Create a new project and add the following code in the Boot class to create the SiteMap:

Val isAdmin_? = If(() => {
  S.param("admin").flatMap(asBoolean).openOr(false)
  }, () => RedirectWithState("/", MessageState(
  "Authorized personnel only" -> NoticeType.Warning))
)
val entries = List(
  Menu.i("Home") / "index" >> LocGroup("content"), // the simple way to declare a menu

  Menu("Admin") / "admin" >> Hidden
  submenus(
    Menu(Loc("List", List("list"), "List Contacts", isAdmin_?, LocGroup("admin"))),
    Menu(Loc("Create", List("create"), "Create Contact", isAdmin_?, LocGroup("admin"))),
    Menu(Loc("Edit", List("edit"), "Edit Contact", isAdmin_?, LocGroup("admin"))),
    Menu(Loc("Delete", List("delete"), "Delete Contact", isAdmin_?, LocGroup("admin"))),
    Menu(Loc("View", List("view"), "View Contact", isAdmin_?, LocGroup("admin")))
  ),
  Menu("Search") / "search" >> LocGroup("content"),
  Menu("Contact Us") / "contact" >> LocGroup("footer"),
  Menu("About Us") / "about" >> LocGroup("footer"),

  // more complex because this menu allows anything in the
  // /static path to be visible
  Menu(Loc("Static", Link(List("static"), true, "/static/index"),
"Static Content", LocGroup("content"))))

Rendering a menu dynamically can be done by following these steps:

I'll start with the Scala code because it will be easier to first understand what this code does before trying to understand the HTML code. In fact, once you grasp how the SiteMap was built and how it works, the HTML code becomes pretty simple.

If you pay attention to the code, you'll see that we are creating a list of menu items, just like we discussed earlier, but this code is different from the previous one as it uses LocGroup and hidden, and has a submenu. The former can be used to place together menu items in logical groups, while the latter creates hierarchical menu structures, like the one appearing in the following screenshot:

We used the hidden property to prevent the menu from being shown on the page when the MenuBuilder snippet gets invoked. The submenu is shown only for users who are administrators. We did this by invoking the isAdmin_? function. This function evaluates the admin parameter and returns true or false depending upon the value of the parameter which could either be true or false. If the function returns true, the menu item will be both visible and accessible. However, it will not be visible if the function returns false, and if you try to access the URL directly, Lift will call the isAdmin_? function, which will redirect the user to / if the function returns false.

We also used LocGroup to divide the SiteMap into three logical groups: content, footer, and admin. So, the SiteMap has three groups, and one of them is hidden and has a submenu that is only visible to users with the right credentials. We now need to understand how this structure is transformed into HTML by Lift.

Looking closely at the HTML snippet, you'll find invocations to the MenuBuilder snippet. But, we are not just invoking snippets here. We are invoking and passing parameters to them.

Lift uses these parameters as filters and will render only the items that have LocGroup specified by the parameter. When we say ?group=content, we are telling Lift to render only the items with LocGroup("content").

The final point to cover is the menu with LocGroup("admin") which we defined as hidden; a menu item defined as hidden is not rendered by Lift when the MenuBuilder snippet is invoked. If the menu item is not rendered, how will we access the items in the admin menu? As it turns out, the only item that is hidden is the one defined as hidden. Submenus are not affected. But we still want to let only users with the right credentials access the admin menu. To accomplish this, I created a function to tell Lift whether or not it should render the admin submenu items. Lift will only show it if we pass the admin parameter in the URL as true.

The isAdmin_? function is executed on every request and will be evaluated as true if you pass the admin parameter, and then Lift will render the menu. In this case, I used LocGroup("admin") to group all items together, so I can render them in a different area of the page.