Question

I am creating a User Control where I have a property called Items. Items is of type LibraryPanelBarItemCollection (custom class) which contains a collection of LibraryPanelBarItem objects. I would like to be able to add these at design time by using the Collection editor that VS uses for adding things such as treenodes/listviewitems. Ideally I would also be able to declaratively add them to the html syntax. I can get the Items property to show up but I get no intellisense to add the items between the opening and closing tags.

In my user control I have the following property declared with the attributes

 <ParseChildren(True, "Items")> _
 Public Class LibraryPanelBar
Inherits System.Web.UI.UserControl

<PersistenceMode(PersistenceMode.InnerDefaultProperty)> _
<Browsable(True)> _
<DesignerSerializationVisibility(DesignerSerializationVisibility.Content)> _
Public Property Items As LibraryPanelBarItemCollection

...Do Some Stuff...

End Class

Here are my custom classes for the LibraryPanelBarItem and LibraryPanelBarItemCollection

Public Class LibraryPanelBarItem
<BindableAttribute(True)> _
Public Property ImageUrl As String

<BindableAttribute(True)> _
Public Property NavigateUrl As String
Public Property Text As String
Public Property Disabled As Boolean
Public Property ID As String
<PersistenceMode(PersistenceMode.InnerDefaultProperty)> _
Public Property Items As LibraryPanelBarItemCollection
Public ReadOnly Property HasChildren() As Boolean
    Get
        If Items.Count > 0 Then
            Return True
        Else
            Return False
        End If
    End Get
End Property


Public Sub New()
    Items = New LibraryPanelBarItemCollection
End Sub
End Class

Public Class LibraryPanelBarItemCollection
Inherits CollectionBase

Default Public ReadOnly Property Item(Index As Integer) As LibraryPanelBarItem
    Get
        Return DirectCast(List(Index), LibraryPanelBarItem)
    End Get
End Property

Public Function Contains(itemType As LibraryPanelBarItem) As Boolean
    Return List.Contains(itemType)
End Function

Public Function Add(itemType As LibraryPanelBarItem) As Integer
    Return List.Add(itemType)
End Function

Public Sub Remove(itemType As LibraryPanelBarItem)
    List.Remove(itemType)
End Sub

Public Sub Insert(index As Integer, itemType As LibraryPanelBarItem)
    List.Insert(index, itemType)
End Sub

Public Function IndexOf(itemType As LibraryPanelBarItem) As Integer
    Return List.IndexOf(itemType)
End Function

Public Sub New()

End Sub
End Class

Here is my current declaration in the aspx file:

 <uc1:LibraryPanelBar ID="LibraryPanelBar2" runat="server">
     <Items>
     </Items>
 </uc1:LibraryPanelBar>

Answer 1

The following should point you in the right direction. Feel free to comment if you need any further detail.

<ToolboxData("<{0}:LibraryPanelBar runat=""server""> </{0}:LibraryPanelBar>")>
Public Class LibraryPanelBar
    Inherits HierarchicalDataBoundControl

    Private _Items As New LibraryPanelBarItemCollection()

    <PersistenceMode(PersistenceMode.InnerProperty)> _
    <MergableProperty(False)> _
    <Editor("WebApplicationVB1.TreeNodeCollectionEditor,WebApplicationVB1", GetType(UITypeEditor))> _
    Public ReadOnly Property Items As LibraryPanelBarItemCollection
        Get
            Return _Items
        End Get
    End Property

    Protected Overrides Sub PerformSelect()

    End Sub

    Protected Overrides Sub ValidateDataSource(dataSource As Object)

    End Sub

    Protected Overrides Sub RenderContents(writer As System.Web.UI.HtmlTextWriter)
        writer.RenderBeginTag(HtmlTextWriterTag.Ul)
        For Each item As LibraryPanelBarItem In Items
            writer.RenderBeginTag(HtmlTextWriterTag.Li)
            RenderContentsRecursive(writer, item)
            writer.RenderEndTag() ' Li
        Next
        writer.RenderEndTag() ' Ul
    End Sub
    Private Sub RenderContentsRecursive(writer As System.Web.UI.HtmlTextWriter, item As LibraryPanelBarItem)
        writer.Write(item.Text)
        writer.WriteBreak()
        writer.RenderBeginTag(HtmlTextWriterTag.Ul)
        For Each subItem As LibraryPanelBarItem In item.Items
            writer.RenderBeginTag(HtmlTextWriterTag.Li)
            RenderContentsRecursive(writer, subItem)
            writer.RenderEndTag() ' Li
        Next
        writer.RenderEndTag() ' Ul
    End Sub
End Class

