ASP.Net MVC 3不显眼的客户端验证不适用于下拉列表 [英] ASP.Net MVC 3 unobtrusive client validation does not work with drop down lists

问题描述

我有一个简单的下拉列表，列表中的第一个项目有一个空值。如果我没有在列表中选择任何东西，客户端验证将忽略它。我使用注释属性在模型上根据需要设置该字段。

  @ Html.DropDownListFor（model => Model。 CCPayment.State，UnitedStatesStates.StateSelectList）
 
 
 
 [必需（ErrorMessage =状态为必需。）] 
 public string State 
 {
 get 
 {
 return _state; 
} 
 set 
 {
 _state = value; 
} 
} 
  

任何想法？我是否缺少某些东西？

解决方案

它看起来像一个合法的错误，这是我在搜索中找到的最好的解决方法： / p>

http://forums.asp.net /t/1649193.aspx

简而言之。您可以在自定义的Html扩展名中包含问题的来源 DropDownListFor ，并手动检索不引人注目的客户端验证规则，如下所示：

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

然后，您将 validationAttributes 字典与任何其他html属性传递到您的自定义帮助器，并将其传递到 DropDownListFor

我完整的代码使用（我也有一个标签，你可以随意脱离）：

  public static IHtmlString DropDownListWithLabelFor< TModel ，TProperty>（此HtmlHelper< TModel>帮助器，表达式，字符串标签，IEnumerable< SelectListItem>项，字符串blankOption，对象htmlAttributes = null）
 {
 var l = new TagBuilder（label）; 
 var br = new TagBuilder（br）; 
 
 var metadata = ModelMetadata.FromLambdaExpression（expression，helper.ViewData）; 
 var mergedAttributes = helper.GetUnobtrusiveValidationAttributes（ExpressionHelper.GetExpressionText（expression），metadata）; 
 
 if（htmlAttributes！= null）
 {
 foreach（TypeDescriptor.GetProperties（htmlAttributes）中的PropertyDescriptor描述符）
 {
对象值=描述符。的GetValue（htmlAttributes）; 
 mergedAttributes.Add（descriptor.Name，value）; 
} 
} 
 
 l.InnerHtml = label + br.ToString（TagRenderMode.SelfClosing）+ helper.DropDownListFor（expression，items，blankOption，mergedAttributes）; 
 return MvcHtmlString.Create（l.ToString（TagRenderMode.Normal））; 
} 
  

I have a simple drop down list, the first item in the list has an empty value. If I do not select anything in the list the client validation ignores it. I have that field set up as required on the model using annotation attributes.

 @Html.DropDownListFor(model => Model.CCPayment.State, UnitedStatesStates.StateSelectList)



[Required(ErrorMessage = "State is Required.")]
    public string State
    {
        get
        {
            return _state;
        }
        set
        {
            _state = value;
        }
    }

any ideas? am I missing something?

解决方案

It looks like a legitimate bug, here's the best workaround I've found in my search:

http://forums.asp.net/t/1649193.aspx

In short. You wrap the source of the problem, DropDownListFor, in a custom Html extension and you manually retrieve the unobtrusive clientside validation rules like this:

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

Then you combine your validationAttributes dictionary with any other html attributes passed into your custom helper and you pass that along to DropDownListFor

The complete code that I'm using (I have a label in there too, you can feel free to de-couple):

public static IHtmlString DropDownListWithLabelFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression, string label, IEnumerable<SelectListItem> items, string blankOption, object htmlAttributes = null)
{
    var l = new TagBuilder("label");
    var br = new TagBuilder("br");

    var metadata = ModelMetadata.FromLambdaExpression(expression, helper.ViewData);
    var mergedAttributes = helper.GetUnobtrusiveValidationAttributes(ExpressionHelper.GetExpressionText(expression), metadata);

    if (htmlAttributes != null)
    {
        foreach (PropertyDescriptor descriptor in TypeDescriptor.GetProperties(htmlAttributes))
        {
            object value = descriptor.GetValue(htmlAttributes);
            mergedAttributes.Add(descriptor.Name, value);
        }
    }

    l.InnerHtml = label + br.ToString(TagRenderMode.SelfClosing) + helper.DropDownListFor(expression, items, blankOption, mergedAttributes);
    return MvcHtmlString.Create(l.ToString(TagRenderMode.Normal));
}

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