nHibernate - 一个只包含超类型的集合 [英] nHibernate- a Collection which would contain only a supertype

问题描述

我有以下类：


$ p $ class Employee
{
public string Name {get;组; }
}

class HistoricalEmployee：Employee
{
public DateTime TerminationDate {get;组; }
}

class Company
{
public IList< Person> CurrentEmployees {get;组; Employee和HistoricalEmployee是使用table-per-class-map来映射的，所以我们可以使用table-per-class-平等战略。

当我检索CurrentEmployees集合时，我只希望它包含Employee的元素，而不是HistoricalEmployees。当员工死亡时，它们不是HistoricalEmployees。但是他们成为了HistoricalEmployee（还有一些其他的属性，比如终止日期等）。
显然，历史雇员的数量将随着时间的增加而超过员工数量，
所以我不能获取所有HistoricalEmployees，当我只需要当前雇员。

如何（流利）配置集合只检索超类的元素？

我认为这与Polymorphism属性有关，但我无法弄清楚如何做到这一点。

谢谢，

Jhonny

解决方案

好的，我这样做了：

  mapping.HasMany（x => x.CurrentEmployees）
 //.其中（pqa => pqa。 TimeOut！= nul l）
。Where（TerminationDate is null）
  

显然， ）函数在属性上创建一个过滤器，这正是我所需要的。

注意到我使用了字符串版本，并且注释了Func<>版本。

这是因为目前（FNH 1.1），据我所知，Func<>版本不起作用。

希望这可以帮助某人，

J

I have the following classes:

class Employee
{
    public string Name { get; set; }
}

class HistoricalEmployee : Employee
{
    public DateTime TerminationDate { get; set; }
}

class Company
{
    public IList<Person> CurrentEmployees { get; set; }
}

Employee and HistoricalEmployee are mapped using table-per-class-heirarchy strategy.
When I retrieve the CurrentEmployees collection, I want it only to contain elements that are Employee, and NOT HistoricalEmployees.
when an employee 'dies', they're not really deleted,
but they become HistoricalEmployee (with a few more attributes, such as termination date etc.).
Obviously, over time, the number of HistoricalEmployees will exceed the number of Employees by magnitudes,
so I can't fetch all HistoricalEmployees when I only need current Employees.

How can I (fluently) configure the collection to only retrieve elements of the super class?
I think it's something to do with the Polymorphism property, but I couldn't really figure out how to do that.

thanks,
Jhonny

解决方案

Ok, I did this like so:

mapping.HasMany(x => x.CurrentEmployees)
            //.Where(pqa => pqa.TimeOut != null)
            .Where("TerminationDate is null")

apparently, the .Where() function creates a filter on the property, which is exactly what I needed.
notice that I used the string version, and commented-out the Func<> version.
This is because that currently (FNH 1.1), as far as I could determine, the Func<> version doesn't work.
hopes this helps somebody,
J

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