<ParseChildren(True, "Items")> _
Public Class LibraryPanelBarItem
    Implements IStateManager, ICloneable

    Private _Items As New LibraryPanelBarItemCollection()

    <BindableAttribute(True)> _
    Public Property ImageUrl As String

    <BindableAttribute(True)> _
    Public Property NavigateUrl As String
    Public Property Text As String
    Public Property Disabled As Boolean
    <Browsable(False)> _
<PersistenceMode(PersistenceMode.InnerDefaultProperty)> _
    Public ReadOnly Property Items As LibraryPanelBarItemCollection
        Get
            Return _Items
        End Get
    End Property
    Public ReadOnly Property HasChildren() As Boolean
        Get
            If Items.Count > 0 Then
                Return True
            Else
                Return False
            End If
        End Get
    End Property

    Public ReadOnly Property IsTrackingViewState As Boolean Implements System.Web.UI.IStateManager.IsTrackingViewState
        Get
            Throw New NotImplementedException()
        End Get
    End Property

    Public Sub LoadViewState(state As Object) Implements System.Web.UI.IStateManager.LoadViewState
        Throw New NotImplementedException()
    End Sub

    Public Function SaveViewState() As Object Implements System.Web.UI.IStateManager.SaveViewState
        Throw New NotImplementedException()
    End Function

    Public Sub TrackViewState() Implements System.Web.UI.IStateManager.TrackViewState
        Throw New NotImplementedException()
    End Sub

    Public Function Clone() As Object Implements System.ICloneable.Clone
        Throw New NotImplementedException()
    End Function
End Class

Public Class LibraryPanelBarItemCollection
    Inherits CollectionBase
    Implements IStateManager

    Default Public ReadOnly Property Item(Index As Integer) As LibraryPanelBarItem
        Get
            Return DirectCast(List(Index), LibraryPanelBarItem)
        End Get
    End Property

    Public Function Contains(itemType As LibraryPanelBarItem) As Boolean
        Return List.Contains(itemType)
    End Function

    Public Function Add(itemType As LibraryPanelBarItem) As Integer
        Return List.Add(itemType)
    End Function

    Public Sub Remove(itemType As LibraryPanelBarItem)
        List.Remove(itemType)
    End Sub

    Public Sub Insert(index As Integer, itemType As LibraryPanelBarItem)
        List.Insert(index, itemType)
    End Sub

    Public Function IndexOf(itemType As LibraryPanelBarItem) As Integer
        Return List.IndexOf(itemType)
    End Function

    Public ReadOnly Property IsTrackingViewState As Boolean Implements System.Web.UI.IStateManager.IsTrackingViewState
        Get
            Throw New NotImplementedException()
        End Get
    End Property

    Public Sub LoadViewState(state As Object) Implements System.Web.UI.IStateManager.LoadViewState
        Throw New NotImplementedException()
    End Sub

    Public Function SaveViewState() As Object Implements System.Web.UI.IStateManager.SaveViewState
        Throw New NotImplementedException()
    End Function

    Public Sub TrackViewState() Implements System.Web.UI.IStateManager.TrackViewState
        Throw New NotImplementedException()
    End Sub
End Class

Public Class LibraryPanelBarItemCollectionEditor
    Inherits System.Drawing.Design.UITypeEditor

    Public Overrides Function EditValue(context As System.ComponentModel.ITypeDescriptorContext, provider As System.IServiceProvider, value As Object) As Object
        Return MyBase.EditValue(context, provider, value)
    End Function

    Public Overrides Function GetEditStyle(context As System.ComponentModel.ITypeDescriptorContext) As System.Drawing.Design.UITypeEditorEditStyle
        Return MyBase.GetEditStyle(context)
    End Function

End Class

EDIT: Added UI collection editor example.