Question

Update

In editing the question I have spotted my own mistake (invalid cast to a string.)

Many thanks to all, all suggestions most helpful.

Original Question

I have an .aspx page with a GridView, databound to an ObjectDataSource which is filled with a DataSet containing a DataTable.

When handling the RowDataBound callback on the GridView however, I am unable to reference columns in the underlying dataset by column name, they just return an object of type DBNull. So:

    protected void accountsGV_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            // One way:
            // This works, but uses a hard coded column index which
            // I want to replace.
            if (e.Row.Cells[11].Text != " ")
            {
                // Apply certain styles to the row depending on
                // the contents of the cell.
            }


            // Another way. This doesn't work - "date" is always DBNull.
            DataRow row = (e.Row.DataItem as DataRowView).Row;
            DateTime date;

            if(!Convert.IsDBNull(row["date"]))
            {
                date = (DateTime)row["date"]);

                if (date < SomeConstantDate)
                {
                    // Apply certain styles to the row depending on
                    // the contents of the cell.
                }
            }
        }
    }

So specifically:

• row["date"] returns an object of type DBNull.
• row[11] returns a DateTime.
• row.Table.Columns["date"] returns a valid DataColumn
• row[row.Table.Columns["date"]] returns an object of type DBNull.

Can anyone suggest why this might be happening?

Setup

<asp:GridView ID="GV" runat="server" DataSourceID="ODS"
    AutoGenerateColumns="false"
    ... snip ...
    onrowdatabound="GV_RowDataBound" >
    <Columns> ... </Columns>
 </asp:GridView>


 <asp:ObjectDataSource ID="ODS" runat="server" 
    SelectMethod="getData"
    ... snip ...
</asp:ObjectDataSource>

Answer 1

there are a few things to consider.

1. e.Row.Cells is referring to the formatted output, not the object itself.
2. null values are rendered as non-blanking white space hence  
3. column names are case sensative. “Date” != “date”
4. the column name implies the type of the value is a DateTime object, not a string, so softly casting from a DateTime to string will return null, not the string value of the DateTime object.

instead try this

var data = (DataRowView)e.Row.DataItem;
var date = data["Date"];
if(date != null and date.ToString() == "...")
{
   do something based on the value of date.
}