Phresco.FusionCharts.ListToXmlConverter.PrepareData C# (CSharp) Method

        public Plots PrepareData(string xValue, string yValue, GroupAction action)
        {
            // We first check that xValue and yValue are correct and throw an exception if needed
            if (!_items.List.Fields.ContainsField(xValue))
            {
                string message = "The column \"" + xValue + "\" does not exist in the list \"" + _items.List.Title + "\" or in the specified view \"" + _view.Title + "\".<br /><br />Check the view you specified and make sure that the column exists.";
                message += ListValidColumns();
                throw (new Exception(message));
            }
            if (yValue != String.Empty && !_items.List.Fields.ContainsField(yValue))
            {
                string message = "The column \"" + yValue + "\" does not exist in the list \"" + _items.List.Title + "\" or in the specified view \"" + _view.Title + "\".<br /><br />Check the view you specified and make sure that the column exists.";
                message += ListValidColumns();
                throw (new Exception(message));
            }

            // We prepare our output
            Plots plots = new Plots();

            // We loop through our SPList
            foreach (SPListItem item in _items)
            {
                // We get the X and Y from
                string x = "";
                try
                {
                    if (item[xValue] == null)
                        continue;

                    x = item[xValue].ToString();
                }
                catch
                {
                    throw (new Exception("The column \"" + xValue + "\" does not exist in the view"));
                }

                double y = 0;
                if (yValue != String.Empty) Double.TryParse(item[yValue].ToString(), out y);

                // The value is already in our array
                if (plots.Contains(x))
                {
                    int pos = plots.XIndexOf(x);

                    if (action == GroupAction.COUNT)
                    {
                        // Count, we add +1 to the existing value
                        plots.SetY(pos, Double.Parse(plots.GetY(pos).ToString()) + 1);
                    }
                    if (action == GroupAction.SUM)
                    {
                        // Sum, we add the value to the existing value
                        plots.SetY(pos, Double.Parse(plots.GetY(pos).ToString()) + y);
                    }
                    if (action == GroupAction.NOTHING)
                    {
                        // No action, we simply add the value
                        plots.Add(x, y);
                    }
                }
                else // The value is a new one in our array
                {
                    if (action == GroupAction.COUNT)
                    {
                        // Count, the first yValue is 1.
                        plots.Add(x, 1);
                    }
                    else
                    {
                        // anything else than Count, we just add the plot
                        plots.Add(x, y);
                    }
                }
            }
            return plots;
        }

        /// <summary>
        /// When the user click on the export to Excel button
        /// so we build a csv and then make it download with good header to make it opened by excel automatically
        /// </summary>
        protected void ExportExcelButtonClick(object sender, EventArgs e)
        {
            // We first check all settings
            CheckSettings();

            // We transform the list into XML Input
            ListToXmlConverter conv = new ListToXmlConverter(_listName, _viewName);

            // we build the csv string
            StringBuilder csv = new StringBuilder();

            csv.AppendLine(((XTitle != "") ? XTitle : "X") + ";" + ((YTitle != "") ? YTitle : "Y"));

            // We prepare the data in a nice hashtable
            Plots plots = conv.PrepareData(this._xValue, this._yValue, this._action);

            for (int i = 0; i < plots.Count(); i++)
            {
                csv.AppendLine(plots.GetX(i).Replace(",", " ").Replace(";", " ") + ";" + plots.GetY(i).ToString().Replace(",", " ").Replace(";", " "));
            }

            Context.Response.Clear();
            Context.Response.ContentType = "application/octet-stream";
            Context.Response.AddHeader("Content-Disposition", "attachment; filename=ExcelExport.csv");
            Context.Response.AddHeader("Content-Length", csv.Length.ToString());
            Context.Response.Write(csv.ToString());
            Context.Response.End();
        }