OfficeOpenXml.Table.PivotTable.ExcelPivotTableField.SetCacheFieldNode C# (CSharp) Method

        internal void SetCacheFieldNode(XmlNode cacheField)
        {
            _cacheFieldHelper = new XmlHelperInstance(NameSpaceManager, cacheField);
            var groupNode = cacheField.SelectSingleNode("d:fieldGroup", NameSpaceManager);
            if (groupNode!=null)
            {
                var groupBy = groupNode.SelectSingleNode("d:rangePr/@groupBy", NameSpaceManager);
                if (groupBy==null)
                {
                    _grouping = new ExcelPivotTableFieldNumericGroup(NameSpaceManager, cacheField);
                }
                else
                {
                    DateGrouping=(eDateGroupBy)Enum.Parse(typeof(eDateGroupBy), groupBy.Value, true);
                    _grouping = new ExcelPivotTableFieldDateGroup(NameSpaceManager, groupNode);
                }
            }
        }

        private void AddCacheField(ExcelPivotTableField field, DateTime startDate, DateTime endDate, int interval)
        {
            //Add Cache definition field.
            var cacheTopNode   = _table.CacheDefinition.CacheDefinitionXml.SelectSingleNode("//d:cacheFields", _table.NameSpaceManager);
            var cacheFieldNode = _table.CacheDefinition.CacheDefinitionXml.CreateElement("cacheField", ExcelPackage.schemaMain);

            cacheFieldNode.SetAttribute("name", field.DateGrouping.ToString());
            cacheFieldNode.SetAttribute("databaseField", "0");
            cacheTopNode.AppendChild(cacheFieldNode);
            field.SetCacheFieldNode(cacheFieldNode);

            field.SetDateGroup(field.DateGrouping, startDate, endDate, interval);
        }