Set the Value Property of the ListItem to the ID.

Set the Text Property of the ListItem to the "Description" (Or whatever you want to display in the DropDownList).

When the SelectedIndexChanged event occurs, retrieve the SelectedValue to get the ID.

-Frinny

Did you try the CType methods?

The thing is that you can't store the whole object in the ListItem...
You're going to have to store something that identifies the object (in the value) so that you can retrieve it again.

-Frinny

Normally I don't spell out what I was hinting at but today I'm in a strange mood.

So, what I recommended before was to add code that will handle casting the ValuePair type into a ListItem type. To do this you have to implement some code for the CType operator.


This is what your code would look like for the ValuePair class:

Public Class ValuePair

    Public Value As Object
    Public Description As String
    Public Reference As String

 
    Public Sub New(ByVal NewValue As Object, ByVal NewDescription As String, Optional ByVal NewRef As String = "")
        Value = NewValue
        Description = NewDescription
        Reference = NewRef
    End Sub

    Public Property UnderlyingValue() As String
        Get
            Return Value
        End Get
        Set(ByVal Thisvalue As String)
            Value = Thisvalue
        End Set
    End Property

    Public Overrides Function ToString() As String
        Return Description
    End Function
    Public Shared Narrowing Operator CType(ByVal initialData As ListItem) As ValuePair
        Return New ValuePair(initialData.Value, initialData.Text)
    End Operator

    Public Shared Widening Operator CType(ByVal initialData As ValuePair) As ListItem
        Return New ListItem(initialData.Description, initialData.Value)
    End Operator

End Class

I modified your PopulateCombo method to test this out and it works fine:

    Public Sub PopulateCombo()
        cboClientID.Items.Clear()

        'Dim cmdDevices As SqlCommand = New SqlCommand("GetDevices", DBConnection.MyConnObj)'
        'cmdDevices.CommandType = CommandType.StoredProcedure'

        'With cmdDevices'
        '    .Parameters.Add("@ProductID", SqlDbType.VarChar).Value = ""'
        '    .Parameters.Add("@ClientID", SqlDbType.VarChar).Value = "sa"'
        '    .Parameters.Add("@RecordDeleted", SqlDbType.Bit).Value = 0'
        'End With'
        'dtClients.Load(cmdDevices.ExecuteReader())'

        'For Each dr As DataRow In dtClients.Rows'
        '    cboClientID.Items.Add(New ValuePair(dr.Item("Client_ID"), dr.Item("Client_Name")).ToString)'
        'Next'


        For i As Integer = 1 To 10
            cboClientID.Items.Add(New ValuePair(i, String.Format("{0} {1}", "Description for Item", i.ToString)))
        Next
    End Sub

There's another approach that you can take though.
You could convert your Public members into Properties to allow ASP.Net to bind the DropDownList to them. (In my opinion using using Properties is just better programming practice anyways).

Using this approach you would convert the Public members in your ValuePair class into properties like this:

Public Class ValuePair

    'Public Value As Object'
    'Public Description As String'
    'Public Reference As String'

    Private _value As Object
    Private _description As String
    Private _reference As String
    Public Property Value() As Object
        Get
            Return _value
        End Get
        Set(ByVal value As Object)
            _value = value
        End Set
    End Property
    Public Property Description() As String
        Get
            Return _description
        End Get
        Set(ByVal value As String)
            _description = value
        End Set
    End Property
    Public Property Reference() As String
        Get
            Return _reference
        End Get
        Set(ByVal value As String)
            _reference = value
        End Set
    End Property

    Public Sub New(ByVal NewValue As Object, ByVal NewDescription As String, Optional ByVal NewRef As String = "")
        Value = NewValue
        Description = NewDescription
        Reference = NewRef
    End Sub

    Public Property UnderlyingValue() As String
        Get
            Return Value
        End Get
        Set(ByVal Thisvalue As String)
            Value = Thisvalue
        End Set
    End Property

    Public Overrides Function ToString() As String
        Return Description
    End Function
End Class

Then in your PopulateCombo method you would:

• Create a list of ValuePair objects based on the information retrieved from the database
  
• Set the comboClientID.DataSource to this list
  
• Set the comboClientID.DataTextField to the property that you want displayed as text (probably the "Description" property)
  
• Set the comboClientID.DataValueField to the property that you want to use as the value for the item (probably the reference....)
  
• Call the comboClientID.DataBind method to bind the data to the DropDownList

Like this:

Partial Public Class _Default
    Inherits System.Web.UI.Page

    Private _vpItems As List(Of ValuePair)

    Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If IsPostBack = False Then
            PopulateCombo()
        Else
            _vpItems = TryCast(Session("_vpItems"), List(Of ValuePair))
        End If
    End Sub
    Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
        cboClientID.DataSource = _vpItems
        cboClientID.DataTextField = "Description"
        cboClientID.DataValueField = "Value"
        cboClientID.DataBind()
    End Sub
    Public Sub PopulateCombo()
        cboClientID.Items.Clear()

        'Dim cmdDevices As SqlCommand = New SqlCommand("GetDevices", DBConnection.MyConnObj)'
        'cmdDevices.CommandType = CommandType.StoredProcedure;'

        'With cmdDevices'
        '    .Parameters.Add("@ProductID", SqlDbType.VarChar).Value = ""'
        '    .Parameters.Add("@ClientID", SqlDbType.VarChar).Value = "sa"'
        '    .Parameters.Add("@RecordDeleted", SqlDbType.Bit).Value = 0'
        'End With'
        'dtClients.Load(cmdDevices.ExecuteReader())'

        'For Each dr As DataRow In dtClients.Rows'
        '    cboClientID.Items.Add(New ValuePair(dr.Item("Client_ID"), dr.Item("Client_Name")).ToString)'
        'Next'


        _vpItems = New List(Of ValuePair)
        For i As Integer = 1 To 10
            _vpItems.Add(New ValuePair(i, String.Format("{0} {1}", "Description for Item", i.ToString)))
        Next
        Session("_vpItems") = _vpItems
       
    End Sub
End Class

-Frinny

Oh yeah, I wanted to tell you that you should be referring to the MSDN Library for documentation on .NET controls and other programming concepts. It has all the documentation you need to figure out how to use the ASP.NET DropDownList.