How to export a DataTable to Xml with ALL columns as attributes?

Question

Question: I\'m exporting a System.Data.DataTable to XML. So far it works fine. But I want to have all the data in attributes, which works fine as well. But my problem now, i

Answer 1

I have been searching the whole world for a solution of writing null fields to XML using DataSet.WriteXML(). I found that following works in a performance optimized way. I have created a function for your convenience. Change your dataset tables one after the other by calling the following function and replacing the tables.

private DataTable GetNullFilledDataTableForXML(DataTable dtSource)
{
    // Create a target table with same structure as source and fields as strings
    // We can change the column datatype as long as there is no data loaded
    DataTable dtTarget = dtSource.Clone();
    foreach (DataColumn col in dtTarget.Columns)
        col.DataType = typeof(string);

    // Start importing the source into target by ItemArray copying which 
    // is found to be reasonably fast for null operations. VS 2015 is reporting
    // 500-525 milliseconds for loading 100,000 records x 10 columns 
    // after null conversion in every cell 
    // The speed may be usable in many circumstances.
    // Machine config: i5 2nd Gen, 8 GB RAM, Windows 7 64bit, VS 2015 Update 1
    int colCountInTarget = dtTarget.Columns.Count;
    foreach (DataRow sourceRow in dtSource.Rows)
    {
        // Get a new row loaded with data from source row
        DataRow targetRow = dtTarget.NewRow();
        targetRow.ItemArray = sourceRow.ItemArray;

        // Update DBNull.Values to empty string in the new (target) row
        // We can safely assign empty string since the target table columns
        // are all of string type
        for (int ctr = 0; ctr < colCountInTarget; ctr++)
            if (targetRow[ctr] == DBNull.Value)
                targetRow[ctr] = String.Empty;

        // Now add the null filled row to target datatable
        dtTarget.Rows.Add(targetRow);
    }

    // Return the target datatable
    return dtTarget;
}