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，列表中的第一项有一个空值.如果我没有选择列表中的任何内容，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了该字段.

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;
        }
    }

有什么想法吗?我错过了什么吗?

any ideas? am I missing something?

推荐答案

它看起来像是一个合法的错误，这是我在搜索中找到的最佳解决方法:

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

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

简而言之.您将问题的根源 DropDownListFor 包装在自定义 Html 扩展中，然后手动检索不显眼的客户端验证规则，如下所示:

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
    );

然后，您将 validationAttributes 字典与传递给自定义助手的任何其他 html 属性结合起来，然后将其传递给 DropDownListFor

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

我使用的完整代码(我也有一个标签，你可以随意解耦):

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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