UserControl inside DataList - asp.net

Question

I have a UserControl inside DataList, I fill the controls inside the usercontrol according to the PrimeryKey of the DataList's data. At first load program behaves as expected but when user changes page index all the MessageID's returns 0, most probably value coming with
<%# Eval("id").toString()%> is lost. I dont want to hard code the usercontrol because i used it in many place in the project, it makes the code maintainable. How can i correct this behaviour? Thanks in advance.
My code is below:
<asp:DataList ID="DataList1" runat="server" Width="658px">
<ItemTemplate>
<table style="width: 100%;">
<tr>
<td style="font-weight: 700; color: #FF0000; font-size: medium; font-size: 10pt; font-family: Tahoma">
<%# Eval("hadding") +" ["+Eval("startTime")+" - "+Eval("endTime")+"]"%>
</td>
</tr>
<tr>
<td style="font-weight: 700; font-size: 10pt; font-family: Tahoma">
<%# Eval("location") %>
</td>
</tr>
<tr>
<td>
<uc1:MyUserControl ID="MyUserControl1" runat="server" MessageID='<%# Eval("id").toString()%>' />
</td>
</tr>
</table>
</ItemTemplate>
</asp:DataList>
<table>
<tr>
<td>
<asp:Button ID="btnfirst" runat="server" Font-Bold="true" Text="<<" Height="31px"
Width="43px" OnClick="btnfirst_Click" /></td>
<td>
<asp:Button ID="btnprevious" runat="server" Font-Bold="true" Text="<" Height="31px"
Width="43px" OnClick="btnprevious_Click" /></td>
<td>
<asp:Button ID="btnnext" runat="server" Font-Bold="true" Text=">" Height="31px"
Width="43px" OnClick="btnnext_Click" /></td>
<td>
<asp:Button ID="btnlast" runat="server" Font-Bold="true" Text=">>" Height="31px"
Width="43px" OnClick="btnlast_Click" /></td>
</tr>
</table>
and my user control:
Partial Class MyUserControl
Inherits System.Web.UI.UserControl
Private _messageID As Integer
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If (_messageID > 0) Then
Fill(_messageID)
End If
End Sub
Public Property MessageID As Integer
Get
Return _messageID
End Get
Set(value As Integer)
_messageID = value
End Set
End Property
Protected Sub Fill(messageID As Integer)
'Some code
End Sub
End Class

Answer 1

Difficult to answer without looking at the whole page lifecycle, but you may try to store the MessageId in your control's ViewState, like this :
Public Property MessageID As Integer
Get
If (Me.ViewState("VSMessageID") IsNot Nothing) Then
return CType(Me.ViewState("VSMessageID "), Integer)
else
return 0 // arbitrary value
End Get
Set(value As Integer)
Me.ViewState.Add("VSMessageID", value)
End Set
End Property
Then :
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If (MessageID > 0) Then
Fill(MessageID )
End If
End Sub
See http://msdn.microsoft.com/en-us/library/ms227551%28v=vs.85%29.aspx?cs-save-lang=1&cs-lang=vb#code-snippet-1
Sorry if bad VB.Net syntax

Answer 2

I solved the problem by changing the usercontrol as such:
Partial Class MyUserControl
Inherits System.Web.UI.UserControl
Public Property MessageID As Integer
Get
Return 0
End Get
Set(value As Integer)
Fill(value)
End Set
End Property
Protected Sub Fill(messageID As Integer)
'Some code
End Sub
End Class
As jbl said, this is because of the page lifecycle. OnPageIndexChange event of an ASPxDataview or on your custom PageIndexChange event for asp.net DataList, code work as such:
DataList (or ASPxDataview ) Load
UserControl Property setting
UserControl Load
PageIndexChange event
UserControl Load
UserControl Property setting
That's why on UserControl.Load Property is not set.