Hi,

You can create a custom data exporter like this:

[ServiceConfiguration(ServiceType = typeof(DataExporterBase))]
public class CustomCsvDataExporter : CSVDataExporter
{
    public override string Export(DataTable dataTable)
    {        
        // modify data
        return base.Export(dataTable);
    }
}

For excel you need to inherit from XLSXDataExporter and override other methods.

Hope this helps!

Here's an updated version

[ServiceConfiguration(ServiceType = typeof(DataExporterBase))]
public class CustomExcelDataExporter : XLSXDataExporter
{
    private readonly IContentRepository _contentRepository = ServiceLocator.Current.GetInstance<IContentRepository>();

    protected override void EncodeXmlStringsFromDataTable(DataTable dataTable)
    {
        foreach (DataRow row in dataTable.Rows)
        {
            string language = row["SYSTEMCOLUMN_Language"].ToString();
            int pageId = int.Parse(row["Submitted_from"].ToString());

            if (_contentRepository.TryGet(
                new ContentReference(pageId), 
                new CultureInfo(language),
                out PageData page))
            {
                row["Submitted_from"] = page.Name;
            }
        }

        base.EncodeXmlStringsFromDataTable(dataTable);
    }
}

Thanks Dejan, this is just what I was looking for

I tested your code and it works perfectly when the UI language is English, but when I change it the name of the "Submitted_from" column is also changed.

Any idea how I can get the localized column name? 

I also considered doing something like ColumnCount-5 as the index but this is obviously prone to break if a new standard field is added to form submissions.

Try this:

[ServiceConfiguration(ServiceType = typeof(DataExporterBase))]
public class CustomExcelDataExporter : XLSXDataExporter
{
    private readonly IContentRepository _contentRepository = ServiceLocator.Current.GetInstance<IContentRepository>();

    protected override void EncodeXmlStringsFromDataTable(DataTable dataTable)
    {
        string columnName = LocalizationService.Current
            .GetString("/episerver/forms/formdataview/hostedpage")
            .Replace(" ", "_");

        foreach (DataRow row in dataTable.Rows)
        {
            string language = row["SYSTEMCOLUMN_Language"].ToString();
            int pageId = int.Parse(row[columnName].ToString());

            if (_contentRepository.TryGet(
                new ContentReference(pageId),
                new CultureInfo(language),
                out PageData page))
            {
                row[columnName] = page.Name;
            }
        }

        base.EncodeXmlStringsFromDataTable(dataTable);
    }
}

Hope this helps :)