FluentNHibernate - 将一个类映射到多个表 [英] FluentNHibernate - Mapping a class to multiple tables

问题描述

对不起，一个漫长的问题。但是，值得给予所有的细节，所以请与我一直到最后。

我正在对遗留的数据库，我没有太多的控制。我希望能够将一个类映射到多个数据库表。这里是我的表看看

Lookup

  + -------- + -------------- + ------------ + 
 |列| DataType |属性| 
 + -------- + -------------- + ------------ + 
 | Id | INT | PK | 
 |代码| NVARCHAR（50）| | 
 + -------- + -------------- + ------------ + 
  
 $ b $文化 
  + -------------- + -------------- + ---------- -  + 
 |列| DataType |属性| 
 + -------------- + -------------- + ------------ + 
 | Id | INT | PK | 
 | Culture_Code | NVARCHAR（10）| | 
 + -------------- + -------------- + ------------ + 
  
  Lookup_t9n  
  + ---------------- + --------------- +  - -------------------- + 
 |列| DataType |属性| 
 + ---------------- + --------------- + ------------ --------- + 
 | Id | INT | PK | 
 | Culture_Id | INT | FK到文化表| 
 | Localised_Text | NVARCHAR（MAX）| | 
 + ---------------- + --------------- + ------------ --------- + 
  
正如您所看到的，我有一个查找表所有查找都被存储。查找的显示文本已本地化并存储在单独的表中。该表具有文化表的外键以指示本地化文本存在的文化。 
 
 
 
我的类看起来像这样 
 
 
  public class Lookup {
 
 public virtual int Id {get; set;} 
 
 public virtual string Code {get; set;} 
 
 public virtual string DisplayText {get; set;} 
} 
  
我的FNH映射类看起来像这样
  public class LookupMappings：ClassMap< Lookup> {
 
 public LookupMappings（）
 {
 Table（Lookup）; 
 Id（x => x.Id）.Column（Id）; 
 Map（x => x.Code）.Column（Code）; 
 
 Join（Lookup_t9n，join => {
 join.Map（x => x.DisplayText）.Column（Localised_Text）; //注意这个地方，我的问题在这里
}）
} 
} 
  
上面的映射，在加入部分我想提供一些where子句像 WHERE Lookup_t9n.Culture_Id = Culture.Culture_Id和Culture.Culture_Code = System.Threading。 Thread.CurrentUICulture.CultureCode 。
 
 
 
我知道这不是一个有效的SQL，但表达了我希望的意图。有没有人有任何这样的事情的经验。  
 
 
我可以添加一个映射层，在这里我可以使用与数据库表一一对应的类，然后编写纯c＃将这些类映射回我的 Lookup  class。我宁愿这样做，作为一个临时解决方案。我想知道是否可以删除那个智能NH使用映射层。
解决方案
我没有简单的答案， EM>  CallThis（） 。我想根据我们如何使用类似的东西给你提供建议。该解决方案基于标准映射，将其复杂性隐藏在C＃实体中。这只是一个解决方案的草案，所以我会跳过中间的文化表，并期望在 Lookup_t9n 我们只存储文化名称（ en ， cs  ...）
 
 
 
让我们有这个课程
 
 
  public class Lookup {
 public virtual int Id {get; set;} 
 public virtual string Code {get; set;} 
 //为简单起见，跳过空检查
 public virtual DisplayText {get {return Localizations.First（）。LocalizedText; }} 
公共虚拟IList<本地化>本地化{get; set;} 
} 
 
 public class Localization {//映射到Lookup_t9n 
 public virtual string CultureName {get; set;} 
公共虚拟字符串LocalizedText {get;设置;} 
} 
  
有了这个，我们可以映射 em> 本地化作为 HasMany 。它甚至可以被映射为一个组件（请参阅组件映射的示例） 
 
 
 
现在，我们需要的是引入一个过滤器。 流利的例子。基本文档： 18.1。 NHibernate过滤器。
 $ b $ p 
简化映射
 
过滤器：
 
 
  public class CulturFilter：FilterDefinition 
 {
 public CulturFilter（）
 {
 WithName（CulturFilter）
 .AddParameter（culture，NHibernate.NHibernateUtil.String）; 
 
 $ / code> 
收藏： 
 
 <$ （x => x.Localization）
 .KeyColumn（Id）
 ... 
 .ApplyFilter< CulturFilter>（CultureName =：culture））
 .Cascade.AllDeleteOrphan（）; 
  

最后，我们必须介绍一些AOP过滤器，IInterceptor ...需要）并调整 ISession

  session 
 .EnableFilter （CulturFilter）
 .SetParameter（culture
，System.Globalization.CultureInfo.CurrentCulture.TwoLetterISOLanguageName）; 
  

现在我们有 Localized string based on 当前文化，同时使用本地化值的标准映射作为集合。

Sorry for a lengthy question. But it is worth giving all the details so please bear with me through to the end.

