Objective
In this blog, I've explained how we can export large number of records in Excel file within very few seconds. I have implemented this solution in one of the project, where I need to export around 100,000 records in less than a minute.
Approach
- First step is to download the using NuGet Package with following command:
- It will add DocumentFormat.OpenXml.dll into your project:
- I had a situation where I was getting data in Generic List, So I converted Generic List to DataTable first. (Note: If you have all the records in DataTable itself, you don't need to execute below function!)
public static DataSet ToDataSet<T>(this IList<T> list)
{
Type elementType = typeof(T);
DataSet ds = new DataSet();
DataTable t = new DataTable();
ds.Tables.Add(t);
foreach(var propInfo in elementType.GetProperties())
{
Type ColType = Nullable.GetUnderlyingType(propInfo.PropertyType) ?? propInfo.PropertyType;
t.Columns.Add(propInfo.Name, ColType);
}
foreach (T item in list)
{
DataRow row = t.NewRow();
foreach (var propInfo in elementType.GetProperties())
{
row[propInfo.Name] = propInfo.GetValue(item, null) ?? DBNull.Value;
}
t.Rows.Add(row);
}
return ds;
}
- Now use below code to export the records in Excel file.
//Convert Generic List to DataSet
DataSet ds = ToDataSet(objList);
//Specify the column names which would be the Headers in Excel File when exported.
ds.Tables[0].Columns[0].ColumnName = "Account Name";
ds.Tables[0].Columns[1].ColumnName = "NAV Date";
ds.Tables[0].Columns[2].ColumnName = "NAV ₹";
var filename = ExportDataSet(ds);
return filename;
private static string ExportDataSet(DataSet ds)
{
string destination = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString() + ".xlsx");
using (var workbook = SpreadsheetDocument.Create(destination, DocumentFormat.OpenXml.SpreadsheetDocumentType.Workbook))
{
var workbookPart = workbook.AddWorkbookPart();
workbook.WorkbookPart.Workbook = new DocumentFormat.OpenXml.Spreadsheet.Workbook();
workbook.WorkbookPart.Workbook.Sheets = new DocumentFormat.OpenXml.Spreadsheet.Sheets();
foreach (System.Data.DataTable table in ds.Tables)
{
var sheetPart = workbook.WorkbookPart.AddNewPart<WorksheetPart>();
var sheetData = new DocumentFormat.OpenXml.Spreadsheet.SheetData();
sheetPart.Worksheet = new DocumentFormat.OpenXml.Spreadsheet.Worksheet(sheetData);
DocumentFormat.OpenXml.Spreadsheet.Sheets sheets = workbook.WorkbookPart.Workbook.GetFirstChild<DocumentFormat.OpenXml.Spreadsheet.Sheets>();
string relationshipId = workbook.WorkbookPart.GetIdOfPart(sheetPart);
uint sheetId = 1;
if (sheets.Elements<DocumentFormat.OpenXml.Spreadsheet.Sheet>().Count() > 0)
{
sheetId = sheets.Elements<DocumentFormat.OpenXml.Spreadsheet.Sheet>().Select(s =>s.SheetId.Value).Max() + 1;
}
DocumentFormat.OpenXml.Spreadsheet.Sheet sheet = new DocumentFormat.OpenXml.Spreadsheet.Sheet() { Id = relationshipId, SheetId = sheetId, Name = table.TableName };
sheets.Append(sheet);
DocumentFormat.OpenXml.Spreadsheet.Row headerRow = new DocumentFormat.OpenXml.Spreadsheet.Row();
List<String> columns = new List<string>();
foreach (System.Data.DataColumn column in table.Columns)
{
columns.Add(column.ColumnName);
DocumentFormat.OpenXml.Spreadsheet.Cell cell = new DocumentFormat.OpenXml.Spreadsheet.Cell();
cell.DataType = DocumentFormat.OpenXml.Spreadsheet.CellValues.String;
cell.CellValue = new DocumentFormat.OpenXml.Spreadsheet.CellValue(column.ColumnName);
headerRow.AppendChild(cell);
}
sheetData.AppendChild(headerRow);
foreach (System.Data.DataRow dsrow in table.Rows)
{
DocumentFormat.OpenXml.Spreadsheet.Row newRow = new DocumentFormat.OpenXml.Spreadsheet.Row();
foreach (String col in columns)
{
DocumentFormat.OpenXml.Spreadsheet.Cell cell = new DocumentFormat.OpenXml.Spreadsheet.Cell();
cell.DataType = DocumentFormat.OpenXml.Spreadsheet.CellValues.String;
cell.CellValue = new DocumentFormat.OpenXml.Spreadsheet.CellValue(dsrow[col].ToString());
newRow.AppendChild(cell);
}
sheetData.AppendChild(newRow);
}
}
}
return destination;
}
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