使用DataAnnotations与实体框架 [英] Using DataAnnotations with Entity Framework

问题描述

我已经使用VS2010的实体框架来创建一个简单的人物类，其中包含属性firstName，lastName和email。如果我想附加DataAnnotations，就像在这个 blog post 我有一个小问题，因为我的人类是动态生成的。我可以直接编辑动态生成的代码，但任何时候我必须更新我的模型，所有的验证码将被清除。

第一本能就是创建一个部分类，尝试附加注释，但它抱怨我正在尝试重新定义属性。我不知道您是否可以在C＃中使用C ++中的函数声明来创建属性声明。如果可能的话可能是答案。以下是我尝试的代码片段：

 命名空间PersonWeb.Models 
 {
 public partial class Person 
 {
 [RegularExpression（@（\w | \。）+ @（\w | \。）+，ErrorMessage =电子邮件无效）] 
 public string Email {get;组; } 
 / *错误：类型'Person'已经包含'Email'的定义* / 
} 
} 
  

解决方案

一个好友类或多或少是您的代码片段的方向，除了您的手动编码的部分Person类将有一个内部类，如：

  [MetadataType（typeof（Person.Metadata））] 
 public partial class Person {
私密密码类MetaData {
 [RegularExpression（...）] 
 public string Email {get;组; 
} 
} 
  

或者您可以手动部分Person类和一个单独的Meta类，如：

  [MetadataType（typeof（PersonMetaData））] 
 public partial class Person {} 
 
 public class PersonMetaData {
 [RegularExpression（...）] 
 public string Email; 
} 
  

这些是解决方法，并且映射的Presentation类可能更合适。 p>

I have used the Entity Framework with VS2010 to create a simple person class with properties, firstName, lastName, and email. If I want to attach DataAnnotations like as is done in this blog post I have a small problem because my person class is dynamically generated. I could edit the dynamically generated code directly but any time I have to update my model all my validation code would get wiped out.

First instinct was to create a partial class and try to attach annotations but it complains that I'm trying to redefine the property. I'm not sure if you can make property declarations in C# like function declarations in C++. If you could that might be the answer. Here's a snippet of what I tried:

namespace PersonWeb.Models
{
  public partial class Person
  {
    [RegularExpression(@"(\w|\.)+@(\w|\.)+", ErrorMessage = "Email is invalid")]
    public string Email { get; set; } 
    /* ERROR: The type 'Person' already contains a definition for 'Email' */
  }
}

解决方案

A buddy class is more or less the direction your code snippet is journeying, except your manually coded partial Person class would have an inner class, like:

[MetadataType(typeof(Person.Metadata))]
public partial class Person {
    private sealed class MetaData {
        [RegularExpression(...)]
        public string Email { get; set; }
    }
}

Or you could have your manually partial Person class and a separate Meta class like:

[MetadataType(typeof(PersonMetaData))]
public partial class Person { }

public class PersonMetaData {
[RegularExpression(...)]
public string Email;
}

These are workarounds and having a mapped Presentation class may be more suitable.

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