1.简单验证

在ASP.Net MVC中，验证是在Controller层，而错误呈现是在View层，Controller层是通过ModelState属性进行验证的,ModelState的状态是通过AddModelError()方法进行 添加的。

而在View层，是通过Html的辅助方法进行呈现的，这两个辅助方法分别是

Html.ValidationMessage()
Html.ValidationSummary()

[AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Create([Bind(Exclude="CustomerId")] Customer customer)
        {
            if (customer.CompanyName.Length == 0)
            {
                ModelState.AddModelError("CompanyName", "CompanyName不能为空");
            }
            if (customer.EmailAddress.Length == 0)
            {
                ModelState.AddModelError("EmailAddress", "EmailAddress不能为空");
            }
            if (!ModelState.IsValid)
            {
                return View();
            }
            try
            {
                _entities.AddToCustomer(customer);
                _entities.SaveChanges();
                return RedirectToAction("Index");
            }
            catch
            {
                return View();
            }
        }

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage" %>


    Create




    
Create

    <%= Html.ValidationSummary("Create was unsuccessful. Please correct the errors and try again.") %>

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

        

            
Fields
            

                NameStyle:
                <%= Html.TextBox("NameStyle") %>
                <%= Html.ValidationMessage("NameStyle", "*") %>
            
            

                Title:
                <%= Html.TextBox("Title") %>
                <%= Html.ValidationMessage("Title", "*") %>
            
            

                FirstName:
                <%= Html.TextBox("FirstName") %>
                <%= Html.ValidationMessage("FirstName", "*") %>
            
            

                MiddleName:
                <%= Html.TextBox("MiddleName") %>
                <%= Html.ValidationMessage("MiddleName", "*") %>
            
            

                LastName:
                <%= Html.TextBox("LastName") %>
                <%= Html.ValidationMessage("LastName", "*") %>
            
            

                Suffix:
                <%= Html.TextBox("Suffix") %>
                <%= Html.ValidationMessage("Suffix", "*") %>
            
            

                CompanyName:
                <%= Html.TextBox("CompanyName") %>
                <%= Html.ValidationMessage("CompanyName", "CompanyName不能为空") %>
            
            

                SalesPerson:
                <%= Html.TextBox("SalesPerson") %>
                <%= Html.ValidationMessage("SalesPerson", "*") %>
            
            

                EmailAddress:
                <%= Html.TextBox("EmailAddress") %>
                <%= Html.ValidationMessage("EmailAddress", "EmailAddress不能为空") %>
            
            

                Phone:
                <%= Html.TextBox("Phone") %>
                <%= Html.ValidationMessage("Phone", "*") %>
            
            

                PasswordHash:
                <%= Html.TextBox("PasswordHash") %>
                <%= Html.ValidationMessage("PasswordHash", "*") %>
            
            

                PasswordSalt:
                <%= Html.TextBox("PasswordSalt") %>
                <%= Html.ValidationMessage("PasswordSalt", "*") %>
            
            

                rowguid:
                <%= Html.TextBox("rowguid") %>
                <%= Html.ValidationMessage("rowguid", "*") %>
            
            

                ModifiedDate:
                <%= Html.TextBox("ModifiedDate") %>
                <%= Html.ValidationMessage("ModifiedDate", "*") %>
            
            

                
            
        

    <% } %>

    

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

如果使用Entityframework生成的Model，数据库设计时为不为空，那么生成的Model层该字段的Nullable属性就为false，即使在Controller没有做简单验证，在View层也会做是否为空的判断的。

2.使用IDataErrorInfo Interface

IDataErrorInfo接口的定义比较简单：

public interface IDataErrorInfo { string this[string columnName] { get; } string Error { get; } }

使用IDataErrorInfo Interface的步骤如下：

针对Model，创建一个Partial类
添加OnChanging和OnChanged Partial方法
实现IDataErrorInfo接口

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel;

namespace MvcApplication4.Models
{
    public partial class Customer:IDataErrorInfo
    {
        private Dictionary<string, string> _errors = new Dictionary<string, string>();

        partial void OnCompanyNameChanging(string value)
        {
            if (value.Trim().Length == 0)
            {
                _errors.Add("CompanyName", "CompanyName is required");
            }
        }

        public string Error
        {
            get
            {
                return string.Empty;
            }
        }

        public string this[string columnName]
        {
            get
            {
                if (_errors.ContainsKey(columnName))
                {
                    return _errors[columnName];
                }
                return string.Empty;
            }
        }
    }
}

3.使用Data Annotation Validators

下载Data Annotations Model Binder sample ，下载地址在http://aspnet.codeplex.com/Release/ProjectReleases.aspx?ReleaseId=24471
添加对 Microsoft.Web.Mvc.DataAnnotations.dll和System.ComponentModel.DataAnnotations.dll 的引用
在Global.asax.cs中的Application_Start()方法中配置
使用Data Annotation Validator Attributes
System.ComponentModel.DataAnnotations命名空间下包括四个属性：
Range:范围验证
ReqularExpression：正则表达式验证
Required：必须验证
StringLength：字符串长度验证
Validation：这是所有验证属性的基类。

using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace MvcApplication4.Models
{
    public class Test
    {
        public int Id { get; set; }

        [Required]
        [StringLength(10)]
        public string Name { get; set; }

        [Required]
        public string Description { get; set; }

        [DisplayName("Price")]
        [Required]
        [RegularExpression(@"^\$?\d+(\.(\d{2}))?$")]
        public decimal UnitPrice { get; set; }

    }
}

作者：深山老林
出处：http://wlb.cnblogs.com/

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