Question

I have the following GridView, which has as DataSource a List<T>:

<asp:GridView ID="gvDownloads" UseAccessibleHeader="False"
              AutoGenerateColumns="False" runat="server" PageSize="10" AllowPaging="true" 
              CellPadding="4" CellSpacing="1" GridLines="None" DataKeyNames="productid">
             <EmptyDataTemplate>
                No licenses found 
             </EmptyDataTemplate>
             <Columns>
                <asp:TemplateField HeaderText="Id" >
                   <ItemTemplate>
                       <%# Eval("ProductId")%>
                   </ItemTemplate>
                </asp:TemplateField> 
                <asp:TemplateField HeaderText="Product Name">
                   <ItemTemplate>
                       <%# Eval("ProductName")%>
                   </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="Stock Code">
                   <ItemTemplate>
                       <%# Eval("StockCode")%>
                   </ItemTemplate>
                </asp:TemplateField>
            </Columns>
</asp:GridView>

Which renders correctly and with the proper values.

Now, I would like to modify on the fly the field StockCode and in order to do so I have in my code behind:

Sub gvDownloads_RowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs) Handles gvDownlads.RowDataBound

    If e.Row.RowType = DataControlRowType.DataRow Then

         e.Row.Cells(2).Text = StockCodeConverter.Convert(e.Row.Cells(2).Text)

    End If
End Sub

But the data cells corresponding to StockCode are empty. Now I tried to debug and for some reason the code finds just the value of the header row. The values of the other rows are string.Empty or &nsbp. Might it depend on the List as DataSource?

Answer 1

Use ASP.NET controls instead, for example Labels:

If e.Row.RowType = DataControlRowType.DataRow Then
     Dim lblStockCode = DirectCast(e.Row.FindControl("lblStockCode"), Label)
    lblStockCode.Text = StockCodeConverter.Convert(lblStockCode.Text)
End If

on aspx:

<asp:TemplateField HeaderText="Stock Code">
    <ItemTemplate>
        <asp:Label Id="LblStockCode" runat="server" Text='<%# Eval("StockCode") %>'></asp:label>
    </ItemTemplate>
</asp:TemplateField>

You can even omit the Eval on aspx and set the Text property completely in codebehind:

If e.Row.RowType = DataControlRowType.DataRow Then
     Dim row = DirectCast(e.Row.DataItem, DataRowView)
     Dim lblStockCode = DirectCast(e.Row.FindControl("lblStockCode"), Label)
    lblStockCode.Text = StockCodeConverter.Convert(row["StockCode"].ToString)
End If

Edit: If you want to stay with your text and also with the TemplateField you could cast the first control in the cell which is a autogenerated DataBoundLiteralControl when there’s only text and use it’s Text property.

Dim StockCode = DirectCast(e.Row.Cells(2).Controls(0), DataBoundLiteralControl).Text

But that makes your code less readable in my opinion.