如何:从同一张表映射(NHibernate)具有不同业务逻辑的多个类? [英] How-to: Mapping (NHibernate) multiple classes with different business logic from the same table?

问题描述

我目前正在使用Brownfield数据库，该数据库包含一个表，该表包含3种不同业务的数据.它与SalesOrders和订单行有关.在旧的应用程序中，我们能够向每个销售订单添加3种类型的订单行:产品，小时费率和文本行. 15年前，这是一种快速而又肮脏的解决方案，可以在Delphi中轻松查询，以将所有行合并到一个datagrid中.每个

I am currently working with a brownfield database which contains a table which holds data for 3 different sorts of business. It has to do with SalesOrders and orderlines. In the old application, we were able to add 3 types of orderlines to each salesorder: products, hourly rates and text lines. 15 years ago, this was a quick and dirty solution to get easy queries in Delphi to get all the lines in one datagrid. Every

现在，我正在尝试使用NHibernate在C#中构建对象模型.由于这3个线型没有真正的业务逻辑连接，因此我制作了3个没有基类的单独实体.但是，我想将这3种类型归为一个列表，以便可以订购它们.

Now I am trying to build the object model in C# using NHibernate. I've made 3 seperate entities without a base class, due to the fact that these 3 line types have no real business logical connection. However, I want to get these 3 types into one list so I can order them.

我考虑过使用继承，每个类使用表，因为表满足要求(没有列具有非null约束).但是，这不是逻辑步骤，因为每种业务类型完全不同(只有共同的地方是userId，描述和备注).也许是一个组成部分?但是如何将属性映射到3个不同的类，而没有基类或除表名之外的任何类型的链接?

I've considered using inheritence, table per class, as the table meets the requirements (no columns with a not-null restraint). This isn't a logical step though, since the business per type is completely different (only things in common are userId, description and remarks). Perhaps a component? but how to map the properties to 3 different classes without a base class or any kind of link except the table name?

我希望你们能理解我写的东西.我还没有真正的代码，我只是在纸上画一些关于如何处理此代码的东西.

I hope you guys understood what I wrote. I have no real code yet, I was just sketching some stuff on paper on how to deal with this code.

这里有人可以帮助我吗?

Anyone here who can help me on my way?

亲切的问候， 特德

推荐答案

您可以在三个实体上放置一个接口，并将其映射为基类，全部映射到同一张表:

You could put an interface on the three entities and map it as a base class, all to the same table:

interface IWhatever 
{
  // central Id for the whole table
  int Id { get; set; }
  // may be some more properties
}

class Product : IWhatever
{
  // ...
}

class HourlyRate : IWhatever
{
  // ...
}

class TextLines : IWhatever
{
  // ...
}

映射:

<class name="IWhatever" table="MyBigTable">

  <id .../>
  <discriminator column="Type"/>
  <subclass name="Product" discriminator-value="P">
    <!-- ... -->
  </subclass>
  <subclass name="HourlyRate" discriminator-value="HR">
    <!-- ... -->
  </subclass>
  <subclass name="TextLines" discriminator-value="TL">
    <!-- ... -->
  </subclass>
</class>

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