How to retrieve column names from a excel sheet? - linq

Question

Using EPPlus I'm writing data to multiple sheets. If a sheet is not created I'm adding a sheet else I'm retrieving the used rows and adding data from that row and saving it
FileInfo newFile = new FileInfo("Excel.xlsx");
using (ExcelPackage xlPackage = new ExcelPackage(newFile))
{
var ws = xlPackage.Workbook.Worksheets.FirstOrDefault(x => x.Name == language.Culture);
if (ws == null)
{
worksheet = xlPackage.Workbook.Worksheets.Add(language.Culture);
//writing data
}
else
{
worksheet = xlPackage.Workbook.Worksheets[language.Culture];
colCount = worksheet.Dimension.End.Column;
rowCount = worksheet.Dimension.End.Row;
//write data
}
worksheet.Cells[worksheet.Dimension.Address].AutoFitColumns();
xlPackage.Save();
And it is working great.
Now I want to retrieve the column names of each sheet in the excel using LinqToExcel and this is my code
string sheetName = language.Culture;
var excelFile = new ExcelQueryFactory(excelPath);
IQueryable<Row> excelSheetValues = from workingSheet in excelFile.Worksheet(sheetName) select workingSheet;
string[] headerRow = excelFile.GetColumnNames(sheetName).ToArray();
At header row it is throwing me an exception
An OleDbException exception was caught
External table is not in the expected format.
But I don't want to use Oledb and want to work with Linq To Excel.
Note: When I'm working with single sheet rather than multiple sheets
it is working fine and retrieving all columns. Where am I going wrong.

Answer 1

(Based on OP's Comments)
The AutoFitColumn function has always been a little touchy. The important thing to remember is to call it AFTER you load the cell data.
But if you want a use a minimum width (when columns are very narrow and you want to use a minimum) I find EPP to be unreliable. It seems to always use DefualtColWidth of the worksheet even if you pass in a minimumWidth to one of the function overloads.
Here is how I get around it:
[TestMethod]
public void Autofit_Column_Range_Test()
{
//http://stackoverflow.com/questions/31165959/how-to-retrieve-column-names-from-a-excel-sheet
//Throw in some data
var datatable = new DataTable("tblData");
datatable.Columns.Add(new DataColumn("Nar", typeof(int))); //This would not be autofitted without the workaround since the default width of a new ws, usually 8.43
datatable.Columns.Add(new DataColumn("Wide Column", typeof(int)));
datatable.Columns.Add(new DataColumn("Really Wide Column", typeof(int)));
for (var i = 0; i < 20; i++)
{
var row = datatable.NewRow();
row[0] = i;
row[1] = i * 10;
row[2] = i * 100;
datatable.Rows.Add(row);
}
var existingFile2 = new FileInfo(#"c:\temp\temp.xlsx");
if (existingFile2.Exists)
existingFile2.Delete();
using (var package = new ExcelPackage(existingFile2))
{
//Add the data
var ws = package.Workbook.Worksheets.Add("Sheet1");
ws.Cells.LoadFromDataTable(datatable, true);
//Keep track of the original default of 8.43 (excel default unless the user has changed it in their local Excel install)
var orginaldefault = ws.DefaultColWidth;
ws.DefaultColWidth = 15;
//Even if you pass in a miniumWidth as the first parameter like '.AutoFitColumns(15)' EPPlus usually ignores it and goes with DefaultColWidth
ws.Cells[ws.Dimension.Address].AutoFitColumns();
//Set it back to what it was so it respects the user's local setting
ws.DefaultColWidth = orginaldefault;
package.Save();
}
}