NHibernate克服NotSupportedException [英] NHibernate Overcoming NotSupportedException

问题描述

有人知道有什么方法可以克服NotSupportedException吗?我有一个针对用户的方法:

Does anyone know of any way to overcome NotSupportedException? I have a method against a User:

 public virtual bool IsAbove(User otherUser)
 {
     return HeirarchyString.StartsWith(otherUser.HeirarchyString);
 }

我想做

_session.Query<User>.Where(x => loggedInUser.IsAbove(x));

但这会引发NotSupportedException.但是真正的痛苦是使用

But this throws a NotSupportedException. The real pain though is that using

_session.Query<User>.Where(x => loggedInUser.HeirarchyString.StartsWith(x.HeirarchyString));

绝对正常.但是，我不喜欢将其作为解决方案，因为这意味着，如果我更改IsAbove方法的工作方式，则必须记住要更新代码的所有重复位置

works absolutely fine. I don't like this as a solution, however, because it means that if I change how the IsAbove method works, I have to remember all the places where I have duplicated the code whenever I want to update it

推荐答案

命名规范表达式并重复使用，例如:

Name the specification expression and reuse that, e.g:

public Expression<Func<....>> IsAboveSpecification = (...) => ...;

public virtual bool IsAbove(User otherUser)
{
    return IsAboveSpecification(HeirarchyString, otherUser.HeirarchyString);
}

根据需要在查询中重用IsAboveSpecification.如果经常使用IsAbove()方法，则可以在表达式上缓存Compile()方法的结果.

Reuse IsAboveSpecification in the query as needed. If the IsAbove() method is used often use can cache the result of the Compile() method on the expression.

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