相关文章：ASP.NET MVC 入门介绍 (上)
接上文，我们来完善验证功能。在System.ComponentModel.DataAnnotations命名空间中，已经有了一些基本的属性类来实现验证功能，只要把这些属性加到Model的字段上就可以了。具体的属性类可以查MSDN, 下面给出一个例子：
public
class
Movie
{
[Key,DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get ; set ; }
[StringLength( 10 ,MinimumLength = 2 ,ErrorMessage = " 必须是2~10个字符长 " ),Required,Display(Name = " 名称 " )]
public string Title { get ; set ; }
[Display(Name = " 发布日期 " )]
public DateTime ReleaseDate { get ; set ; }
public string Genre { get ; set ; }
[Range( 1 , 100 ,ErrorMessage = " 必须是1~100 " )]
public decimal Price { get ; set ; }
public string Rating { get ; set ; }
}
{
[Key,DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get ; set ; }
[StringLength( 10 ,MinimumLength = 2 ,ErrorMessage = " 必须是2~10个字符长 " ),Required,Display(Name = " 名称 " )]
public string Title { get ; set ; }
[Display(Name = " 发布日期 " )]
public DateTime ReleaseDate { get ; set ; }
public string Genre { get ; set ; }
[Range( 1 , 100 ,ErrorMessage = " 必须是1~100 " )]
public decimal Price { get ; set ; }
public string Rating { get ; set ; }
}
再运行下程序，就可以看到效果:
当然，默认的验证往往并不足够，可以尝试下将日期改为201-01-1，点击Create，就会引发异常。我们可以增加自定义的验证属性来满足验证要求。下面我们来实现一个DateAttribute属性来实现日期格式和日期范围的检查。新建一个动态链接库Biz.Web，添加System.ComponentModel.DataAnnotations引用，新建一个类如下:
using
System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Data.SqlClient;
namespace Biz.Web
{
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false )]
public class DateAttribute:ValidationAttribute
{
public DateAttribute()
{
// set default max and min time according to sqlserver datetime type
MinDate = new DateTime( 1753 , 1 , 1 ).ToString();
MaxDate = new DateTime( 9999 , 12 , 31 ).ToString();
}
public string MinDate
{
get ;
set ;
}
public string MaxDate
{
get ;
set ;
}
private DateTime minDate, maxDate;
// indicate if the format of the input is really a datetime
private bool isFormatError = true ;
public override bool IsValid( object value)
{
// ignore it if no value
if (value == null || string .IsNullOrEmpty(value.ToString()))
return true ;
// begin check
string s = value.ToString();
minDate = DateTime.Parse(MinDate);
maxDate = DateTime.Parse(MaxDate);
bool result = true ;
try
{
DateTime date = DateTime.Parse(s);
isFormatError = false ;
if (date > maxDate || date < minDate)
result = false ;
}
catch (Exception)
{
result = false ;
}
return result;
}
public override string FormatErrorMessage( string name)
{
if (isFormatError)
return " 请输入合法的日期 " ;
return base .FormatErrorMessage(name);
}
}
}
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Data.SqlClient;
namespace Biz.Web
{
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false )]
public class DateAttribute:ValidationAttribute
{
public DateAttribute()
{
// set default max and min time according to sqlserver datetime type
MinDate = new DateTime( 1753 , 1 , 1 ).ToString();
MaxDate = new DateTime( 9999 , 12 , 31 ).ToString();
}
public string MinDate
{
get ;
set ;
}
public string MaxDate
{
get ;
set ;
}
private DateTime minDate, maxDate;
// indicate if the format of the input is really a datetime
private bool isFormatError = true ;
public override bool IsValid( object value)
{
// ignore it if no value
if (value == null || string .IsNullOrEmpty(value.ToString()))
return true ;
// begin check
string s = value.ToString();
minDate = DateTime.Parse(MinDate);
maxDate = DateTime.Parse(MaxDate);
bool result = true ;
try
{
DateTime date = DateTime.Parse(s);
isFormatError = false ;
if (date > maxDate || date < minDate)
result = false ;
}
catch (Exception)
{
result = false ;
}
return result;
}
public override string FormatErrorMessage( string name)
{
if (isFormatError)
return " 请输入合法的日期 " ;
return base .FormatErrorMessage(name);
}
}
}
主要实现IsValid方法，如有需要也可以实现FormatErrorMessage方法。要注意属性的参数只能是有限的几种类型，参考这里。写好以后，把HelloWorld项目添加Biz.Web引用，然后就可以使用了，例如:
[Display(Name
=
"
发布日期
"
),Date(MaxDate
=
"
2012-01-01
"
,ErrorMessage
=
"
2012地球灭亡啦
"
)]
public DateTime ReleaseDate { get ; set ; }
public DateTime ReleaseDate { get ; set ; }
看下效果:
当然，这种方式有许多限制，主要是属性参数的限制，只能是基本类型，而且只能是常量。更复杂的验证规则的添加请看这里:
Implement Remote Validation in ASP.NET MVC.
下面为lndex页面加上一些筛选功能。通过给Index传递参数来实现筛选，在页面添加一个selectbox来筛选Genre字段，把MovieController的方法改成：
public
ViewResult Index(
string
movieGenre)
{
var genre = (from s in db.Movies
orderby s.Genre
select s.Genre).Distinct();
ViewBag.MovieGenre = new SelectList(genre); // 给前台准备下拉列表的数据。
if ( ! string .IsNullOrEmpty(movieGenre))
{
// 筛选
var movies = from s in db.Movies where s.Genre == movieGenre select s;
return View(movies);
}
return View(db.Movies.ToList());
}
{
var genre = (from s in db.Movies
orderby s.Genre
select s.Genre).Distinct();
ViewBag.MovieGenre = new SelectList(genre); // 给前台准备下拉列表的数据。
if ( ! string .IsNullOrEmpty(movieGenre))
{
// 筛选
var movies = from s in db.Movies where s.Genre == movieGenre select s;
return View(movies);
}
return View(db.Movies.ToList());
}
在View页面，添加一个Form，里面放上一个选择框和一个按钮，代码如下:
@using (Html.BeginForm(
"
Index
"
,
"
Movie
"
, FormMethod.Get))
{
< p > Genre: @Html.DropDownList( " MovieGenre " , " 全部 " ) < input type = " submit " value = " 筛选 " /></ p >
}
{
< p > Genre: @Html.DropDownList( " MovieGenre " , " 全部 " ) < input type = " submit " value = " 筛选 " /></ p >
}
效果如下：
