Question

Hi I would like to dynamically load meny items in the _Layout.cshtml file.

How do I do that? Can you point me to a code example doing that? Or something?

I am not looking for any particular fancy way of doing this.

Below I will describe my intention:

I just want a list of different menu items rendering in the left side of the screen. Say there is a hierarchy of menu items in the form of

Categories -> Types -> Brands -> Models.

So intially just a list of the Category menu items render, then one chooses a Category and a list of Type menu items render, one choses a Type and a list of Brand menu items render, one chooses a Brand and a list of Model menu items render, like below:

(The initial appearance of the menu)

Categories:

• Cars
• Boats
• Bikes
• Motorbikes

(Cars is chosen)

Types:

• Coupe
• Truck
• Van
• Convertible

(Coupe is chosen)

Brands:

• BMW
• Volvo
• Ford
• Mercedes

(BMW is chosen)

Model:

• 325i
• 128i
• 650i
• M6
  .

Answer 1

If you’re talking about items specific to the controller or action, you could have the action put something in ViewData that would be read by whatever view renders the menu.

Edit: A working example

The data structure: a self-referential (recursive) table with the following columns:

MenuItemId - int, primary key, identity
DisplayName - varchar
ParentMenuItemId - int, nullable, FK to MenuItemId

I then inserted the values you identified in your OP, drilling down through Cars / Coupe / BMW.

This is MVC3/Razor, along with an Entity Framework model.

Controller: (the action takes a nullable int parameter named “id”, which means that MVC will automatically route it through the standard routing handler as /Controller/Action/Id)

System.Text.StringBuilder sb = new System.Text.StringBuilder();

using (Models.StackOverflowTestEntities e = new Models.StackOverflowTestEntities())
{
    // Insert the child menu items based on the current parent
    ViewData["currentMenuItems"] = e.MenuItems.Where(i => (!id.HasValue && !i.ParentMenuItemId.HasValue) || (i.ParentMenuItemId == id)).ToList();

    // Get our breadcrumb trail
    if (id.HasValue)
    {
        int? currentItem = id;

        while (currentItem.HasValue)
        {
            var menuItem = e.MenuItems.Where(i => i.MenuItemId == currentItem).First();

            // TODO: make these into actual hyperlinks?
            sb.Insert(0, string.Format(" » {0}", menuItem.DisplayName));

            currentItem = menuItem.ParentMenuItemId;
        }
    }
}

sb.Insert(0, "Root");

ViewData["breadcrumb"] = sb.ToString();

View:

<div>@ViewData["breadcrumb"]</div>

<ul>
@{
    var menuItems = ViewData["currentMenuItems"] as IEnumerable<MvcApplication1.Models.MenuItem>;

    foreach (var menuItem in menuItems) {
        <li><a href="/Home/Index/@menuItem.MenuItemId">@menuItem.DisplayName</a></li>
    }
}
</ul>

This not only shows the appropriate list of items for the specified parent, it also shows the breadcrumb trail back to the root.