How can I change the format of the ColumnField column headings in EPPlus?

Question

I create a column field in EPPlus like so:

// Column field[s]
var monthYrColField = pivotTable.Fields["MonthYr"];
pivotTable.ColumnFields.Add(monthYrColField);

...that displays like so (the "201509" and "201510" columns):

I want those values to display instead as "Sep 15" and "Oct 15"

In Excel Interop it's done like this:

var monthField = pvt.PivotFields("MonthYr");
monthField.Orientation = XlPivotFieldOrientation.xlColumnField;
monthField.NumberFormat = "MMM yy";

...but in EPPlus the corresponding variable (monthYrColField) has no "NumberFormat" (or "Style") member.

I tried this:

pivotTableWorksheet.Column(2).Style.Numberformat.Format = "MMM yy";

...but, while it didn't complain or wreak havoc, also did not change the vals from "201509" and "201510"

How can I change the format of my ColumnField column headings in EPPlus from "untransformed" to "MMM yy" format?

UPDATE

For VDWWD:

As you can see by the comments, there are many things related to PivotTables which don't work or are hard to get to work in EPPlus; Excel Interop is a bear (and not a teddy or a Koala, but more like a grizzly) compared to EPPlus, but as to PivotTables, it seems that EPPlus is kind of half-baked to compared to Exterop's fried-to-a-crispness.

private void PopulatePivotTableSheet()
{
    string NORTHWEST_CORNER_OF_PIVOT_TABLE = "A6";
    AddPrePivotTableDataToPivotTableSheet();
    var dataRange = pivotDataWorksheet.Cells[pivotDataWorksheet.Dimension.Address];
    dataRange.AutoFitColumns();
    var pivotTable = pivotTableWorksheet.PivotTables.Add(
                        pivotTableWorksheet.Cells[NORTHWEST_CORNER_OF_PIVOT_TABLE], 
                        dataRange, 
                        "PivotTable");
    pivotTable.MultipleFieldFilters = true;
    pivotTable.GridDropZones = false;
    pivotTable.Outline = false;
    pivotTable.OutlineData = false;
    pivotTable.ShowError = true;
    pivotTable.ErrorCaption = "[error]";
    pivotTable.ShowHeaders = true;
    pivotTable.UseAutoFormatting = true;
    pivotTable.ApplyWidthHeightFormats = true;
    pivotTable.ShowDrill = true;

    // Row field[s]
    var descRowField = pivotTable.Fields["Description"];
    pivotTable.RowFields.Add(descRowField);

    // Column field[s]
    var monthYrColField = pivotTable.Fields["MonthYr"];
    pivotTable.ColumnFields.Add(monthYrColField);

    // Data field[s]
    var totQtyField = pivotTable.Fields["TotalQty"];
    pivotTable.DataFields.Add(totQtyField);

    var totPriceField = pivotTable.Fields["TotalPrice"];
    pivotTable.DataFields.Add(totPriceField);

    // Don't know how to calc these vals here, so had to put them on the data sheet
    var avgPriceField = pivotTable.Fields["AvgPrice"];
    pivotTable.DataFields.Add(avgPriceField);

    var prcntgOfTotalField = pivotTable.Fields["PrcntgOfTotal"];
    pivotTable.DataFields.Add(prcntgOfTotalField);

    // TODO: Get the sorting (by sales, descending) working:
    // These two lines don't seem that they would do so, but they do result in the items 
    // being sorted by (grand) total purchases descending
    //var fld = ((PivotField)pvt.PivotFields("Description"));
    //fld.AutoSort(2, "Total Purchases");
    //int dataCnt = pivotTable.ra //DataBodyRange.Columns.Count + 1;

    FormatPivotTable();
}

private void FormatPivotTable()
{
    int HEADER_ROW = 7;

    if (DateTimeFormatInfo.CurrentInfo != null)
        pivotTableWorksheet.Column(2).Style.Numberformat.Format = 
            DateTimeFormatInfo.CurrentInfo.YearMonthPattern;
    // Pivot Table Header Row - bold and increase height
    using (var headerRowFirstCell = pivotTableWorksheet.Cells[HEADER_ROW, 1])
    {
        headerRowFirstCell.Style.VerticalAlignment = ExcelVerticalAlignment.Center;
        headerRowFirstCell.Style.Font.Bold = true;
        headerRowFirstCell.Style.Font.Size = 12;
        pivotTableWorksheet.Row(HEADER_ROW).Height = 25;
    }

    ColorizeContractItemBlocks(contractItemDescs);
    // TODO: Why is the hiding not working?
    HideItemsWithFewerThan1PercentOfSales();
}

VDWWD VDWWD · Accepted Answer · 2016-10-28T13:44:54

You can use the build-in Date format YearMonthPattern. which would give september 2016 as format.

pivotTableWorksheet.Column(2).Style.Numberformat.Format = DateTimeFormatInfo.CurrentInfo.YearMonthPattern;

If you really want MMM yy as pattern, you need to overwrite the culture format:

Thread.CurrentThread.CurrentCulture = new CultureInfo("nl-NL")
{
    DateTimeFormat = { YearMonthPattern = "MMM yy" }
};
pivotTableWorksheet.Column(2).Style.Numberformat.Format = DateTimeFormatInfo.CurrentInfo.YearMonthPattern;

How can I change the format of the ColumnField column headings in EPPlus?

UPDATE

2 Answers