Question

I have a ViewModel:

public class Page
{
    public int Id { get; set; }
    public Page Parent { get; set; }
    public string Name { get; set; }
    public string Title { get; set; }
}

I am passing that model to a view, and i need to create a hierarchical menu based on the model:

<ul>
    <li>Page
        <ul>
            <li>Sub Page</li>
        </ul>
    </li>

Through no lack of effort at all i am unable to figure out how i will be doing this recursive loop in the view.

I can create the markup in my controller, but that’s not test friendly.

Any Ideas?

Answer 1

there are many ways to display dynamicly generated menus and i will post my way of doing it, I have two classes Menu & MenuItem (a Menu is just a wrapper for a list of MenuItems which are the actual >”real” links) and then i have a NavigationViewModel to wrap everything.

public class MenuItem
{
    public int MenuID { get; set; }
    public int ID { get; set; }
    public String Label { get; set; }
    public String Link { get; set; }
    public Boolean Show { get; set; }

    public MenuItem(int menuId, int id, string label, string link, Boolean show)
    {
        this.MenuID = menuId;
        this.ID = id;
        this.Label = label;
        this.Link = link;
        this.Show = show;
    }
}

//

public class Menu
{
    public int ID { get; set; }
    public string Name { get; set; }
    public List<MenuItem> MenuItems { get; set; }

    public Menu(int id, string name)
    {
        this.ID = id;
        this.Name = name;
        this.MenuItems = new List<MenuItem>();
    }

}

// this is NavigationModel that wrap everything.

public class NavigationModel
{
    public int currentMenuID { get; set; }   
    // used to determine the current displayed Menu to add
    // the "current" class to it. (to be set in the controller)

    public int currentMenuItemID { get; set; } 
    // used to determine the current displayed MenuItem to add
    // the "current" class to it. (to be set in the controller)

    public List<Menu> Menus { get; set; }


    public NavigationModel()
    {
        this.Menus = new List<Menu>();
        // Set Default Menu ( Menu 1 )
        this.currentMenuID = 1;
        // Set Default Menau Item ( None )
        this.currentMenuItemID = 0;
    }
}

// This is an example of a method that builds a NavigationModel.

private static NavigationModel BuildNavigationMenu(User currentUser, string rootURL)
    {
        string loginURL = rootURL + "Account/LogOn";

        // Main Menu
        Menu MainMenu = new Menu(1, "Home");
        MainMenu.MenuItems.Add(new MenuItem(1, 1, "Welcome", rootURL, true));
        MainMenu.MenuItems.Add(new MenuItem(1, 2, "How It Works", rootURL + "Home/HowDoesItWork", true));

        // Work Menu
        Menu WorkMenu = new Menu(2, "Work");
        WorkMenu.MenuItems.Add(new MenuItem(2, 1, "Profile", rootURL + "User/Profile/" + currentUser.ID , true));
        WorkMenu.MenuItems.Add(new MenuItem(2, 2, "Customers", "#", true));

        // Add Menus To Navigation Model
        NavigationModel navigationMenu = new NavigationModel();
        navigationMenu.Menus.Add(MainMenu);
        navigationMenu.Menus.Add(HireMenu);

        return navigationMenu;
}

// I have a NavigationHelper that takes care of outputting the HTML with the following two methods.

Note: (this is a simplified version as in my implementation i use the id of the Menu & the MenuItem to locate the current menu that is being displayed and add the “current” CSS class to it”

public static string DisplayMenu(this HtmlHelper helper, NavigationModel navigationMenu)
{ 
    public static string DisplayMenu(this HtmlHelper helper, NavigationModel navigationMenu)
    {            
        String result = "<ul id='main-nav'>\n";
        foreach(Menu menu in navigationMenu.Menus)
        {
            result +=     "<li>\n";
            result +=         string.Format("<a href='#'> {0} </a>\n",helper.AttributeEncode(menu.Name));
            result +=         "<ul>\n";
            foreach(MenuItem item in menu.MenuItems)
            {
                result += NavigationHelper.ConvertToItem(helper, item);
            }
            result +=         "</ul>\n";
            result +=     "</li>\n";
        }
        result +=     "</ul>\n";

        return result;
    }

    private static string ConvertToItem(this HtmlHelper helper,MenuItem item)
    {
        if (item.Show)
        {
            return string.Format("<li><a href='{0}'>{1}</a></li>\n", helper.AttributeEncode(item.Link), helper.AttributeEncode(item.Label));
        }
        else { return ""; }   
    }
}

finally i have a following call in my Master to display the menu.

<!-- Navigation -->
<%= Html.DisplayMenu(Model.NavigationMenu) %>

Note: I have a strongly typed MasterPage with the type (BaseViewModel) that contains the property NavigationMenu of type NavigationModel

Connecting everything together.

In my example i have to supply my Views with a ViewModel (that inherits my BaseViewModel) at each action method to and then build the Menu (using a Builder Method that does most of the work so i don’t have to re type it in every action method). If you don’t use a BaseViewModel then you will need to find another way to build the Navigation Model and then pass the Navigation Model to your MasterPage.

For me i find having a strongly typed MasterPage to make things easier and cleaner. King wilder have a nice way of implementing them in his GolfTracker Series.