How to extend the ValidationSummary HTML Helper in ASP.NET MVC?

I had to extend the validation summary extensions in another project of mine to deal with more than one form on a page.

Although this is different, you could create your own extension method...

namespace System.Web.Mvc
{
    public static class ViewExtensions
    {
        public static string MyValidationSummary(this HtmlHelper html, string validationMessage)
        {
            if (!html.ViewData.ModelState.IsValid)
            {
                return "<div class=\"validation-summary\">" + html.ValidationSummary(validationMessage) + "</div>"
            }

            return "";
        }
    }
}

Then just call

<%= Html.MyValidationSummary(
    "Login was unsuccessful. Please correct the errors and try again.") %>

HTHs, Charles

What you can do is this :

<%if (!ViewData.ModelState.IsValid) { %>
<div class="validation-summary"> 
    <%= Html.ValidationSummary(
        "Login was unsuccessful. Please correct the errors and try again.") %>
</div>
<% } %>

For MVC 2, ValidationSummary is a extension method, you must add

using System.Web.Mvc.Html;

Use this CSS for li tag for example...

.validation-summary-errors ul li {color:Red;}