Customize ValidationSummary in ASP.NET MVC 2

Question

I want to customize the html output of ValidationSummary in ASP.NET MVC 2

from

<div class="validation-summary-errors">
    <span>Oops! validation was failed because:</span>
    <ul>
        <li>The Title field is required.</li>
        <li>The Body field is required.</li>
    </ul>
</div>

to

<div class="validation-error">
    <p>Oops! validation was failed because:</p>
    <ul>
        <li>The Title field is required.</li>
        <li>The Body field is required.</li>
    </ul>
</div>

Is there any new way in asp.net MVC 2 to solve this?

Answer 1

There doesn't seem to be any way to do it with templating, which is pretty poor. If you take a look at the code for this particular helper method you'll see the HTML is baked into the method itself:

public static string ValidationSummary(this HtmlHelper htmlHelper, string message, IDictionary<string, object> htmlAttributes) {
    // Nothing to do if there aren't any errors
    if (htmlHelper.ViewData.ModelState.IsValid) {
        return null;
    }

    string messageSpan;
    if (!String.IsNullOrEmpty(message)) {
        TagBuilder spanTag = new TagBuilder("span");
        spanTag.MergeAttributes(htmlAttributes);
        spanTag.MergeAttribute("class", HtmlHelper.ValidationSummaryCssClassName);
        spanTag.SetInnerText(message);
        messageSpan = spanTag.ToString(TagRenderMode.Normal) + Environment.NewLine;
    }
    else {
        messageSpan = null;
    }

    StringBuilder htmlSummary = new StringBuilder();
    TagBuilder unorderedList = new TagBuilder("ul");
    unorderedList.MergeAttributes(htmlAttributes);
    unorderedList.MergeAttribute("class", HtmlHelper.ValidationSummaryCssClassName);

    foreach (ModelState modelState in htmlHelper.ViewData.ModelState.Values) {
        foreach (ModelError modelError in modelState.Errors) {
            string errorText = GetUserErrorMessageOrDefault(htmlHelper.ViewContext.HttpContext, modelError, null /* modelState */);
            if (!String.IsNullOrEmpty(errorText)) {
                TagBuilder listItem = new TagBuilder("li");
                listItem.SetInnerText(errorText);
                htmlSummary.AppendLine(listItem.ToString(TagRenderMode.Normal));
            }
        }
    }
}

The good news is, with MVC being open source, you can go and grab the source from the CodePlex repository and tweak it any way you like.