Model Validation in Asp.net MVC-阿里云开发者社区

本文用于记录Pro ASP.NET MVC 3 Framework中阐述的数据验证的方式。

先说服务器端的吧。最简单的一种方式自然是直接在Action方法中来进行了，如下：

[HttpPost]
         public ViewResult MakeBooking(Appointment appt)
        {
             if (String.IsNullOrWhiteSpace(appt.ClientName))
            {
                ModelState.AddModelError( " ClientName ", " Please enter your name ");
            }
             if (ModelState.IsValidField( " Date ") && DateTime.Now > appt.Date)
            {
                ModelState.AddModelError( " Date ", " Please enter a date in the future ");
            }
             if (!appt.TermsAccepted)
            {
                ModelState.AddModelError( " TermsAccepted ", " You must accept the terms ");
            }
             if (ModelState.IsValidField( " ClientName ") && ModelState.IsValidField( " Date ") &&
                appt.ClientName == " Joe " && appt.Date.DayOfWeek == DayOfWeek.Monday)
            {
                ModelState.AddModelError( "", " Joe cannot book appointments on Mondays ");
            }

             if (ModelState.IsValid)
            {
                repository.SaveAppointment(appt);
                 return View( " Completed ", appt);
            }
             else
            {
                 return View();
            }
        }

补充Appointment类源码如下：

   public class Appointment
    {
         public string ClientName { get; set; }

        [DataType(DataType.Date)]
         public DateTime Date { get; set; }

         public bool TermsAccepted { get; set; }
    }

可以看到，Appointment类很POCO，其中Date属性上的DataType属性，不过是标注Date属性值为DateTime的Date部分（去掉Time部分）。再看action内部，将传入的appointment对象属性进行了一个遍历校验。最后，ModelState.AddModelError("", "Joe cannot book appointments on Mondays"); 是标注一个对象模型级别的错误（方法的key参数为空），模型级别错误可以标注多个，它们均将通过@Html.ValidationSummary()显示错误信息。

上述action对应的view为：

@model PageValidation.Models.Appointment

@{
    ViewBag.Title = " Make A Booking ";
}
<h4>Book an Appointment</h4>
@using (Html.BeginForm())
{
    @Html.ValidationSummary();

    <p>
        Your name: @Html.EditorFor(m => m.ClientName)
        @Html.ValidationMessageFor(m => m.ClientName)
    </p>
    <p>
        Appointment Date: @Html.EditorFor(m => m.Date)
        @Html.ValidationMessageFor(m => m.Date)
    </p>
    <p>
        @Html.EditorFor(m => m.TermsAccepted) I accept the terms & conditions
        @Html.ValidationMessageFor(m => m.TermsAccepted)
    </p>
    <input type= " submit " value= " Make Booking " />
}

这个时候，运行程序，神马都不填写然后提交时，页面提示如下：

如果不想form中错误提示重复（顶部的summary和顶部的detail），将@Html.ValidationSummary(); 更新为@Html.ValidationSummary(true); 即可。这个时候，顶部Validation Summary部分只会提示model-level错误了，比如上文中的ModelState.AddModelError("", "Joe cannot book appointments on Mondays");。关于@Html.ValidationSummary()更多细节，请MSDN。

另外，还有一个view的问题是，Firefox和Chrome等一些浏览器上，对checkbox样式的设置不取作用，上图中的效果是通过在checkbox外层包一个div，将checkbox样式转移到div上来实现的。具体为：在项目Views\Shared\EditorTemplates目录下，建立一个Boolean.cshtml文件以覆盖asp.net mvc默认的行为。文件内容如下：

@model bool?

@if (ViewData.ModelMetadata.IsNullableValueType)
{
    @Html.DropDownListFor(m => m, new SelectList( new[] { " Not Set ", " True ", " False " }, Model));
}
else
{
    ModelState state = ViewData.ModelState[ViewData.ModelMetadata.PropertyName];
     bool value = Model ?? false;
     if (state != null && state.Errors.Count > 0)
    {
    <div class = " input-validation-error " style= " float: left " >
        @Html.CheckBox( "" , value)
    </div>
    }
     else
    {
    @Html.CheckBox( "", value)
    }
}

服务器端验证第2种方式是通过Model Binder了。我们继承DefaultModelBinder来写一个Appointment需要的类：

   public class ValidatingModelBinder : DefaultModelBinder
    {
         protected override void SetProperty(ControllerContext controllerContext, ModelBindingContext bindingContext,
            PropertyDescriptor propertyDescriptor, object value)
        {
             // make sure we call the base implementation
             base.SetProperty(controllerContext, bindingContext, propertyDescriptor, value);

