ASP.NET Core should not encode attribute value in TagBuilder when rendering Json+Ld script

Question

I wrote an HtmlHelper extension to render Json+Ld script tags. The reason why I ask you for help is, the type attribute value "application/ld+json" is encoded and looks like "application/ld+json" and I could found a solution.

My C# code of the HtmlHelper:

    public static IHtmlContent GetJsonLdScriptTag(this IHtmlHelper helper, string innerText)
    {
        //if(string.IsNullOrEmpty(innerText))
        //    return HtmlString.Empty;

        var tag = new TagBuilder("script");
        tag.MergeAttribute("type", "application/ld+json");

        tag.InnerHtml.AppendHtml(innerText);
        tag.TagRenderMode = TagRenderMode.Normal;

        return tag;
    }

In my view I use call the Html extension so:

    @Html.GetJsonLdScriptTag("")

Html output is:

<script type="application/ld&#x2B;json"></script>

I tried to decode by using HtmlDecode(...) and with returning Html.Raw(...) ;, but without success.

Another try was to return string instead IHtmlContent object, but this failed also.

    public static string GetJsonLdScriptTag(this IHtmlHelper helper, string innerText)
    {
        //if(string.IsNullOrEmpty(innerText))
        //    return HtmlString.Empty;

        var tag = new TagBuilder("script");
        tag.MergeAttribute("type", "application/ld+json");

        tag.InnerHtml.AppendHtml(innerText);
        tag.TagRenderMode = TagRenderMode.Normal;

        return tag.ToHtmlString();
    }

    public static string ToHtmlString(this IHtmlContent content)
    {
        using var writer = new IO.StringWriter();
        content.WriteTo(writer, HtmlEncoder.Default);
        return writer.ToString();
    }

Do you have an idea to handle this issue without hacks?

Best Tino

Answer 1

Looking at the source code , there doesn't seem to be any way to disable the encoding for an attribute value. It might be worth logging an issue to see if this could be added; but for the short term, you'll need to use something other than the TagBuilder class.

private sealed class JsonLdScriptTag : IHtmlContent
{
    private readonly string _innerText;
    
    public JsonLdScriptTag(string innerText)
    {
        _innerText = innerText;
    }
    
    public void WriteTo(TextWriter writer, HtmlEncoder encoder)
    {
        writer.Write(@"<script type=""application/ld+json"">");
        writer.Write(_innerText);
        writer.Write("</script>");
    }
}

public static IHtmlContent GetJsonLdScriptTag(this IHtmlHelper helper, string innerText)
    => new JsonLdScriptTag(innerText);