需要一些建议我正在尝试编写一个验证器,该验证器只有在下拉列表中选择特定值时才会启动。
我在这个表格上有两个下拉列表,一个是国家,另一个是美国,国家下拉列表只在从国家下拉列表中选择美国时显示。
我需要一个验证器,只有当美国被选为国家时,才能使州下拉列表成为必填字段。
作为背景信息,这是一个MVC3 Web应用程序,States下拉列表的显示/隐藏代码是JQuery。
另一种选择是将规则动态添加到jQuery中进行验证。但是,您还需要在服务器端检查此自定义逻辑。您可以在控制器中执行此操作,或者理想情况下,您的VieWModel将实现IValidateableObject,以检查country="usa"是否需要country。
使用jQuery的.rules.add和.remove:
http://docs.jquery.com/Plugins/Validation/rules#.22remove.22rules
所以你可以做一些类似的事情:
$(document).ready(function() {
$("#country").change(function(){
if($(this).val()=="usa")
{
$("#yourCountyDropDown").rules("add", {
required: true,
messages: {
required: "County is required"
}
});
}
else
{
$("#yourCountyDropDown").rules("remove");
}
});
});
和您的ViewModel
public class WhateverYourObjectNameCreateViewModel : IValidatableObject
{
#region Validation
public IEnumerable Validate(ValidationContext validationContext)
{
if (this.Country=="USA" && string.IsNullOrEmpty(this.County))
{
yield return new ValidationResult("County is required");
}
}
#endregion
}
You could write a custom validation attribute:
public class RequiredIfAttribute : ValidationAttribute
{
public RequiredIfAttribute(string otherProperty, object otherPropertyValue)
{
OtherProperty = otherProperty;
OtherPropertyValue = otherPropertyValue;
}
public string OtherProperty { get; private set; }
public object OtherPropertyValue { get; private set; }
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var property = validationContext.ObjectType.GetProperty(OtherProperty);
if (property == null)
{
return new ValidationResult(string.Format("Unknown property: {0}", OtherProperty));
}
object otherPropertyValue = property.GetValue(validationContext.ObjectInstance, null);
if (!object.Equals(OtherPropertyValue, otherPropertyValue))
{
return null;
}
if (value != null)
{
return null;
}
return new ValidationResult(this.FormatErrorMessage(validationContext.DisplayName));
}
}
现在你可以有一个视图模型:
public class MyViewModel
{
public string Country { get; set; }
[RequiredIf("Country", "usa", ErrorMessage = "Please select a state")]
public string State { get; set; }
public IEnumerable<SelectListItem> Countries
{
get
{
return new[]
{
new SelectListItem { Value = "fr", Text = "France" },
new SelectListItem { Value = "usa", Text = "United States" },
new SelectListItem { Value = "spa", Text = "Spain" },
};
}
}
public IEnumerable<SelectListItem> States
{
get
{
return new[]
{
new SelectListItem { Value = "al", Text = "Alabama" },
new SelectListItem { Value = "ak", Text = "Alaska" },
new SelectListItem { Value = "az", Text = "Arizona" },
};
}
}
}
控制器:
public class HomeController : Controller
{
public ActionResult Index()
{
var model = new MyViewModel();
return View(model);
}
[HttpPost]
public ActionResult Index(MyViewModel model)
{
return View(model);
}
}
和一个视图:
@model MyViewModel
@using (Html.BeginForm())
{
<div>
@Html.DropDownListFor(x => x.Country, Model.Countries, "-- Country --")
@Html.ValidationMessageFor(x => x.Country)
</div>
<div>
@Html.DropDownListFor(x => x.State, Model.States, "-- State --")
@Html.ValidationMessageFor(x => x.State)
</div>
<button type="submit">OK</button>
}
您可能还发现验证属性的Foolproof包非常有用。