如何从MY OWN HtmlHelper中访问HtmlHelper方法？

Question

我正在为ASP.NET MVC编写自己的HtmlHelper扩展:

public static string CreateDialogLink (this HtmlHelper htmlHelper, string linkText, 
                                      string contentPath)
        {
            // fix up content path if the user supplied a path beginning with '~'
            contentPath = Url.Content(contentPath);  // doesn't work (see below for why)

            // create the link and return it
            // .....
        };

当我遇到麻烦的是试着访问UrlHelper从内我的HtmlHelper的定义.问题是您通常访问HtmlHelper(via Html.MethodName(...) )的方式是通过View上的属性.我自己的扩展课程显然无法使用此功能.

这是ViewMasterPage(从Beta开始)的实际MVC源代码- 定义Html和Url.

public class ViewMasterPage : MasterPage
    {
        public ViewMasterPage();

        public AjaxHelper Ajax { get; }
        public HtmlHelper Html { get; }
        public object Model { get; }
        public TempDataDictionary TempData { get; }
        public UrlHelper Url { get; }
        public ViewContext ViewContext { get; }
        public ViewDataDictionary ViewData { get; }
        public HtmlTextWriter Writer { get; }
    }

我希望能够在HtmlHelper中访问这些属性.

我想出的最好的是(在CreateDialogLink方法开头插入)

HtmlHelper Html = new HtmlHelper(htmlHelper.ViewContext, htmlHelper.ViewDataContainer);
UrlHelper Url = new UrlHelper(htmlHelper.ViewContext.RequestContext);

我错过了访问现有HtmlHelper和UrlHelper实例的其他方式- 或者我真的需要创建一个新方法吗？我确信没有太多开销,但如果可以,我宁愿使用已有的那些.

Answer 1

在问这个问题之前我曾经看过一些MVC源代码,但显然我错过了这个,这就是他们为Image helper做的.

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", MessageId = "1#", Justification = "The return value is not a regular URL since it may contain ~/ ASP.NET-specific characters")]
        public static string Image(this HtmlHelper helper, string imageRelativeUrl, string alt, IDictionary<string, object> htmlAttributes) {
            if (String.IsNullOrEmpty(imageRelativeUrl)) {
                throw new ArgumentException(MvcResources.Common_NullOrEmpty, "imageRelativeUrl");
            }

            UrlHelper url = new UrlHelper(helper.ViewContext);
            string imageUrl = url.Content(imageRelativeUrl);
            return Image(imageUrl, alt, htmlAttributes).ToString(TagRenderMode.SelfClosing);
        }

看起来像实例化一个新UrlHelper的毕竟是正确的方法.这对我来说足够好了.

更新:ASP.NET MVC v1.0源代码中的 RTM代码略有不同,如注释中所述.

文件:MVC\src\MvcFutures\Mvc\ImageExtensions.cs

 [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1054:UriParametersShouldNotBeStrings", MessageId = "1#", Justification = "The return value is not a regular URL since it may contain ~/ ASP.NET-specific characters")]
        public static string Image(this HtmlHelper helper, string imageRelativeUrl, string alt, IDictionary<string, object> htmlAttributes) {
            if (String.IsNullOrEmpty(imageRelativeUrl)) {
                throw new ArgumentException(MvcResources.Common_NullOrEmpty, "imageRelativeUrl");
            }

            UrlHelper url = new UrlHelper(helper.ViewContext.RequestContext);
            string imageUrl = url.Content(imageRelativeUrl);
            return Image(imageUrl, alt, htmlAttributes).ToString(TagRenderMode.SelfClosing);
        }