             // perform our property-level validation
             switch (propertyDescriptor.Name)
            {
                 case " ClientName ":
                     if ( string.IsNullOrEmpty(( string)value))
                    {
                        bindingContext.ModelState.AddModelError( " ClientName ", " Please enter your name ");
                    }
                     break;
                 case " Date ":
                     if (bindingContext.ModelState.IsValidField( " Date ") && DateTime.Now > ((DateTime)value))
                    {
                        bindingContext.ModelState.AddModelError( " Date ", " Please enter a date in the future ");
                    }
                     break;
                 case " TermsAccepted ":
                     if (!(( bool)value))
                    {
                        bindingContext.ModelState.AddModelError( " TermsAccepted ", " You must accept the terms ");
                    }
                     break;
            }
        }

         protected override void OnModelUpdated(ControllerContext controllerContext, ModelBindingContext bindingContext)
        {
             // make sure we call the base implementation
             base.OnModelUpdated(controllerContext, bindingContext);

            Appointment model = bindingContext.Model as Appointment;
             // apply our model-level validation
             if (model != null && bindingContext.ModelState.IsValidField( " ClientName ") && bindingContext.ModelState.IsValidField( " Date ")
                && model.ClientName == " Joe " && model.Date.DayOfWeek == DayOfWeek.Monday)
            {
                bindingContext.ModelState.AddModelError( "", " Joe cannot book appointments on Mondays ");
            }
        }
    }

其中，OnModelUpdated方法是当给model所有属性赋值时触发，SetProperty方式是当单个属性变化时即触发。接下来要做的，就是在global的Application_Start方法中注册了：

ModelBinders.Binders.Add( typeof(Appointment), new ValidatingModelBinder());

然后，MakeBooking action就可以解脱出来，只需要如下几行代码：

   if (ModelState.IsValid)
            {
                repository.SaveAppointment(appt);
                 return View( " Completed ", appt);
            }
             else
            {
                 return View();
            }

此时，效果和第1种方式完全一样。

第3种方式是通过MetaData了。Asp.net MVC内置了5个meta data验证属性：Compare、Range、RegularExpression、Required、StringLength。基于这5个属性的一些限制，为了更适切Appointment类，自定义几个验证属性如下：

futureDate验证属性：

   public class FutureDateValidatorAttribute : ValidationAttribute
    {
         public override bool IsValid( object value)
        {
             var isDate = value is DateTime;
             if(isDate)
            {
                 var date = Convert.ToDateTime(value);
                 if (date <= DateTime.Now)
                {
                     return false;
                }
            }

             return true;
        }
    }

MustBeTrue验证属性：

     public class MustBeTrueAttribute : ValidationAttribute
    {
         public override bool IsValid( object value)
        {
             return value is bool && ( bool)value;
        }
    }

Appointment验证属性：

   public class AppointmentValidatorAttribute : ValidationAttribute
    {
         public AppointmentValidatorAttribute()
        {
            ErrorMessage = " Joe cannot book appointments on Mondays ";
        }

         public override bool IsValid( object value)
        {
            Appointment app = value as Appointment;
             if (app == null || string.IsNullOrEmpty(app.ClientName) || app.Date == null)
            {
                 // we don't have a model of the right type to validate, or we don't have
                 // the values for the ClientName and Date properties we require
                 return true;
            }
             else
            {
                 return !(app.ClientName == " Joe " && app.Date.DayOfWeek == DayOfWeek.Monday);
            }
        }
    }

再来定义Appointment类：

[AppointmentValidator]
     public class Appointment
    {
        [Required(ErrorMessage = " Please enter your name ")]
         public string ClientName { get; set; }

        [DataType(DataType.Date)]
        [FutureDateValidator(ErrorMessage = " You must enter a date in the future ")]
         public DateTime Date { get; set; }

         // [Range(typeof(bool), "true", "true", ErrorMessage = "You must accept the terms")]
        [MustBeTrue(ErrorMessage = " You must accept the terms ")]
         public bool TermsAccepted { get; set; }
    }

第4种方式：通过实现IValidatableObject接口，定义自验证model。还是Appointment类，如下：

   public class Appointment : IValidatableObject
    {
         public string ClientName { get; set; }