I'm working against a legacy database over which I do not have much control. I want to be able to map a class to multiple database tables. Here is how my tables look

Lookup

+--------+--------------+------------+
| Column |   DataType   | Attributes |
+--------+--------------+------------+
| Id     | INT          | PK         |
| Code   | NVARCHAR(50) |            |
+--------+--------------+------------+

Culture

+--------------+--------------+------------+
|    Column    |   DataType   | Attributes |
+--------------+--------------+------------+
| Id           | INT          | PK         |
| Culture_Code | NVARCHAR(10) |            |
+--------------+--------------+------------+

Lookup_t9n

+----------------+---------------+---------------------+
|     Column     |   DataType    |     Attributes      |
+----------------+---------------+---------------------+
| Id             | INT           | PK                  |
| Culture_Id     | INT           | FK to Culture table |
| Localised_Text | NVARCHAR(MAX) |                     |
+----------------+---------------+---------------------+

As you can see, I have a lookup table where all lookups are stored. The display text for a lookup is localized and stored in a separate table. This table has a foreign key to culture table to indicate the culture for which the localized text exists.

My class looks like this

public class Lookup {

    public virtual int Id {get; set;}

    public virtual string Code {get; set;}

    public virtual string DisplayText {get; set;}
}

And my FNH mapping class looks like this

public class LookupMappings : ClassMap<Lookup> {

    public LookupMappings()
    {
        Table("Lookup");
        Id(x => x.Id).Column("Id");
        Map(x => x.Code).Column("Code");

        Join("Lookup_t9n", join => {
            join.Map(x => x.DisplayText).Column("Localised_Text"); //Note this place, my problem is here
        })
    }
}

In the above mapping, in Join part I want to provide some where clause like WHERE Lookup_t9n.Culture_Id = Culture.Culture_Id AND Culture.Culture_Code = System.Threading.Thread.CurrentUICulture.CultureCode.

I know this is not a valid SQL but conveys the intent I hope. Has anyone have any experience of doing such a thing.

I can add a mapping layer where I can have classes that map one-to-one with database tables and then write plain c# to map those classes back to my Lookup class. I have rather done that as an interim solution. I was wondering if I can remove that mapping layer with some smart NH use.

解决方案

I do not have simple answer, like CallThis(). I would like to give you suggestion, based on how we are using similar stuff. The solution is base on the standard mapping, hidding its complexity in C# Entities. It is just a draft of the solution so I'll skip the middle Culture table, and will expect that in Lookup_t9n we do store just a culture name (en, cs...)

Let's have this class

public class Lookup {
    public virtual int Id {get; set;}
    public virtual string Code {get; set;}
                                     // for simplicity skipping null checks    
    public virtual DisplayText { get { return Localizations.First().LocalizedText; } } 
    public virtual IList<Localization> Localizations {get; set;}
}

public class Localization { // mapped to Lookup_t9n
    public virtual string CultureName {get; set;}
    public virtual string LocalizedText {get; set;}
}

Having this, we can map the collection of Localizations as HasMany. It could even be mapped as a component (see example of component mapping)

Now, what we do need is to introduce a filter. Example with Fluent. The essential documentation: 18.1. NHibernate filters.

Simplified mapping

filter:

public class CulturFilter : FilterDefinition
{
  public CulturFilter()
  {
    WithName("CulturFilter")
        .AddParameter("culture",NHibernate.NHibernateUtil.String);
  }

collection:

HasMany(x => x.Localization)
    .KeyColumn("Id")
    ...
    .ApplyFilter<CulturFilter>("CultureName = :culture"))
    .Cascade.AllDeleteOrphan();

Finally, we have to introduce some AOP filter, IInterceptor... which will be triggered each time (needed) and adjust the ISession

session
   .EnableFilter("CulturFilter")
   .SetParameter("culture"
     ,System.Globalization.CultureInfo.CurrentCulture.TwoLetterISOLanguageName);

And now we have Localized string based on current culture, while using standard mapping of localized values as a collection.

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