Markdown TagHelpers不呈现/显示内容

Question

我添加了一个自定义markdown taghelper，但是它不显示内容。我尝试使用不同的调整，但是以某种方式都无法解决问题。我真的不知道我做错了什么，或者缺少的部分是什么？

我希望有人会仔细检查我的代码并帮助我解决此问题，代码如下：-

namespace Web.TagHelpers
{
    [HtmlTargetElement("markdown")]
    public class MarkdownTagHelper : TagHelper
    {
        [HtmlAttributeName("markdown")]
        public ModelExpression Markdown { get; set; }
        public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
        {
            await base.ProcessAsync(context, output);

            var markdown = Markdown?.Model?.ToString() ?? "";
            var content = ConvertToMarkDown(markdown);

            output.TagName = null;
            output.Content.SetHtmlContent(content);
        }

        private string ConvertToMarkDown(string markdown)
        {
            var sanitizer = new HtmlSanitizer();
            sanitizer.RemovingAttribute += OnRemovingAttribute;

            sanitizer.AllowedTags.Remove("form");
            sanitizer.AllowedTags.Remove("button");
            sanitizer.AllowedTags.Remove("input");

            // parse the markdown to HTML
            markdown = Westwind.AspNetCore.Markdown.Markdown.Parse(markdown);

            // encode any custom tags (pasting e-mails and other markup (XML))
            // From author of HtmlSanitizer
            // https://gist.github.com/mganss/00bec2c2245c0ef86d9c82d6211def7b
            markdown = HtmlRegex.Replace(markdown, m =>
            {
                var tagName = m.Groups[1].Value;
                if (!HtmlTags.Contains(tagName))
                    return "<" + m.Value.Substring(1);
                return m.Value;
            });

            markdown = sanitizer.Sanitize(markdown);

            return markdown;
        }

        private void OnRemovingAttribute(object sender, RemovingAttributeEventArgs e)
        {
            if (!e.Attribute.Value.Contains("vbscript:", StringComparison.CurrentCultureIgnoreCase)
               && !e.Attribute.Value.Contains("javascript:", StringComparison.CurrentCultureIgnoreCase)
               && !e.Attribute.Value.Contains("data:", StringComparison.CurrentCultureIgnoreCase)
               && !e.Attribute.Name.StartsWith("on", StringComparison.CurrentCultureIgnoreCase))
            {
                // don't remove the attribute if we've deemed it safe
                e.Cancel = true;
            }
        }

        static Regex HtmlRegex = new Regex(@"</?([a-z]+[1-6]?)", RegexOptions.IgnoreCase);
        static HashSet<string> HtmlTags = new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "a", "abbr", "acronym", "address", "applet", "area", "article", "aside", "audio", "b", "base", "bdi", "bdo", "big", "blockquote", "body", "br", "button", "canvas", "caption", "center", "cite", "code", "col", "colgroup", "command", "datalist", "dd", "del", "details", "dfn", "dir", "div", "dl", "dt", "em", "embed", "fieldset", "figcaption", "figure", "font", "footer", "form", "frame", "h1", "h2", "h3", "h4", "h5", "h6", "head", "header", "hgroup", "hr", "html", "i", "iframe", "img", "input", "ins", "isindex", "kbd", "keygen", "label", "legend", "li", "link", "map", "mark", "menu", "meta", "meter", "nav", "noscript", "object", "ol", "optgroup", "option", "output", "p", "param", "pre", "progress", "q", "rp", "rt", "ruby", "s", "samp", "script", "section", "select", "small", "source", "span", "strike", "strong", "style", "sub", "summary", "sup", "table", "tbody", "td", "textarea", "tfoot", "th", "thead", "time", "title", "tr", "track", "tt", "u", "ul", "var", "video", "wbr" };
    }

我有以下剃须刀页面来显示内容：

@model IEnumerable<Post>


@{
    ViewData["Title"] = "My Posts";

}


<p class="heading">Recent Technology Posts</p>

<div class="container-post">

    <div class="row">
        @foreach (var p in Model)
        {
            <div class="col-md-6 container-column">
                <div class="item-group">
                    <div class="item one">
                        <a href="@Url.Action("GetPostBySlug", "Post", new {slug = p.Slug })">@p.Topic</a>
                    </div>
                    <div class="item two">
                        <p class="fa fa-thumb-tack"></p><span>Posted On:</span>
                        <i class="fa fa-calendar"></i>
                        <i class="timeStampValue" data-value="@p.Published"></i>
                        <i class="fa fa-user"></i><span>Post By: Author Name</span>
                    </div>
                    <hr />
                    <div class="item three">                       
                       <markdown markdown="@p.Content" />                     

                    </div>
                    <div class="readMore">
                        <span class="btn btn-outline-primary">ReadMore..</span>
                    </div>
                </div>
            </div>
        }

    </div>
</div>

启动类：-

namespace Web
{
    public class Startup
    {
        private IConfiguration Config { get; }

        public Startup(IConfiguration configuration)
        {
            Config = configuration;
        }
        public void ConfigureServices(IServiceCollection services)
        {
            services.ConfigureDatabase(Config);
            services.AddScoped(typeof(IAsyncRepository<>), typeof(PostRepository<>));
            services.AddMvc();
            services.AddHttpContextAccessor();
            services.AddMarkdown();

        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, PostContext context)
        {
            context.Database.EnsureCreated();
            app.UseHttpsRedirection();
            app.UseMarkdown();
            app.UseStaticFiles();
            app.UseRouting(env);

        }
    }

_ViewImports文件：

@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
@addTagHelper *, NWebsec.AspNetCore.Mvc.TagHelpers
@addTagHelper *, Web

控制器：-

   public async Task<IActionResult> GetAllPosts()
        {
            var result = await _repository.GetAllPosts();
            return View(result);
        }