        [DataType(DataType.Date)]
         public DateTime Date { get; set; }

         public bool TermsAccepted { get; set; }

         public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
        {
            List<ValidationResult> errors = new List<ValidationResult>();
             if ( string.IsNullOrEmpty(ClientName))
            {
                errors.Add( new ValidationResult( " Please enter your name ", new string[] { " ClientName " }));
            }
             if (DateTime.Now > Date)
            {
                errors.Add( new ValidationResult( " Please enter a date in the future ", new string[] { " Date " }));
            }
             if (errors.Count == 0 && ClientName == " Joe "
                && Date.DayOfWeek == DayOfWeek.Monday)
            {
                errors.Add( new ValidationResult( " Joe cannot book appointments on Mondays "));
            }
             if (!TermsAccepted)
            {
                errors.Add( new ValidationResult( " You must accept the terms ", new string[] { " TermsAccepted " }));
            }
             return errors;
        }
    }

可以看到，它的核心不过是：将类对象验证内容移入到Valiate方法中。

第5种方式，通过继承ModelValidationProvider，创建自定义ValidationProvider. 如下：

   public class CustomValidationProvider : ModelValidatorProvider
    {
         public override IEnumerable<ModelValidator> GetValidators(ModelMetadata metadata, ControllerContext context)
        {
             if (metadata.ContainerType == typeof(Appointment))
            {
                 return new ModelValidator[] {
                     new AppointmentPropertyValidator(metadata, context)
                };
            }
             else if (metadata.ModelType == typeof(Appointment))
            {
                 return new ModelValidator[] {
                     new AppointmentValidator(metadata, context)
                };
            }

             return Enumerable.Empty<ModelValidator>();
        }
    }

AppointmentPropertyValidator代码如下：

   public class AppointmentPropertyValidator : ModelValidator
    {
         public AppointmentPropertyValidator(ModelMetadata metadata, ControllerContext context)
            : base(metadata, context)
        {
        }

         public override IEnumerable<ModelValidationResult> Validate( object container)
        {
            Appointment appt = container as Appointment;
             if (appt != null)
            {
                 switch (Metadata.PropertyName)
                {
                     case " ClientName ":
                         if ( string.IsNullOrEmpty(appt.ClientName))
                        {
                             return new ModelValidationResult[]
                                       {
                                            new ModelValidationResult
                                               {
                                                    // MemberName = "ClientName",
                                                   Message = " Please enter your name "
                                               }
                                       };
                        }
                         break;
                     case " Date ":
                         if (appt.Date == null || DateTime.Now > appt.Date)
                        {
                             return new ModelValidationResult[]
                                       {
                                            new ModelValidationResult
                                               {
                                                   MemberName = "",
                                                   Message = " Please enter a date in the future "
                                               }
                                       };
                        }
                         break;
                     case " TermsAccepted ":
                         if (!appt.TermsAccepted)
                        {
                             return new ModelValidationResult[]
                                       {
                                            new ModelValidationResult
                                               {
                                                   MemberName = "",
                                                   Message = " You must accept the terms "
                                               }
                                       };
                        }
                         break;
                }
            }
             return Enumerable.Empty<ModelValidationResult>();
        }
    }

注意，上文代码中MemberName不能填写，获取赋值为空，否则error提交到ModelState时，key值会重叠，比如ClientName会成为ClientName.ClientName。AppointmentValidator代码如下：

   public class AppointmentValidator : ModelValidator
    {
         public AppointmentValidator(ModelMetadata metadata, ControllerContext context)
            : base(metadata, context)
        {
        }

         public override IEnumerable<ModelValidationResult> Validate( object container)
        {
            Appointment appt = (Appointment)Metadata.Model;
             if (appt.ClientName == " Joe " && appt.Date.DayOfWeek == DayOfWeek.Monday)
            {
                 return new ModelValidationResult[]
                                       {
                                            new ModelValidationResult
                                               {
                                                   MemberName = "",
                                                   Message = " Joe cannot book appointments on Mondays "
                                               }
                                       };
            }

             return Enumerable.Empty<ModelValidationResult>();
        }
    }

做完这些工作，然后就是注册启用CustomerValidationProvider了。在Application_Start中加入：

ModelValidatorProviders.Providers.Add(new CustomValidationProvider());

就完毕了。

关于CustomerValidationProvider这种方式，作者建议仅用于复杂场合。如：需要从db中动态加载validation rule，或者实现自己的一些验证框架时才使用。这里有一个案例：http://www.codeproject.com/Articles/463900/Creating-a-custom-ModelValidatorProvider-in-ASP-NE

好吧，再看浏览器端的验证。

第1步先启用客户端验证：

或者在Application_Start中增加：

HtmlHelper.ClientValidationEnabled = true;
HtmlHelper.UnobtrusiveJavaScriptEnabled = true;

还有，view当中确保没有：

HtmlHelper.ClientValidationEnabled = false;

