如何扩展MVC3标签和LabelFor HTML助手？

Question

Html.Label和Html.LabelFor帮助程序方法不像大多数其他帮助程序那样支持htmlAttributes参数。但是我想设置class。事情是这样的：

Html.LabelFor(model => model.Name, new { @class = "control-label" }) 

是否有扩展标签/ LabelFor 没有诉诸复制和扩大这些方法的ILSpy DISASM输出的容易方式？

Answer 1

，您可以轻松创建自己的LabelFor延长标签：

像这样的东西应该做的，你需要

public static MvcHtmlString LabelFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, object htmlAttributes) 
{ 
    return LabelFor(html, expression, new RouteValueDictionary(htmlAttributes)); 
} 

public static MvcHtmlString LabelFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, IDictionary<string, object> htmlAttributes) 
{ 
    ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, html.ViewData); 
    string htmlFieldName = ExpressionHelper.GetExpressionText(expression); 
    string labelText = metadata.DisplayName ?? metadata.PropertyName ?? htmlFieldName.Split('.').Last(); 
    if (String.IsNullOrEmpty(labelText)) 
    { 
    return MvcHtmlString.Empty; 
    } 

    TagBuilder tag = new TagBuilder("label"); 
    tag.MergeAttributes(htmlAttributes); 
    tag.Attributes.Add("for", html.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldId(htmlFieldName)); 
    tag.SetInnerText(labelText); 
    return MvcHtmlString.Create(tag.ToString(TagRenderMode.Normal)); 
} 

更新 在使用时只需在你的项目中创建的扩展方法是什么，将此行加入您的Views\web.config

<pages> 
    <namespaces> 
    <add namespace="System.Web.Helpers" /> 
    <add namespace="System.Web.Mvc" /> 
    <add namespace="System.Web.Mvc.Ajax" /> 
    <add namespace="System.Web.Mvc.Html" /> 
    <add namespace="System.Web.Routing" /> 
    <add namespace="System.Web.WebPages" /> 
    <add namespace="MyProject.Helpers" /> <-- my extension 

    ... 

</namespaces> 
</pages> 

Answer 2

public static class LabelExtensions 
{ 
    public static IHtmlString LabelFor<TModel, TProperty>(
     this HtmlHelper<TModel> htmlHelper, 
     Expression<Func<TModel, TProperty>> expression, 
     string labelText, 
     object htmlAttributes 
    ) 
    { 
     var metadata = ModelMetadata.FromLambdaExpression<TModel, TProperty>(expression, htmlHelper.ViewData); 
     var htmlFieldName = ExpressionHelper.GetExpressionText(expression); 
     return LabelHelper(htmlHelper, metadata, htmlFieldName, labelText, htmlAttributes); 
    } 

    public static IHtmlString Label(this HtmlHelper htmlHelper, string expression, string labelText, object htmlAttributes) 
    { 
     var metadata = ModelMetadata.FromStringExpression(expression, htmlHelper.ViewData); 
     return LabelHelper(htmlHelper, metadata, expression, labelText, htmlAttributes); 
    } 

    private static IHtmlString LabelHelper(HtmlHelper html, ModelMetadata metadata, string htmlFieldName, string labelText, object htmlAttributes) 
    { 
     string str = labelText ?? (metadata.DisplayName ?? (metadata.PropertyName ?? htmlFieldName.Split(new char[] { '.' }).Last<string>())); 
     if (string.IsNullOrEmpty(str)) 
     { 
      return MvcHtmlString.Empty; 
     } 
     TagBuilder tagBuilder = new TagBuilder("label"); 
     tagBuilder.Attributes.Add("for", TagBuilder.CreateSanitizedId(html.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(htmlFieldName))); 
     var attributes = new RouteValueDictionary(htmlAttributes); 
     tagBuilder.MergeAttributes(attributes); 
     tagBuilder.SetInnerText(str); 
     return new HtmlString(tagBuilder.ToString(TagRenderMode.Normal)); 
    } 
} 

然后：

@Html.LabelFor(x => x.SomeProperty, null, new { @class = "foo" }) 

或：

@Html.Label("SomeProperty", null, new { @class = "foo" })