使用自定义 hql 生成器将 linq-to-nhibernate 扩展

目标是使用 NHibernate 和 Linq 做这样的事情：

Session.Query<MyClass>().Where(x => x.DateGreaterThen(DateTime.Now))

这个例子有点简化，但想法是，在 Where 谓词中，我想调用 MyClass 方法。所以MyClass看起来像：

public class MyClass
{
    public static readonly Expression<Func<MyClass, DateTime, bool>> GreaterThenExpression =
        (x, dt) => x.MyDateTimeProperty > dt.Date;
    private static readonly Func<MyClass, DateTime, bool> GreaterThenFunc = GreaterThenExpression.Compile();
    public Guid Id { get; set; }
    public DateTime MyDateTimeProperty { get; set; }
    public bool DateGreaterThen(DateTime dt)
    {
        return GreaterThenFunc(this, dt);
    }
}

自定义生成器：

public class EntityMethodGenerator<T1, T2, TResult> : BaseHqlGeneratorForMethod
{
    private Expression<Func<T1, T2, TResult>>  _returnValueExpression;
    public EntityMethodGenerator()
    {
        SupportedMethods = new[]
                               {
                                   ReflectionHelper.GetMethodDefinition<MyClass>(myClass => myClass.DateGreaterThen(DateTime.Now))
                               };
    }
    public static void Register(ILinqToHqlGeneratorsRegistry registry, Expression<Action<T1>> method, Expression<Func<T1, T2, TResult>> returnValueExpression)
    {
        var generator = new EntityMethodGenerator<T1, T2, TResult> { _returnValueExpression = returnValueExpression };
        registry.RegisterGenerator(ReflectionHelper.GetMethodDefinition(method), generator);
    }
    public override HqlTreeNode BuildHql(
        MethodInfo method,
        Expression targetObject,
        ReadOnlyCollection<Expression> arguments,
        HqlTreeBuilder treeBuilder,
        IHqlExpressionVisitor visitor)
    {
        return visitor.Visit(_returnValueExpression);
    }
}

最后是自定义生成器注册表：

public class OwnLinqToHqlGeneratorsRegistry : DefaultLinqToHqlGeneratorsRegistry
{
    public OwnLinqToHqlGeneratorsRegistry()
    {
        EntityMethodGenerator<MyClass, DateTime, bool>.Register(this, (myClass) => myClass.DateGreaterThen(DateTime.Now), MyClass.GreaterThenExpression);
    }   
}

但是这不起作用，我System.Data.SqlClient.SqlException : Invalid column name 'dt'.怀疑我的 BuildHql 方法没有正确实现，有什么帮助解决这个问题吗？

顺便说一下，我想在生成器中使用表达式，就像我的GreaterThenExpression一样，而不是BuildHql方法中手动构建 HqlTree