自定义助手无法正常工作

Question

我创建了以下用于显示图像的Html Helper类：

类别：

namespace MvcWebMobile.CustomHelpers
{
    public static class CustomHelper
    {
        public static string Image(this HtmlHelper helper, string id, string url, string alternateText)
        {
            return Image(helper, id, url, alternateText, null);
        }

        public static string Image(this HtmlHelper helper, string id, string url, string alternateText, object htmlAttributes)
        {
            // Create tag builder
            var builder = new TagBuilder("img");

            // Create valid id
            builder.GenerateId(id);

            // Add attributes
            builder.MergeAttribute("src", url);
            builder.MergeAttribute("alt", alternateText);
            builder.MergeAttributes(new RouteValueDictionary(htmlAttributes));

            // Render tag
            return builder.ToString(TagRenderMode.SelfClosing);
        }
    }
}

查看：

@Html.Image("img1", "../../Content/images/icons-18-black.png", "logo")

现在，当我在视图中使用自定义帮助程序时，不显示图像，而不是在网页上打印图像跟随消息

<img alt="logo" id="img1" src="../../Content/images/icons-18-black.png" /> <img alt="logo" border="4px" id="img1" src="../../Content/images/icons-18-black.png" /> 

Answer 1

您的帮助者应该返回HtmlString而不是string。

public static HtmlString Image(this HtmlHelper helper, string id, string url, string alternateText)
{
    return Image(helper, id, url, alternateText, null);
}

public static HtmlString Image(this HtmlHelper helper, string id, string url, string alternateText, object htmlAttributes)
{
    // ...
    return new HtmlString(builder.ToString(TagRenderMode.SelfClosing));
}

Answer 2

而不是返回字符串尝试返回MvcHtmlString，

 public static MvcHtmlString Image(this HtmlHelper helper, string id, string url, string alternateText)
 {

 }

Answer 3

使用MvchtmlString：

public static MvcHtmlString Image(this HtmlHelper helper, string id, string url, string alternateText)
 {
// ...
    return new MvcHtmlString(builder.ToString(TagRenderMode.SelfClosing));
 }