Creating Excel files directly on blob - azure-blob-storage

Question

I have following function which works fine when saving to disk. I am executing the code from an Azure function. Is there anyway to to write to a blob storage instead without saving to disk?
private void ExportDataSet(DataTable ds, string destination)
{
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();
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 = "Sites" };
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 ds.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 ds.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);
}
}
}
I would expect you maybe could save to a Stream?

Answer 1

Save to stream is the solution if you don't like to save it to a disk(In azure function, you can save it to a disk in azure function kudu like D:\home etc.).
If you choose to save to stream, just a few changes to your code, like below:
private void ExportDataSet(DataTable ds, MemoryStream memoryStream)
{
using (var workbook = SpreadsheetDocument.Create(memoryStream, DocumentFormat.OpenXml.SpreadsheetDocumentType.Workbook))
{
//your code logic here
}
//here, the code to upload to azure blob storage.
CloudStorageAccount storageAccount = new CloudStorageAccount(new StorageCredentials(accountName, accountKey), true);
CloudBlobClient cloudBlobClient = storageAccount.CreateCloudBlobClient();
CloudBlobContainer cloudBlobContainer = cloudBlobClient.GetContainerReference("test1");
CloudBlockBlob myblob = cloudBlobContainer.GetBlockBlobReference("myexcel.xlsx");
//upload to blob storage
memoryStream.Position = 0;
myblob.UploadFromStream(memoryStream)
//or you can use Asnyc mehtod like myblob.UploadFromStreamAsync(memoryStream)
}
Note: if you're using the latest azure blob storage sdk Microsoft.Azure.Storage.Blob, version 9.4.0 or later, you can use either UploadFromStreamAsync or UploadFromStream method in azure function v2.