User Control in GridView - asp.net

Question

I'm trying to revisit this as I can't seem to find an answer. I have created a User Control which works awfully well when I hard code in the Parent_ID. However, I'd like to have the Parent_ID assigned dynamically according to a value from a GridView's row.
Here is the User Control's CodeBehind:
Public Class Comments
Inherits System.Web.UI.UserControl
Public _name As String
<System.ComponentModel.Bindable(True), System.ComponentModel.Browsable(True)> _
Public Property Parent_ID() As String
Get
Return _name
End Get
Set(value As String)
_name = value
End Set
End Property
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
If Parent_ID Is Nothing Then Parent_ID = "-1"
DataSource_Comments.FilterParameters(0).DefaultValue = Parent_ID
'lbl_Parent_Alert.Text = "Parent_ID: " & Parent_ID
End If
End Sub
End Class
ASP.net aspx page:
<%# Page Title="About Us" Language="vb" MasterPageFile="~/Site.Master" AutoEventWireup="false"
CodeBehind="About.aspx.vb" Inherits="MOO.About" %>
<%# Register TagPrefix="uc" TagName="Comments_Control" Src="~/Comments.ascx" %>
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<asp:SqlDataSource ID="DataSource_Missed_Yesterday" runat="server"
ConnectionString="<%$ ConnectionStrings:MainMOOConnectionString %>"
SelectCommand="SELECT * FROM func_Missed_Yesterday() Order By Total_Price DESC"
>
</asp:SqlDataSource>
<asp:GridView ID="GV_Missed_Yesterday" runat="server" DataSourceID="DataSource_Missed_Yesterday"
AutoGenerateColumns="false" CssClass="Grid_View">
<Columns>
<asp:BoundField DataField="num_Order_Num" HeaderText="Order Number"/>
<asp:BoundField DataField="mem_Order_Notes" HeaderText="Order Notes"/>
<asp:TemplateField HeaderText="Order Notes">
<ItemTemplate>
<asp:Label ID ='lbl' runat="server" text='<%#Eval("num_Order_Num") %>'/>
<uc:Comments_Control id="Comments_Control_ID" runat="server" Parent_ID='<%#Eval("num_Order_Num") %>' />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
</asp:Content>
Aspx.vb page:
Imports System.Data
Public Class About
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
End Sub
Sub GV_Missed_Yesterday_DataBound(sender As Object, e As GridViewRowEventArgs) Handles GV_Missed_Yesterday.RowDataBound
If e.Row.RowType = DataControlRowType.DataRow Then
End If
End Sub
End Class
Again, if I hard code this line:
<uc:Comments_Control id="Comments_Control_ID" runat="server" Parent_ID='<%#Eval("num_Order_Num") %>' />
As:
<uc:Comments_Control id="Comments_Control_ID" runat="server" Parent_ID='1162519' />
I see the appropriate comments for Order 1162519. When I leave it as Eval("num_Order_Num"), I get nothing.
I thank you in advance for pointing me in the right direction.
Thanks,
Rob

Answer 1

I could be wrong, but I believe that the controls in a template are first created (at which time your Page_Load event handler would run in the user control) and then any binding language expressions are evaluated. So by testing the value of Parent_ID in the user control's Page_Load routine, you're catching it too early.
Try using the PreRender event instead of the Load event to test Parent_ID for a value. That will execute right before rendering, well after any binding expressions have been evaluated.

Answer 2

Yeap... Ann L. was correct. The controls in a template are created first than the binding event.
You could also use the GV_Missed_Yesterday_DataBound method, if you couldn't use the PreRender. Some cases, you must do the operations before the prerender.
So you could set the Parent_ID for the control at the DataBound method and also create a method in the Comments_Control that executes the code :
DataSource_Comments.FilterParameters(0).DefaultValue = Parent_ID
For the same problems most of times there is a lot of possible solutions.
I've written this new solution in order to satisfy anyone who face the same problem but can't use the PreRender event.

Answer 3

You need to do a Page.DataBind() on the page load of your User Control.