用流利NHibernate的鉴别器 [英] Using discriminator with Fluent NHibernate

问题描述

我试图创建一个鉴别器列。本专栏将保存许多可用状态之一。就像我的代码将显示每个状态有一个名称以及背景颜色。

 public class Item 
 {
 public virtual int Id {get;组; } 
 public virtual Status ItemStatus {get;组; } 
} 
 
 public abstract class Status 
 {
 private readonly int _id; 
 public static readonly状态Foo = new FooStatus（1）; 
 public static readonly Status Bar = new BarStatus（2）; 
 
 public Status（）
 {
 
} 
 
保护状态（int id）
 {
 _id = id; 
} 
 
 public virtual int Id {get {return _id; }} 
 public abstract string Name {get; } 
 public abstract string BackgroundColor {get; } 
 
 $ b $ public class FooStatus：Status 
 {
 public FooStatus（）
 {
 
} 
 
 public FooStatus（int id）
：base（id）
 {
 
 
 
 public override string Name 
 { 
得到{返回Foo状态; } 
} 
 
 public override string BackgroundColor 
 {
 get {returnWhite; } 
 
 
 $ b $ public class BarStatus：Status 
 {
 public BarStatus（）
 {
 
 } 
 $ b $ public BarStatus（int id）
：base（id）
 {
 
} 
 
 public override string Name 
 {
 get {returnBar Status; } 
} 
 
 public override string BackgroundColor 
 {
 get {returnBlack; } 
 
 
 $ / code $ / pre 
 $ b $这里是我的映射：
  public class ItemMap：ClassMap< Item> 
 {
 public ItemMap（）
 {
 Id（x => x.Id）.GeneratedBy.Identity（）; 
 
 DiscriminateSubClassesOnColumn< int>（ItemStatus，0）.AlwaysSelectWithValue（）; 
 
 
 
 
 $ b $ p 
 $ b基本上，我想要的是如果我设置 ItemStatus 为 Status.Foo ，那么 ItemStatus 列会有一个值1.我现在不会抛出任何异常，但总是插入 ItemStatus 作为 0 。 
 
 
 
这是我使用的插入代码： 
 
 
 使用（var session = sessionFactory.OpenSession（））
使用（var transaction = session.BeginTransaction（））
 {
 var item = new Item 
 {
 ItemStatus = Status.Foo 
}; 
 session.Save（item）; 
 transaction.Commit（）; 
 
 var firstItem = session.Get< Item>（1）; 
 Console.WriteLine（firstItem.ItemStatus.Name）; 
 
 $ / code> 
在哪里可以阅读关于这个主题的使用FNH？
 
 
 
在任何人建议在Google上进行检查之前，我确实搜索了几件事情，但没有在哪里可以找到一个完整的示例。 
 
解决方案 
您的 SubclassMap 看起来像这样： 
 
 
  public class FooStatusMap：SubclassMap< FooStatus> 
 {
 public FooStatusMap（）
 {
 DiscriminatorValue（1）; 
 
 
 
 
 $ b $ p $这个被称为每班级表，你是对的，它看起来不像有很多资源。
 
 
 
我相信如果你不'在 SubclassMap 中调用 DiscriminatorValue ，NHibernate试图通过查看被映射的子类的名字来判别它匹配鉴别器列中的值。
I'm trying to create a discriminator column. This column would hold one of the many statuses available. Like my code will show each status has a name as well as a background color. Each status share the same base class.

Here is my code:
public class Item
{
    public virtual int Id { get; set; }
    public virtual Status ItemStatus { get; set; }
}

public abstract class Status
{
    private readonly int _id;
    public static readonly Status Foo = new FooStatus(1);
    public static readonly Status Bar = new BarStatus(2);

    public Status()
    {

    }

    protected Status(int id)
    {
        _id = id;
    }

    public virtual int Id { get { return _id; } }
    public abstract string Name { get; }
    public abstract string BackgroundColor { get; }
}

public class FooStatus : Status
{
    public FooStatus()
    {

    }

    public FooStatus(int id)
        : base(id)
    {

    }

    public override string Name
    {
        get { return "Foo Status"; }
    }

    public override string BackgroundColor
    {
        get { return "White"; }
    }
}

public class BarStatus : Status
{
    public BarStatus()
    {

    }

    public BarStatus(int id)
        : base(id)
    {

    }

    public override string Name
    {
        get { return "Bar Status"; }
    }

    public override string BackgroundColor
    {
        get { return "Black"; }
    }
}
And here is my mapping:
public class ItemMap : ClassMap<Item>
{
    public ItemMap()
    {
        Id(x => x.Id).GeneratedBy.Identity();

        DiscriminateSubClassesOnColumn<int>("ItemStatus", 0).AlwaysSelectWithValue();
    }
}
Essentially, what I'd like is that if I set ItemStatus to Status.Foo then the ItemStatus column would have a value of 1. What I have now doesn't throw any exceptions but it always inserts ItemStatus as 0.

This is the inserting code I'm using:
        using (var session = sessionFactory.OpenSession())
        using (var transaction = session.BeginTransaction())
        {
            var item = new Item
                           {
                               ItemStatus = Status.Foo
                           };
            session.Save(item);
            transaction.Commit();

            var firstItem = session.Get<Item>(1);
            Console.WriteLine(firstItem.ItemStatus.Name);
        }
Where can I read up on this topic using FNH?

Before anyone suggests be to check on Google I did search several things but no where can I find a full example.
解决方案
Your SubclassMap would look something like this:
public class FooStatusMap : SubclassMap<FooStatus>
{
    public FooStatusMap()
    {
        DiscriminatorValue(1);
    }
}
This is called "table-per-class-hierarchy," and you're right it doesn't look like there are many resources on it out there.

I believe if you don't call DiscriminatorValue in a SubclassMap, NHibernate attempts to discriminate by looking at the name of the subclass being mapped and seeing if it matches up with the value in the discriminator column.

                        
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