Foo> 
{
  public FooMap()
  { 
    Table("Foo");
    LazyLoad();
    CompositeId().KeyProperty(x => x.ID, 
                              kp => kp.ColumnName("Id")
                                      .Type(typeof(long)))
                 .KeyProperty(x => x.ValidFrom);
   }
}

在MSSQL端，Id是标识列，表的PK由Id和ValidFrom组成。

以下是我用来保存的代码：

ISession session = SessionService.GetSession();    
new SqlCommand("SET IDENTITY_INSERT Foo ON",
                session.Connection as SqlConnection)
                .ExecuteNonQuery();

try
{
    // performs various versioning checks,
    // then saves using transaction.
    // The session is the same as above
    GenericDataService.Save(myFoo);
}
finally
{
    new SqlCommand("SET IDENTITY_INSERT Foo OFF",
                    session.Connection as SqlConnection)
                    .ExecuteNonQuery();
}

虽然我将Identity_Insert设置为ON，但我收到以下异常（保留ID并设置新ValidFrom时）：

Cannot insert explicit value for identity column in table 'Foo' when IDENTITY_INSERT is set to OFF.

这是执行的SQL：

INSERT INTO Foo (C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, Id, ValidFrom) 
    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)

有人可以解释为什么我仍然会得到这个例外吗？

Answer 1

如果问题与建议的Nathan Fisher之类的单独事务有关，那么NHibernate的ITransaction.Enlist(IDbCommand)方法应该修复它。尝试这样的事情：

using (var trx = session.BeginTransaction())
{
    ExecuteInNHTransaction(session, "SET IDENTITY_INSERT Foo ON");
    session.Save(myFoo);
    ExecuteInNHTransaction(session, "SET IDENTITY_INSERT Foo OFF");
    trx.Commit();
}

private static void ExecuteInNHTransaction(ISession session, string commandText)
{
    var command = new SqlCommand(commandText,
        (SqlConnection) session.Connection);
    session.Transaction.Enlist(command);
    command.ExecuteNonQuery();
}