How to find a control inside a TemplateField in Gridview

I have a gridView with a textBox inside a templateField. I wan to extract the text of the textBox if a checkbox is marked in the row.

I have the gridView defined as follows

    <asp:GridView ID="GV_Comments" runat="server" AutoGenerateColumns="False" DataKeyNames="id"
        DataSourceID="SQL_Comments">
        <Columns>
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:CheckBox runat="server" ID="Comment_Select" />
                </ItemTemplate>
            </asp:TemplateField>
            <asp:BoundField DataField="ID" HeaderText="ID" ReadOnly="True" SortExpression="ID" />
            <asp:TemplateField HeaderText="comment" SortExpression="comment">
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%# Bind("comment") %>'></asp:Label>
                </ItemTemplate>
                <EditItemTemplate>
                    <asp:TextBox ID="CommentForPeriod" runat="server" Text='<%# Bind("comment") %>'></asp:TextBox>
                </EditItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView> 
    <asp:Button ID="B_Load" runat="server" Text="Transfer Selection" onclick="B_Load_Click" />
    <br />
    <asp:TextBox ID="CompiledText" runat="server" Width="662px" Rows="10" 
        TextMode="MultiLine"></asp:TextBox>

And the code as follows

Protected Sub B_Load_Click(ByVal sender As Object, ByVal e As EventArgs) '(sender As Object, e As System.EventArgs) Handles B_Load.Click
    Dim FullText As String = ""
    For Each row As GridViewRow In GV_Comments.Rows
        Dim CB_Control As CheckBox = CType(row.FindControl("Comment_Select"), CheckBox)
        Dim Txt_Control As TextBox = CType(row.FindControl("CommentForPeriod"), TextBox)
        If CB_Control IsNot Nothing AndAlso CB_Control.Checked AndAlso Txt_Control IsNot Nothing Then
            FullText = FullText & Txt_Control.Text & "<br/>"
        End If
    Next row
    CompiledText.Text = FullText.ToString
End Sub

When I debug the code I can see that the Checkbox control is found but not the TextBox control. Would anyone see why?

Solution

You can't do like this. When you click the button: B_Load, then GridView is NOT in Edit mode. And this is why you can't get the TextBox, which is in EditItemTemplate.

You can only get the controls inside <ItemTemplate> in your button click as gridview is in Normal display Mode. <EditItemTemplate> controls are rendered only when GridView enters Edit mode.

So, you need to get the value of the Label: Label1 here actually, which has the same value and is inside <ItemTemplate> .

 Dim Lbl_Control As Label= CType(row.FindControl("Label1"), Label)

// button click as usual, just get and check the value of Label control, rather than TextBox control.

Protected Sub B_Load_Click(ByVal sender As Object, ByVal e As EventArgs) '(sender As
                           Object, e As System.EventArgs) Handles B_Load.Click
    Dim FullText As String = ""
    For Each row As GridViewRow In GV_Comments.Rows
        Dim CB_Control As CheckBox = CType(row.FindControl("Comment_Select"), 
                                           CheckBox)
        Dim Lbl_Control As Label= CType(row.FindControl("Label1"), Label)
        If CB_Control IsNot Nothing AndAlso CB_Control.Checked AndAlso Lbl_Control
           IsNot Nothing Then
            FullText = FullText &  Lbl_Control.Text & "<br/>"
        End If
    Next row
    CompiledText.Text = FullText.ToString
End Sub