默认情况下，它是true。如果要禁用，上述3个区域任意一个设置为false即可。

第2步，view中加载4个必须文件：

第3步，据说最简单的方式是利用meta data属性：

[AppointmentValidator]
     public class Appointment
    {
        [Required(ErrorMessage = " Please enter your name ")]
        [StringLength( 10, MinimumLength = 3, ErrorMessage = " Please enter a string of whose length is between 3 and 10 ")]
        [EmailAddress]
         public string ClientName { get; set; }

        [DataType(DataType.Date)]
         [FutureDateValidator(ErrorMessage = "You must enter a date in the future")]
   public DateTime Date { get; set; }

[MustBeTrue(ErrorMessage = " You must accept the terms ")]
         public bool TermsAccepted { get; set; }
    }

其中EmailAddress是新实现的一个可供客户端验证用的metadata属性。如下：

     public class EmailAddressAttribute : ValidationAttribute, IClientValidatable
    {
         private static readonly Regex emailRegex = new Regex( " .+@.+\\..+ ");

         public EmailAddressAttribute()
        {
            ErrorMessage = " Enter a valid email address ";
        }

         public override bool IsValid( object value)
        {
             return ! string.IsNullOrEmpty(( string) value) &&
                   emailRegex.IsMatch(( string) value);
        }

         public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
        {
             return new List<ModelClientValidationRule>
                       {
                            new ModelClientValidationRule
                               {
                                   ValidationType = " email ",
                                   ErrorMessage = this.ErrorMessage
                               },
                            // new ModelClientValidationRule
                            //     {
                            //         ValidationType = "required",
                            //         ErrorMessage = this.ErrorMessage
                            //     }
                       };
        }
    }

它实现了一个IClientValidatable 接口，所以能够直接在客户端交互。

关于它的实现原理，它不过是在server端将view上需要验证的全部信息都render并且隐藏在页面，然后基于jQuery的validation组件来交互。看一下html片段：

< p >
         Your name: < input data-val ="true" data-val-email ="Enter a valid email address" data-val-length ="Please enter a string of whose length is between 3 and 10" data-val-length-max ="10" data-val-length-min ="3" data-val-required ="Please enter your name" id ="ClientName" name ="ClientName" type ="text" value ="" />

         < span class ="field-validation-valid" data-valmsg-for ="ClientName" data-valmsg-replace ="true" ></ span >

     </ p >

     < p >

        Appointment Date: < input class ="text-box single-line" data-val ="true" data-val-remote ="&#39;Date&#39; is invalid." data-val-remote-additionalfields ="*.Date" data-val-remote-url ="/Appointment/ValidateDate" data-val-required ="The Date field is required." id ="Date" name ="Date" type ="text" value ="2012/10/16" />

         < span class ="field-validation-valid" data-valmsg-for ="Date" data-valmsg-replace ="true" ></ span >
     </ p >

所以，在客户端，其实你可以脱离mvc框架自己来写。如：

$(document).ready( function () {
$('form').validate({
errorLabelContainer: '#validtionSummary',
wrapper: 'li',
rules: {
ClientName: {
required: true,
}
},
messages: {
ClientName: "Please enter your name"
}
});
});

同时，在view中render时，你也可以按照自己的方式来做。如将原有的ClientName显示方式换为：

    <p>
         Your name: @Html.TextBoxFor(m => m.ClientName, new { data_val = " true ",
data_val_email = " Enter a valid email address ",
                                                data_val_required = " Please enter your name "})
        @Html.ValidationMessageFor(m => m.ClientName)
    </p>

因为-在C#中是非法变量名字符，所以用_替代，同时asp.net mvc生成html时会将它替换为-。

最后一个问题是，当客户端验证需要使用服务器端资源时，怎么办？这时就要使用到Remote Validation了。首先，自然是得后端有一个ajax调用的action了：

   public JsonResult ValidateDate( string Date)
        {
            DateTime parsedDate;
             if (!DateTime.TryParse(Date, out parsedDate))
            {
                 return Json( " Please enter a valid date (mm/dd/yyyy) ", JsonRequestBehavior.AllowGet);
            }
             else if (DateTime.Now > parsedDate)
            {
                 return Json( " Please enter a date in the future ", JsonRequestBehavior.AllowGet);
            }
             else
            {
                 return Json( true, JsonRequestBehavior.AllowGet);
            }
        }

然后，在Appointment类的Date属性上加个Remote特性：

[DataType(DataType.Date)]
         // [FutureDateValidator(ErrorMessage = "You must enter a date in the future")]
         [Remote( " ValidateDate " , " Appointment " )]
         public DateTime Date { get; set; }

至此，它就完成了。当你输入date结束后，就会调用ValidateDate(string Date)方法。我在想，这里Appointment得是真正的ViewModel了，要不然就太别扭了。因为它实际上是调用了controller的action方法了。

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