Correct Methods to Retrieve Cell Values in GridView's RowDataBound Event

Problem Background and Common Pitfalls

In ASP.NET development, the GridView control is a common component for data display, and the RowDataBound event is used to execute custom logic when data is bound to each row. Many developers attempt to directly retrieve cell text via e.Row.Cells[index].Text, but in TemplateField scenarios, this approach often returns an empty string.

Data Binding Mechanism of TemplateField

When using a TemplateField with bound text, the ASP.NET runtime does not directly assign the text to the Cell's Text property. Instead, it dynamically creates controls (such as LiteralControl or DataBoundLiteralControl) to host the data. This is why direct access to the Text property fails—the text is actually stored within the properties of these child controls.

Optimal Solution: Using the FindControl Method

The recommended approach is to explicitly use server controls (e.g., Label or Literal) within the TemplateField and reference them by name via the FindControl method:

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        Label lblPercentage = (Label)e.Row.FindControl("lblPercentage");
        if (lblPercentage != null)
        {
            string percentage = lblPercentage.Text;
            // Execute subsequent logic
        }
    }
}

The corresponding TemplateField definition should be modified as:

<asp:TemplateField HeaderText="# Percentage click throughs">
    <ItemTemplate>
        <asp:Label ID="lblPercentage" runat="server" 
                   Text='<%# AddPercentClickThroughs((int)Eval("EmailSummary.pLinksClicked"), (int)Eval("NumberOfSends")) %>' />
    </ItemTemplate>
</asp:TemplateField>

Alternative Approach: Direct Access to DataItem

If there is no need for control-level interaction, values can be retrieved directly from the data source, avoiding dependency on the UI structure:

string percentage = DataBinder.Eval(e.Row.DataItem, "PercentageColumn").ToString();

This method is more efficient but requires the corresponding field to be present in the data source.

Practices to Avoid Hard-Coded Indices

Using numeric indices (e.g., Cells[7]) makes code fragile and prone to errors when column order changes. Named references (via FindControl) or column name access (e.g., DataBinder.Eval) significantly enhance code maintainability.

Conclusion

When retrieving cell values in the GridView's RowDataBound event, priority should be given to the FindControl method with named controls or direct access to the DataItem property. These methods not only resolve the empty text issue but also improve code robustness and readability.