select right menu on master page in MVC from child

问题:

I have a couple of list items in a shared _layout.cshtm file (master page) in my MVC application.

something like:

<ul>
    <li>Home</li>
    <li>about</li>
    <li>contact</li>
    <li>blog</li>
</ul>

when the user is in a homepage, I want home li item to have class selected, like so:

<li class="selected">Home</li>

and so on. What is the best way to do this?

In regular asp.net website, I used to have a method in master page and call that method from child page but in MVC I am not sure what to do.

thanks.

回答1:

You could write a custom helper method:

public static MvcHtmlString MenuItem(
    this HtmlHelper htmlHelper, 
    string text,
    string action, 
    string controller
)
{
    var li = new TagBuilder("li");
    var routeData = htmlHelper.ViewContext.RouteData;
    var currentAction = routeData.GetRequiredString("action");
    var currentController = routeData.GetRequiredString("controller");
    if (string.Equals(currentAction, action, StringComparison.OrdinalIgnoreCase) &&
        string.Equals(currentController, controller, StringComparison.OrdinalIgnoreCase))
    {
        li.AddCssClass("selected");
    }
    li.SetInnerText(text);
    return MvcHtmlString.Create(li.ToString());
}

and then:

<ul>
    @Html.MenuItem("Home", "home", "home")
    @Html.MenuItem("About", "about", "home")
    @Html.MenuItem("Contact", "contact", "home")
    @Html.MenuItem("Blog", "blog", "home")
</ul>

The helper check the current action and controller and if they match the one passed as arguments to the helper it appends the selected CSS class to the li.

回答2:

Just wanted to share what i do:

I create folder App_Code and add CustomHelpers.cshtml. In it i create something like this:

@helper MainMenu(string SelectedItem) {
    <ul class="MainMenu">
        <li><a href="/home" @if (SelectedItem == "Home") { <text>class="Active"</text> }>Home</a></li>
        <li><a href="/about" @if (SelectedItem == "About") { <text>class="Active"</text> }>About</a></li>
        <li><a href="/foo" @if (SelectedItem == "Foo") { <text>class="Active"</text> }>Foo</a></li>
    </ul>
}

Than in my MasterPage (_Layout.cshtml) i add this where i want my menu to apear:

@CustomHelpers.MainMenu(ViewBag.SelectedMenu)

And than in my view, just like i change my page title, i change my selected menu:

@{
    ViewBag.Title = "Welcome to my homepage";
    ViewBag.SelectedMenu = "Home";
}

Got my idea from this tutorial: www.asp.net/mvc/videos/mvc-3/mvc-3-razor-helpers