Joe Audette Joe Audette - 2 months ago 54
C# Question

TagBuilder InnerHtml in ASP.NET 5 MVC 6

It seems to me that there are major breaking changes in TagBuilder as of beta7 with no mention about them in the announcements repo.

Specifically .ToString no longer renders the tagbuilder, it just returns the name of the type.
previously we could do things like this inside our HtmlHelper extensions to build up nested html elements:

var li = new TagBuilder("li");
li.AddCssClass("inactive");
var span = new TagBuilder("span");
span.SetInnerText(somestring);
li.InnerHtml = span.ToString();


.InnerHtml now no longer accepts string because it is now IHtmlContent

but since .ToString() doesn't render the tag this doesn't work either:

li.InnerHtml = new HtmlString(span.ToString())


it merely renders as "Microsoft.AspNet.Mvc.Rendering.TagBuilder", the name of the type.

I don't see any new methods on TagBuilder to provide the needed functionality.
What am I missing? How can I build complex nested html with TagBuilder now?

Answer

Because TagBuilder now implements IHtmlContent, you should be able to use it directly, without doing .ToString().

var li = new TagBuilder("li");
li.AddCssClass("inactive");
var span = new TagBuilder("span");
span.SetInnerText(somestring);
li.InnerHtml = span;

The real problem with the current implementation in Beta 7 is that there is no easy way to append two child tag builder contents to a parent one. You can follow the discussion on GitHub.

The current proposal is to make InnerHtml not assignable, but support Append instead. This is targeted to be implemented in Beta 8.

The workaround in Beta 7 is to call parent.WriteTo with a StringWriter to convert it to a string.

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