Fluent NHibernat-用LINQ查询枚举字段

Transactions:
- TransactionID (PK, Identity, Int)
- TypeID (FK, Int)
- Amount (Decimal)

TransactionTypes:
- TypeID (PK, Identity, Int)
- Type (NVarChar)

在我的应用程序中,它们被定义为:

public class Transaction
{
    public virtual int TransactionID { get; set; }
    public virtual TransactionTypes Type { get; set; }
    public virtual decimal Amount { get; set; }
}

public enum TransactionTypes
{
    Event = 1,
    Product = 2
}

具有以下映射:

public class TransactionMap : ClassMap<Transaction>
{
    public TransactionMap()
    {
        Table("Transactions");
        Id(x => x.TransactionID);
        Map(x => x.Type, "TypeID").CustomType<int>();
        Map(x => x.Amount);
    }
}

除了询问之外,一切正常。当我尝试做:

session.Linq<Transaction>().Where(t => t.Type == TransactionTypes.Event).ToList();

它抛出错误“类型不匹配” NHibernate.Criterion.SimpleExpression System.Int32 Entities.TransactionTypes ".