一起谈.NET技术，ASP.NET MVC验证框架中关于属性标记的通用扩展方法

     public   partial   class  User
    {
         public   string  UserName {  get ;  set ; }
         public   string  Password {  get ;  set ; }
         public   string  Address {  get ;  set ; }
         public   string  Telephone {  get ;  set ; }
         public   int  Age {  get ;  set ; }
         public   string  Email {  get ; set ;}
    }

public   class  UserMetadata
    {
        [Required]
        [StringLength( 10 )]

         public   string  UserName {  get ;  set ; }

        [Required]
        [StringLength( 18 )]
        [DataType(DataType.Password)]
         public   string  Password {  get ;  set ; }

        [Required]
        [StringLength( 100 )]
         public   string  Address {  get ;  set ; }

        [Required]
        [DataType(DataType.PhoneNumber)]
         public   string  Telephone {  get ;  set ; }

        [Required]
        [Range( 1 ,  100 )]
         public   int  Age {  get ;  set ; }

        [Required]
        [DataType(DataType.EmailAddress)]
         public   string  Email {  get ;  set ; }
    }

    [MetadataType( typeof (UserMetadata))]
     public   partial   class  User
    { 
        
    }

using  System.ComponentModel.DataAnnotations; 

namespace  MVCValidate.Models
{
     public   partial   class  User
    {
         public   string  UserName {  get ;  set ; }
         public   string  Password {  get ;  set ; }
         public   string  Address {  get ;  set ; }
         public   string  Telephone {  get ;  set ; }
         public   int  Age {  get ;  set ; }
         public   string  Email {  get ; set ;}
    }

    [MetadataType( typeof (UserMetadata))]
     public   partial   class  User
    { 
        
    }
     public   class  UserMetadata
    {
        [Required]
        [StringLength( 10 )]

         public   string  UserName {  get ;  set ; }

        [Required]
        [StringLength( 18 )]
        [DataType(DataType.Password)]
         public   string  Password {  get ;  set ; }

        [Required]
        [StringLength( 100 )]
         public   string  Address {  get ;  set ; }

        [Required]
        [DataType(DataType.PhoneNumber)]
         public   string  Telephone {  get ;  set ; }

        [Required]
        [Range( 1 ,  100 )]
         public   int  Age {  get ;  set ; }

        [Required]
        [DataType(DataType.EmailAddress)]
         public   string  Email {  get ;  set ; }
    }

}

using  System.Collections.Generic;
using  System.ComponentModel;
using  System.ComponentModel.DataAnnotations;
using  System.Linq;
using  xVal.ServerSide;

namespace  MVCValidate.Models
{
     internal   static   class  DataAnnotationsValidationRunner
    {
         //  TODO: DOES NOT SUPPORT METADATA TYPE
         /// // Warning: For some reason, DataTypeAttribute.IsValid() always returns "true", regardless of whether
         /// // it is actually valid. Need to improve this test runner to fix that.
         // public static IEnumerable<ErrorInfo> GetErrors(object instance)
         // {
         //     return from prop in TypeDescriptor.GetProperties(instance).Cast<PropertyDescriptor>()
         //            from attribute in prop.Attributes.OfType<ValidationAttribute>()
         //            where !attribute.IsValid(prop.GetValue(instance))
         //            select new ErrorInfo(prop.Name, attribute.FormatErrorMessage(string.Empty), instance);
         // }

         ///   <summary>
         ///  Get any errors associated with the model also investigating any rules dictated by attached Metadata buddy classes.
         ///   </summary>
         ///   <param name="instance"></param>
         ///   <returns></returns>
         public   static  IEnumerable < ErrorInfo >  GetErrors( object  instance)
        {
            var metadataAttrib  =  instance.GetType().GetCustomAttributes( typeof (MetadataTypeAttribute),  true ).OfType < MetadataTypeAttribute > ().FirstOrDefault();
            var buddyClassOrModelClass  =  metadataAttrib  !=   null   ?  metadataAttrib.MetadataClassType : instance.GetType();
            var buddyClassProperties  =  TypeDescriptor.GetProperties(buddyClassOrModelClass).Cast < PropertyDescriptor > ();
            var modelClassProperties  =  TypeDescriptor.GetProperties(instance.GetType()).Cast < PropertyDescriptor > ();

             return  from buddyProp  in  buddyClassProperties
                   join modelProp  in  modelClassProperties on buddyProp.Name equals modelProp.Name
                   from attribute  in  buddyProp.Attributes.OfType < ValidationAttribute > ()
                    where   ! attribute.IsValid(modelProp.GetValue(instance))
                   select  new  ErrorInfo(buddyProp.Name, attribute.FormatErrorMessage( string .Empty), instance);
        }
    }
}

using  System;
using  System.Collections.Generic;
using  System.Linq;
using  System.Web;
using  System.Web.Mvc;
using  System.Web.Mvc.Ajax;

using  MVCValidate.Models;
using  xVal.ServerSide;

namespace  MVCValidate.Controllers
{
     public   class  UserController : Controller
    {
        [AcceptVerbs(HttpVerbs.Post)]
         public  ActionResult Create(User user)
        {
            var errors  =  DataAnnotationsValidationRunner.GetErrors(user);
             if  (errors.Any())
            {
                 new  RulesException(errors).AddModelStateErrors(ModelState, " user " );
            }

             return  View();
        }
    }
}

<% @ Page Language = " C# "  Inherits = " System.Web.Mvc.ViewPage<MVCValidate.Models.User> "   %>

<! DOCTYPE html PUBLIC  " -//W3C//DTD XHTML 1.0 Transitional//EN "   " http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd " >

< html xmlns = " http://www.w3.org/1999/xhtml "   >
< head runat = " server " >
     < title > Create </ title >
</ head >
< body >
     <%=  Html.ValidationSummary( " Create was unsuccessful. Please correct the errors and try again. " )  %>

     <%   using  (Html.BeginForm()) { %>

         < fieldset >
             < legend > Fields </ legend >
             < p >
                 < label  for = " UserName " > UserName: </ label >
                 <%=  Html.TextBox( " user.UserName " )  %>
                 <%=  Html.ValidationMessage( " user.UserName " ) %>
             </ p >
             < p >
                 < label  for = " Password " > Password: </ label >
                 <%=  Html.TextBox( " user.Password " )  %>
                 <%=  Html.ValidationMessage( " user.Password " ) %>
             </ p >
             < p >
                 < label  for = " Address " > Address: </ label >
                 <%=  Html.TextBox( " user.Address " ) %>
                 <%=  Html.ValidationMessage( " user.Address " ) %>
             </ p >
             < p >
                 < label  for = " Telephone " > Telephone: </ label >
                 <%=  Html.TextBox( " user.Telephone " ) %>
                 <%=  Html.ValidationMessage( " user.Telephone " ) %>
             </ p >
             < p >
                 < label  for = " Age " > Age: </ label >
                 <%=  Html.TextBox( " user.Age " ) %>
                 <%=  Html.ValidationMessage( " user.Age " ) %>
             </ p >
             < p >
                 < label  for = " Email " > Email: </ label >
                 <%=  Html.TextBox( " user.Email " ) %>
                 <%=  Html.ValidationMessage( " user.Email " ) %>
             </ p >
             < p >
                 < input type = " submit "  value = " Create "   />
             </ p >
         </ fieldset >

     <%  }  %>

     < div >
         <%= Html.ActionLink( " Back to List " ,  " Index " )  %>
     </ div >

</ body >
</ html >