How to create ASP.NET user/server control that uses a list of asp:ListItem as child controls?

Question

I am looking to create a user/server control that will be created with something like the following:

<my:MyListControl runat="server">
   <asp:ListItem Text="Test1" Value="Test1" />
   <asp:ListItem Text="Test2" Value="Test2" />
</my:MyListControl>

I am just looking for a start here: Articles or code samples.

What base class should I inherit from? What to override?

Possibly how to customize what sub items my control accepts (my:ListItem instead of asp:ListItem).

What I am looking to do is create a very simple bread crumb control for a small section of my site. I have it all working with stock ASP.NET controls, but the items are added in code, which means fixing a spelling mistake or formatting bug involves a recompile, which is not ideal.

EDIT:

Here's my code with the addition of Josh's suggestion below:

Namespace MySite.Controls Partial Class BreadCrumbs Inherits UserControl

    Private m_BreadCrumbs As New List(Of BreadCrumbItem)

    <PersistenceMode(PersistenceMode.InnerProperty)> _
    Public Property Items() As List(Of BreadCrumbItem)
        Get
            Return m_BreadCrumbs
        End Get
        Set(ByVal value As List(Of BreadCrumbItem))
            m_BreadCrumbs = value
        End Set
    End Property

    Private Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
        Bind()
    End Sub

    Private Sub Bind()
        lvCrumbs.DataSource = Items
        Me.DataBind()
    End Sub
End Class

Public Class BreadCrumbItem
    Private m_Text As String
    Public Property Text() As String
        Get
            Return m_Text
        End Get
        Set(ByVal value As String)
            m_Text = value
        End Set
    End Property

    Private m_Url As String
    Public Property Url() As String
        Get
            Return m_Url
        End Get
        Set(ByVal value As String)
            m_Url = value
        End Set
    End Property
End Class

End Namespace

Then my page code looks like this:

<%@ Page Language="VB" AutoEventWireup="false" Inherits="MySite.MyPage" Title="My Page" Codebehind="MyPage.aspx.vb" %>
<%@ Register TagPrefix="my" Namespace="MySite.Controls" Assembly="MySite" %>
<my:BreadCrumbs ID="breadcrumbs" runat="server">
    <Items>
        <my:BreadCrumbItem Text="Another page" Url="AnotherPage.aspx" />
    </Items>
</my:BreadCrumbs>

Ovovitellin

What's the eventual HTML markup goal? Something like: <ul> <li>Test1</li> <li>Test2</li> </ul> What's the need for using ListItem and not some other type? – Gouty

Yes, the HTML that I am spitting out is ul/li. There is no need for asp:ListItem, just didn't know what else to call it when I asked the question – Ovovitellin

Answer 1

You can add a property on a user control's code behind like:

[PersistenceMode(PersistenceMode.InnerProperty)]
public List<ListItem> Items
{
    get;
    set;
}

Your markup would then be:

<my:MyListControl runat="server">
  <Items>
    <asp:ListItem/>
  </Items>
</my:myListControl>

To make it so ListItem can be your own list item (Which I recommend doing as opposed to using asp.net.) You'll want to create your own class.

Here's an example of a Server Control I use (I removed a lot of the noise as such this is just a skeleton):

   [ToolboxData("<{0}:Menubar runat=server></{0}:Menubar>")]
    [System.ComponentModel.DesignTimeVisible(false)]
    public class Menubar : WebControl, IPostBackEventHandler
    {

        private List<MenuItem> _menuItems = new List<MenuItem>();
        [PersistenceMode(PersistenceMode.InnerProperty)]
        public List<MenuItem> MenuItems
        {
            get
            {
                return _menuItems;
            }
        }

    }
    [ToolboxItem(false)]
    [ParseChildren(true, "MenuItems")]
    public class MenuItem
    {
        private string _clientClick;
        private List<MenuItem> _menuItems = new List<MenuItem>();

        [Localizable(true)]
        public string Title { get; set; }
        public string Href { get; set; }
        public string Id { get; set; }
        [PersistenceMode(PersistenceMode.InnerDefaultProperty)]
        public List<MenuItem> MenuItems
        {
            get { return _menuItems; }
            set { _menuItems = value; }
        }
    }

Now I can use this like:

<my:Menubar runat="server" ID="menuBar">
    <MenuItems>
        <my:MenuItem Title="Save" Href="javascript:saveItem(this);"  />
        <my:MenuItem Title="Print" Href="javascript:void(0);">
            <MenuItems>
                <my:MenuItem Title="Preview" Href=""/>
                <my:MenuItem Title="To Pdf" Href="javascript:"/>
            </MenuItems>
        </my:MenuItem>
    </MenuItems>
</my:Menubar>

Golfer

This appears to be what I need. My only hang up now is why my @Register TagPrefix="my" Namespace="MySite.Controls" doesn't work to get the custom list item class? Any ideas? It gets the parent control (Menubar in your example) but I cannot do my:MyListItem inside the Items tag. – Ovovitellin

Never mind. Needed to add the Assembly param to the @Register directive. Now it works. Thanks Josh – Ovovitellin

Answer 2

Use an asp:Repeater then bind it to a List of the objects you want in your breadcrumb. You can use the template to customize the items themselves and the separators.

Jacey

I wanted something a little more defined than the repeater control – Ovovitellin