Building HtmlStrings in ASP.NET MVC

Question

I have an extension method that needs to return an HtmlString. The method has a loop which will build the HtmlString, however the HtmlString object has no Append method and does not allow concatenation using the + operator so I am not sure how I would build the HtmlString.

I'd like to use the StringBuilder but it doesn't have a ToHtmlString method...

Any solutions or patterns for this?

I think you should be able to build a normal stringbuilder with the HTML content and then output it wrapped in an @Html.Raw() call, would this solve the problem? — dougajmcdonald, Oct 26 '11 at 12:44
Thanks - that worked great. Will draft an answer with code for this solution. — Judo, Oct 26 '11 at 12:52
No problem, glad it helped, no point re-inventing the wheel if there's a helper for it! :) — dougajmcdonald, Oct 26 '11 at 14:45
I prefer the answer by @swapneel as it leaves the door open for adding a RouteValueDictionary parameter to your extension method and have the relevent tag rendered in a MVC'y way. This applies whether you are rendering a single tag or a whole block of HTML. — Daniel Dyson, Oct 26 '11 at 16:51
I am not sure if I get this right so I won't post it as an answer, but how about using your StringBuilder but adding an extension method to StringBuilder ToHtmlString? — Demetris Leptos, Feb 27 '16 at 10:02

score 34 · Answer 1 · edited Jan 04 '23 at 22:14

34

Why not just build the string in a stringbuilder and then

return MvcHtmlString.Create(sb.ToString());

edited Jan 04 '23 at 22:14

KyleMit

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answered Oct 26 '11 at 12:58

Tetaxa

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score 12 · Accepted Answer · edited Jan 04 '23 at 21:07

I think you want to use TagBuilder. See also Using the TagBuilder Class to Build HTML Helpers like this:

// 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);

score 1 · Answer 3 · edited May 23 '17 at 12:09

1

You could have a look at the fubu spin-off for creating HTML Tags. Here is a SO question that talks a bit about its usage.

edited May 23 '17 at 12:09

Community

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answered Oct 26 '11 at 12:46

flq

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score 1 · Answer 4 · answered Oct 26 '11 at 12:47

1

You could write the ToHtmlString() method yourself as a extension method on StringBuilder.

answered Oct 26 '11 at 12:47

Mattias Jakobsson

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score 0 · Answer 5 · edited Jan 04 '23 at 21:09

0

There are several solutions to this including using the TagBuilder, but using Html.Raw() worked very well for me:

public static IHtmlString HtmlMethod(this HtmlHelper htmlhelper, Object object)
{
    var sb = new StringBuilder();
    foreach (var item in object)
    {
        sb.Append(object.outputStr)
    }
    return htmlHelper.Raw(sb.ToString());
}

edited Jan 04 '23 at 21:09

KyleMit

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answered Oct 26 '11 at 12:57

Judo

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Building HtmlStrings in ASP.NET MVC

5 Answers5