Question

I am reading in an XML file into a Dataset, then adding a new column, then assigning a value to each row in that column.

My program creates the new column and I can see that it has the BitmapImage datatype by looking at it in the debug screen while its running and using a messagebox to toString its datatype.

But when i try to assign something to that row’s column, it remains as ‘{}’ and when I attempt to use it it gives the the error ‘Unable to cast type DBNull to BitmapImage’;

ItemDS = new DataSet();
ItemDS.ReadXml(homeFolder + @"Items.xml", XmlReadMode.InferSchema);
ItemDS.Tables[0].Columns.Add("pic", typeof(BitmapImage));
MessageBox.Show(ItemDS.Tables[0].Columns[5].DataType.ToString());
foreach (DataRow theRow in ItemDS.Tables[0].Rows)
{
    try
    {
        theRow.ItemArray[5] = (SquareImageFromFile(NewDeployFolder + @"assets\images\items\" + theRow.ItemArray[3].ToString(), 120));
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.ToString());
    }
    combItem.Items.Add(theRow.ItemArray[0]);
}

When I run the assignment row, no error comes up, but nothing happens to the item array after the line is run.

Answer 1

I haven’t used DataTable much, but I’d expect ItemArray to make a copy of the data, rather than returning a “live” array which the DataRow tracks. I wouldn’t really have expected that to work. Try just setting the value via the indexer:

theRow[5] = (SquareImageFromFile(NewDeployFolder + @"assets\images\items\" + 
                                 theRow[3].ToString(), 120));

ItemArray is really meant to get or set values in bulk, rather than for a single value.