实体框架数据库首先如何修改实体以使它们从基类派生 [英] Entity Framework Database first How to alter entities to make them derive from a base class

问题描述

我有一个已经有数据库的数据库已经包含在其中的数据。我所看到的是所有表共有5列：

• Id-long，key


• IsDeleted，bit


• DateDeleted，SmallDatetime


• LastUpdated，SmallDatetime


• LastUpdatedUser，nvarchar

现在，有一些常见的操作是基于当前在任何地方复制的字段完成的。

我想要的是创建一个只包含这些常见属性的基类和完成的方法，并使每个其他实体都从这个派生出来。

我不需要或想要在数据库本身拥有这个基础实体，这只是我想帮助编码部分。

问题是这是数据库第一，我不能更改数据库，所以我必须使用的是POCO类和EDMX。

我该如何实现？

解决方案

你正在寻找的是类似的东西到TPH（ http://msdn.microsoft.com/en-us/data/jj618292.aspx）

我不认为这可以适用于你，因为你有多个现有的表。

可能的解决方案之一是：

1. 创建一个名为BaseModel的基类（或类似的东西）


2. 将这些属性添加为抽象以强制它们被覆盖


3. 在该基类中创建一个方法来填充这些字段，或创建一个帮助器，它使用BaseModel，IsDeleted，作为参数使用LastUpdated，LastUpdatedUser作为参数并更新模型。


4. 扩展由模型生成的部分类 .tt文件，并继承自BaseModel类。
   

谢谢，
Dave

I have a database already full of tables with data in them. What i have seen is that all tables have 5 columns in common:

• Id-long, key
• IsDeleted, bit
• DateDeleted, SmallDatetime
• LastUpdated, SmallDatetime
• LastUpdatedUser, nvarchar

Now, there are some common operations that are done based on those fields which currently are replicated everywhere

What i want is to create a base class containing just these common attributes and the methods done to them and make every other entity derive from this.

I dont need or want to have this base entity on the database per se, this is just something i want to help the coding part.

The issue is this is Database first, i cannot alter the database so all i have to work with are the POCO classes and the EDMX.

How can i achieve this?

解决方案

What you are looking for is something similar to TPH (http://msdn.microsoft.com/en-us/data/jj618292.aspx)

I don't think this will work for you however, as you have multiple existing tables.

One of the possible solutions is:

1. Create a base class called "BaseModel" (or something like that)
2. Add those properties as abstracts to force them to be overridden
3. Create a method in that base class to populate those fields, or create a helper which takes BaseModel, IsDeleted,LastUpdated, LastUpdatedUser as a parameter and update the model.
4. Extend the partial classes generated by the model.tt file and inherit from the BaseModel class.

Thanks, Dave

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