css - ASP.NET MVC - style list item based on controller

Question

My ultimate goal is to have a menu that adds a class to the list item that associates with the current page I am on.

So I have it set up such that each controller will be associated with an item in my menu. I need to add a class to that list item (changing the color, background, whatever).

Is there a simple way to do this? Pass a value to the View, then what?

Answer 1

In a recent project of mine I did it using HtmlHelper extensions and getting data from the ViewContext.RouteData.Values collection.

So building off a simple extension like this:

public static string OnClass(this HtmlHelper html, bool isOn)
{
    if (isOn)
        return " class="on"";

    return string.Empty;
}

You can build up any number of combinations, e.g.

Just testing the current action:

public static string OnClass(this HtmlHelper html, string action)
{
    string currentAction = html.ViewContext.RouteData.Values["action"].ToString();

    return html.OnClass(currentAction.ToLower() == action.ToLower());
}

Testing for a number of actions:

public static string OnClass(this HtmlHelper html, string[] actions)
{
    string currentAction = html.ViewContext.RouteData.Values["action"].ToString();

    foreach (string action in actions)
    {
        if (currentAction.ToLower() == action.ToLower())
            return html.OnClass(true);
    }

    return string.Empty;
}

Testing for action and controller:

public static string OnClass(this HtmlHelper html, string action, string controller)
{
    string currentController = html.ViewContext.RouteData.Values["controller"].ToString();

    if (currentController.ToLower() == controller.ToLower())
        return html.OnClass(action);

    return string.Empty;
}

Etc, etc.

Then you simply call it in your view(s) like so

<ul id="left-menu">
    <!-- simple boolean -->
    <li <%= Html.OnClass(something == somethingElse) %>>Blah</li>
    <!-- action -->
    <li <%= Html.OnClass("Index") %>>Blah</li>
    <!-- any number of actions -->
    <li <%= Html.OnClass(new string[] { "Index", "Details", "View" }) %>>Blah</li>
    <!-- action and controller -->
    <li <%= Html.OnClass("Index", "Home") %>>Blah</li>
</ul>

Which ever way you look at it, HtmlHelper extensions are your friend! :-)

HTHs
Charles