怎样避免在EF自己主动生成的model中的DataAnnotation被覆盖掉

相信非常多人刚接触EF+MVC的时候，会有这个疑问。就是当我们在model类中加验证信息的时候。会在又一次生成model的时候被重写掉。

这里介绍一个方法：

比方我有个Employee类是从数据库中生成到model中的，我们能够在Models目录中创建一个部分类名称与Employee类同名（注意：该类的命名空间必须与自己主动生成的类属于同一个命名空间），类内容为空的就能够。然后在新建的部分类下方再创建一个类（EmployeeMetaData),类中中加上我们须要验证的列与验证信息，然后须要将

[MetadataType(typeof(EmployeeMetaData))]加在新建的Employee类名上方

这时我们在view页面中不用更改代码。这样当我们又一次生成model的时候，我们自定义的部分类Employee就不会受影响了。

以下是例子代码：

从数据库中生成的Employee：

//------------------------------------------------------------------------------

// <auto-generated>

//     This code was generated from a template.

//

//     Manual changes to this file may cause unexpected behavior in your application.

//     Manual changes to this file will be overwritten if the code is regenerated.

// </auto-generated>

//------------------------------------------------------------------------------

namespace ValidationDemo

{

    using System;

    using System.Collections.Generic;

    public partial class Employee

    {

        public Employee()

        {

            this.Employees1 = new HashSet<Employee>();

            this.Orders = new HashSet<Order>();

            this.Territories = new HashSet<Territory>();

        }

        public int EmployeeID { get; set; }

        public string LastName { get; set; }

        public string FirstName { get; set; }

        public string Title { get; set; }

        public string TitleOfCourtesy { get; set; }

        public Nullable<System.DateTime> BirthDate { get; set; }

        public Nullable<System.DateTime> HireDate { get; set; }

        public string Address { get; set; }

        public string City { get; set; }

        public string Region { get; set; }

        public string PostalCode { get; set; }

        public string Country { get; set; }

        public string HomePhone { get; set; }

        public string Extension { get; set; }

        public byte[] Photo { get; set; }

        public string Notes { get; set; }

        public Nullable<int> ReportsTo { get; set; }

        public string PhotoPath { get; set; }

        public Nullable<int> COL1 { get; set; }

        public virtual ICollection<Employee> Employees1 { get; set; }

        public virtual Employee Employee1 { get; set; }

        public virtual ICollection<Order> Orders { get; set; }

        public virtual ICollection<Territory> Territories { get; set; }

    }

}

创建一个部分类。命名为Employee：

using System;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations;

using System.Linq;

using System.Web;

namespace ValidationDemo

{

    [MetadataType(typeof(EmployeeMetaData))]

    public partial class Employee

    {

    }

    public partial class EmployeeMetaData

    {

        public int EmployeeID { get; set; }

        [Required]

        public string LastName { get; set; }

        public string FirstName { get; set; }

        public string Title { get; set; }

        public string TitleOfCourtesy { get; set; }

        public Nullable<System.DateTime> BirthDate { get; set; }

        public Nullable<System.DateTime> HireDate { get; set; }

        public string Address { get; set; }

        public string City { get; set; }

        public string Region { get; set; }

        public string PostalCode { get; set; }

        public string Country { get; set; }

        public string HomePhone { get; set; }

        public string Extension { get; set; }

        public byte[] Photo { get; set; }

        public string Notes { get; set; }

        public Nullable<int> ReportsTo { get; set; }

        public string PhotoPath { get; set; }

        public Nullable<int> COL1 { get; set; }

    }

}

參考文档：

http://www.asp.net/mvc/tutorials/older-versions/models-(data)/validation-with-the-data-annotation-validators-cs

OK,大功告成。