如何扩展一个实体框架6.1.3生成的类？ [英] How to extend an Entity Framework 6.1.3 generated class?

问题描述

是否可以扩展实体框架6.1.3生成的类？

Is it possible to extend an Entity Framework 6.1.3 generated class?

我有一个现有的数据库，我已经创建了一个ADO.NET实体数据模型， Visual Studio 2015依次生成了一组类。

I have an existing database to which I have created an ADO.NET Entity Data Model, which in turn Visual Studio 2015 has generated a set of classes.

public partial class WebApplication1Entities : DbContext
{
    public WebApplication1Entities()
        : base("name=WebApplication1Entities")
    {
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        throw new UnintentionalCodeFirstException();
    }
}

我可以手动覆盖WebApplication1Entities以允许动态运行时连接如下：

I can manually override the WebApplication1Entities to allow a dynamic runtime connection as so:

    public WebApplication1Entities(string connectionString) : base(connectionString)
    {
    }

然而，这涉及编辑Visual Studio 2015生成的类，但是我希望更新ADO .NET实体数据模型在将来，Visual Studio将覆盖我对上一个生成的类进行的任何手动更改，而且我已经回到第一个方法，必须手动编辑生成的类。

This however, involves editing the class that Visual Studio 2015 has generated, but should I wish to update the ADO.NET Entity Data Model in the future, Visual Studio will overwrite any manual changes I have made to the previous generated class and I'm back to square one, having to manually edit the generated class.

是否可以创建一个帮助类或类似的扩展现有的 WebApplication1Entities：DbContext ，并允许添加新的重载方法，并继承Visual Studio 2015生成的类的现有方法，如虚拟DbSets。

Is it possible to create a helper class or something similar to extend the existing WebApplication1Entities : DbContext, and allow the addition of the new overloaded method and also inherit the existing methods of the Visual Studio 2015 generated class such as virtual DbSets.

任何帮助将不胜感激： ）

Any help would be much appreciated :-)

推荐答案

正如您在声明中所看到的那样，

As you see in the declaration

public partial class WebApplication1Entities : DbContext

这个类是部分。

所以你可以创建另一个* .cs文件，并将你的代码放在那里（使用相同的命名空间！）：

So you can create another *.cs file and put your code there (use the same namespace!):

public partial class WebApplication1Entities
{
     public WebApplication1Entities(string connectionString) : base(connectionString)
     {
     }        
}

所以当设计师覆盖该文件包含原始类，您的代码保持不变。

So when the designer overwrites the file containing the "original" class, your code stays untouched.

更多关于 partial 类和方法。

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