任何不必追溯生成这些数据属性的方法

Question

这个Html.DropDownListFor帮助程序应该生成data-属性，但如果有任何嵌套，则无法生成。所以这无法产生它们：

@( 
 Html.DropDownListFor( 
  m => m.P[0].CId, 
  new SelectList(
   Model.Cs.Values, 
   "Id", "DisplayFields", Model.Cs.StartValue), 
  Model.Cs.Message 
 ) 
)

但是，这会产生它们：

@( 
 Html.DropDownListFor( 
  m => m.CId, 
  new SelectList(
   Model.Cs.Values, 
   "Id", "DisplayFields", Model.Cs.StartValue), 
  Model.Cs.Message 
 ) 
)

如何避免返回并使用某些脚本手动定义缺少的数据属性？

Answer 1

在使用@Html.DropDownListFor帮助程序时，除了追溯分配这些缺失的数据属性外，别无他法。要保留的重要内容是data-val = "true"、data-val-required="This value is required"。此外，使用 data-valmsg-replace="true" 、 data-valmsg-for="ID OF SELECT ELEMENT" class="field-validation-valid" 进行验证的跨度。

但是，如果选择使用自定义帮助程序，则可以避免这种情况。这可以在这里看到：http://forums.asp.net/t/1649193.aspx/1/10 答案详细说明如何扩展DropDownListFor helper。这是他们使用的代码：

[SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")]
    public static MvcHtmlString DdUovFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList)
    {
        return DdUovFor(htmlHelper, expression, selectList, null /* optionLabel */, null /* htmlAttributes */);
    }

    [SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")]
    public static MvcHtmlString DdUovFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, object htmlAttributes)
    {
        return DdUovFor(htmlHelper, expression, selectList, null /* optionLabel */, new RouteValueDictionary(htmlAttributes));
    }

    [SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")]
    public static MvcHtmlString DdUovFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, IDictionary<string, object> htmlAttributes)
    {
        return DdUovFor(htmlHelper, expression, selectList, null /* optionLabel */, htmlAttributes);
    }

    [SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")]
    public static MvcHtmlString DdUovFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel)
    {
        return DdUovFor(htmlHelper, expression, selectList, optionLabel, null /* htmlAttributes */);
    }

    [SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")]
    public static MvcHtmlString DdUovFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel, object htmlAttributes)
    {
        return DdUovFor(htmlHelper, expression, selectList, optionLabel, new RouteValueDictionary(htmlAttributes));
    }

    [SuppressMessage("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters", Justification = "Users cannot use anonymous methods with the LambdaExpression type")]
    [SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")]
    public static MvcHtmlString DdUovFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel, IDictionary<string, object> htmlAttributes)
    {
        if (expression == null)
        {
            throw new ArgumentNullException("expression");
        }

        ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);

        IDictionary<string, object> validationAttributes = htmlHelper
            .GetUnobtrusiveValidationAttributes(ExpressionHelper.GetExpressionText(expression), metadata);

        if (htmlAttributes == null)
            htmlAttributes = validationAttributes;
        else
            htmlAttributes = htmlAttributes.Concat(validationAttributes).ToDictionary(k => k.Key, v => v.Value);

        return SelectExtensions.DropDownListFor(htmlHelper, expression, selectList, optionLabel, htmlAttributes);
    }