Question

我正在尝试编写一个自定义验证属性，该属性将有条件地要求基于模型的布尔属性的字段。

我的属性实现了IClientValidatable。我有要检查的属性的名称，但我不知道如何获取目标属性的客户端ID。

public IEnumerable<ModelClientValidationRule> 
                        GetClientValidationRules(ModelMetadata metadata, 
                                                 ControllerContext context)
{
    var clientTarget = ?????;
    var rule = new ModelClientValidationRule()
    {
        ErrorMessage = 
            FormatErrorMessage(metadata.DisplayName ?? metadata.PropertyName),
        ValidationType = "requiredif"
    };

    rule.ValidationParameters["target"] = clientTarget;

    yield return rule;
}

javascript：

$.validator.addMethod("requiredif", function (value, element, target)
{
    //check on value of target
});

$.validator.unobtrusive.adapters.addSingleVal("requiredif", "target");

如何获取目标属性的客户端ID，以便客户端javascript可以检查值？

Answer 1

我接受了Nathan的优秀答案，添加了一些注释，并将其包装在名为GetHtmlId的扩展方法中，现在我可以使用这样的代码来获取同一页面上任何其他元素的HTML ID：

    public virtual IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        var rule = new ModelClientValidationRule {
            ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
            ValidationType = "requiredif",
        };

        // Find the value on the control we depend on...
        string depProp = this.GetHtmlId(metadata, context, this.DependentPropertyName);

        rule.ValidationParameters.Add("dependentproperty", depProp);

        yield return rule;
    }

这是扩展方法：

using System;
using System.Collections.Generic;
using System.Web.Mvc;

namespace sbs.Lib.Web.ValidationAttributes
{
    public static class IClientValidatableExtensions
    {
        /// <summary> Returns the HTML ID of the specified view model property. </summary>
        /// <remarks> Based on: http://stackoverflow.com/a/21018963/1637105 </remarks>
        /// <param name="metadata"> The model metadata. </param>
        /// <param name="viewContext"> The view context. </param>
        /// <param name="propertyName"> The name of the view model property whose HTML ID is to be returned. </param>
        public static string GetHtmlId(this IClientValidatable me,
                                       ModelMetadata metadata, ControllerContext context,
                                       string propertyName)
        {
            var viewContext = context as ViewContext;

            if (viewContext == null || viewContext.ViewData.TemplateInfo.HtmlFieldPrefix == string.Empty) {
                return propertyName;
            } else {
                // This is tricky.  The "Field ID" returned by GetFullHtmlFieldId is the HTML ID
                // attribute created by the MVC view engine for the property whose validator is
                // being set up by the caller of this routine. This code removes the property
                // name from the Field ID, then inserts the specified property name.
                // Of course, this only works for elements on the same page as the caller of
                // this routine!
                string fieldId = viewContext.ViewData.TemplateInfo.GetFullHtmlFieldId("");
                fieldId = fieldId.Remove(fieldId.LastIndexOf("_"));
                return fieldId + "_" + propertyName;
            }
        }
    }
}

Answer 2

这只是用MVC5测试的，但我怀疑它没有从MVC3改变。

这有点难看，但似乎有效。有两个假设：

MVC框架实际上总是传递ViewContext ControllerContext的{{1}}参数。在我的所有测试中都是如此，但我无法保证这100％。
另一个属性位于相同的模型类级别（例如，不是复杂类型的子属性）

如果这两个假设都成立，则以下似乎有效：

GetClientValidationRules(....)

Answer 3

这对我有用，可能需要一些调整，但你可以得到这个想法：

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 != null && 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)
{
    return QualifyFieldId(metadata, this.DependentProperty, viewContext);
}

属性属性如：

[RequiredIf("SelectedPeriod", "DateRange", ErrorMessageResourceName = "FromDateRequired", ErrorMessageResourceType = typeof(Common))]
public DateTime? StartDate { get; set; }
//dependent property
public string SelectedPeriod { get; set; }

这就是如何获得字段ID：

protected string QualifyFieldId(ModelMetadata metadata, string fieldId, ViewContext viewContext)
{
    // build the ID of the property
    string depProp = viewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(fieldId);

    var thisField = metadata.PropertyName + "_";
    if (depProp.StartsWith(thisField))
    // strip it off again
    depProp = depProp.Substring(thisField.Length);
else if (null != metadata.ContainerType && !string.IsNullOrEmpty(metadata.ContainerType.Name))
    {
        depProp = metadata.ContainerType.Name + "_" + fieldId;
    }
    return depProp;
}

Answer 4

看看这个article。它讨论了服务器端的DataAnnotation验证，它还演示了如何通过实现IClientVaildatable并在客户端编写一些jquery来在客户端挂钩这些属性。

如何获取模型属性的id以与MVC3中的自定义IClientValidatable一起使用

4 个答案: