好吧，我实现了 this guy made，它作为一个带有 Data Annotations 的 chram 工作。您确实需要做一些工作才能更改 check 以获取 下拉值，但这是我发现使用 Data Annotations 实现验证的更优雅的方式 和 不显眼。
这里是一个例子：
型号
...
[RequiredIf("IsUKResident", true, ErrorMessage = "You must specify the City if UK resident")]
public string City { get; set; }
...
自定义属性
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations;
using System.Web.Mvc;
namespace Mvc3ConditionalValidation.Validation
{
public class RequiredIfAttribute : ValidationAttribute, IClientValidatable
{
private RequiredAttribute _innerAttribute = new RequiredAttribute();
public string DependentProperty { get; set; }
public object TargetValue { get; set; }
public RequiredIfAttribute(string dependentProperty, object targetValue)
{
this.DependentProperty = dependentProperty;
this.TargetValue = targetValue;
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
// get a reference to the property this validation depends upon
var containerType = validationContext.ObjectInstance.GetType();
var field = containerType.GetProperty(this.DependentProperty);
if (field != null)
{
// get the value of the dependent property
var dependentvalue = field.GetValue(validationContext.ObjectInstance, null);
// compare the value against the target value
if ((dependentvalue == null && this.TargetValue == null) ||
(dependentvalue != null && dependentvalue.Equals(this.TargetValue)))
{
// match => means we should try validating this field
if (!_innerAttribute.IsValid(value))
// validation failed - return an error
return new ValidationResult(this.ErrorMessage, new[] { validationContext.MemberName });
}
}
return ValidationResult.Success;
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var rule = new ModelClientValidationRule()
{
ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
ValidationType = "requiredif",
};
string depProp = BuildDependentPropertyId(metadata, context as ViewContext);
// find the value on the control we depend on;
// if it's a bool, format it javascript style
// (the default is True or False!)
string targetValue = (this.TargetValue ?? "").ToString();
if (this.TargetValue.GetType() == typeof(bool))
targetValue = targetValue.ToLower();
rule.ValidationParameters.Add("dependentproperty", depProp);
rule.ValidationParameters.Add("targetvalue", targetValue);
yield return rule;
}
private string BuildDependentPropertyId(ModelMetadata metadata, ViewContext viewContext)
{
// build the ID of the property
string depProp = viewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(this.DependentProperty);
// unfortunately this will have the name of the current field appended to the beginning,
// because the TemplateInfo's context has had this fieldname appended to it. Instead, we
// want to get the context as though it was one level higher (i.e. outside the current property,
// which is the containing object (our Person), and hence the same level as the dependent property.
var thisField = metadata.PropertyName + "_";
if (depProp.StartsWith(thisField))
// strip it off again
depProp = depProp.Substring(thisField.Length);
return depProp;
}
}
}
客户端
...
<script src="@Url.Content("~/Scripts/jquery.validate.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.js")" type="text/javascript"></script>
<script>
$.validator.addMethod('requiredif',
function (value, element, parameters) {
var id = '#' + parameters['dependentproperty'];
// get the target value (as a string,
// as that's what actual value will be)
var targetvalue = parameters['targetvalue'];
targetvalue =
(targetvalue == null ? '' : targetvalue).toString();
// get the actual value of the target control
// note - this probably needs to cater for more
// control types, e.g. radios
var control = $(id);
var controltype = control.attr('type');
var actualvalue =
controltype === 'checkbox' ?
control.attr('checked').toString() :
control.val();
// if the condition is true, reuse the existing
// required field validator functionality
if (targetvalue === actualvalue)
return $.validator.methods.required.call(
this, value, element, parameters);
return true;
}
);
$.validator.unobtrusive.adapters.add(
'requiredif',
['dependentproperty', 'targetvalue'],
function (options) {
options.rules['requiredif'] = {
dependentproperty: options.params['dependentproperty'],
targetvalue: options.params['targetvalue']
};
options.messages['requiredif'] = options.message;
});
</script>
...
<div class="editor-label">
@Html.LabelFor(model => model.City)
</div>
<div class="editor-field">
@Html.EditorFor(model => model.City)
@Html.ValidationMessageFor(model => model.City)
</div>
<div class="editor-label">
@Html.LabelFor(model => model.IsUKResident)
</div>
<div class="editor-field">
@Html.EditorFor(model => model.IsUKResident)
@Html.ValidationMessageFor(model => model.IsUKResident)
</div>
...