Develop Reference

C# Error: Microsoft Excel cannot access the file '...'. There are several possible reasons

I've developed an ASP.Net MVC application, that is running on a IIS sever. I've wrote a code that reads a CSV and insert the rows of it in a database.
[HttpPost]
public ActionResult InsertPosition(int id, HttpPostedFileBase position)
{
var posicoesExistentes = db.tbPositions.Where(s => s.id_unique == id).AsEnumerable();
foreach (tbPosition posicao in posicoesExistentes)
{
db.tbPositions.Remove(posicao);
}
if (!Directory.Exists(Server.MapPath("~/App_Data/")))
{
System.IO.Directory.CreateDirectory(Server.MapPath("~/App_Data/"));
}
string excelPath = Server.MapPath("~/App_Data/" + position.FileName);
if (System.IO.File.Exists(excelPath))
{
System.IO.File.Delete(excelPath);
}
position.SaveAs(excelPath);
string tempPath = Server.MapPath("~/App_Data/" + "tmp_" + position.FileName);
System.IO.File.Copy(excelPath, tempPath, true);
Excel.Application application = new Excel.Application();
Excel.Workbook workbook = application.Workbooks.Open(tempPath, ReadOnly: true,Editable:false);
Excel.Worksheet worksheet = workbook.ActiveSheet;
Excel.Range range = worksheet.UsedRange;
application.Visible = true;
for (int row = 1; row < range.Rows.Count - 1; row++)
{
tbPosition p = new tbPosition();
p.position = (((Excel.Range)range.Cells[row, 1]).Text == "") ? null : Convert.ToInt32(((Excel.Range)range.Cells[row, 1]).Text);
p.left = ((Excel.Range)range.Cells[row, 2]).Text;
p.right = ((Excel.Range)range.Cells[row, 3]).Text;
p.paper = ((Excel.Range)range.Cells[row, 4]).Text;
p.denomination = ((Excel.Range)range.Cells[row, 5]).Text;
p.material = ((Excel.Range)range.Cells[row, 6]).Text;
p.norme = ((Excel.Range)range.Cells[row, 7]).Text;
p.finalized_measures = ((Excel.Range)range.Cells[row, 8]).Text;
p.observation = ((Excel.Range)range.Cells[row, 9]).Text;
p.id_unique = id;
db.tbPositions.Add(p);
db.SaveChanges();
}
workbook.Close(true, Type.Missing, Type.Missing);
application.Quit();
System.IO.File.Delete(tempPath);
return Json("Success", JsonRequestBehavior.AllowGet);
}
but in return I got the error ' Microsoft Excel cannot access the file '...'. There are several possible reasons' when I try to open the requested excel file.
I've already tried to open the file as readonly, I've already tried to give permissions to the specifieds folders, multiples ways of close the excel file, and create an copy file of the original and read him. But unsuccessful in each one of these solutions. What have I missed here?

Unsupported
The short answer is that trying to programatically manipulate an Excel document using the Automation API is not supported outside of a UI context. You will come across all sorts of frustrations (for example, the API is permitted to show dialogs - how are you going to click on "OK" if it's running on a web-server?).
Microsoft explicitly state this here
Microsoft does not recommend or support server-side Automation of Office.
So what do I use?
I would recommend using the OpenXML SDK - this is free, fully supported and much faster than the Automation API.
Aspose also has a set of products, but they are not free, and I've not used them.
But I HAVE to do it this way
However, if you absolutely have to use the COM API then the following might help you:
HERE BE DRAGONS
The big problem with automation in Excel is that you need to ensure you close every single reference whenever you use them (by calling ReleaseComObject on it).
For example, the following code will cause Excel to stay open:
var range;
range = excelApplication.Range("A1");
range = excelApplication.Range("A2");
System.Runtime.InteropServices.Marshal.ReleaseComObject(range)
range = Nothing
This is because there is still a reference left over from the call to get range "A1".
Therefore, I would recommend writing a wrapper around the Excel class so that any access to, e.g., a range frees any previous ranges accessed before accessing the new range.
For reference, here is the code I used to release COM objects in the class I wrote:
Private Sub ReleaseComObject(ByVal o As Object)
Try
If Not IsNothing(o) Then
While System.Runtime.InteropServices.Marshal.ReleaseComObject(o) > 0
'Wait for COM object to be released.'
End While
End If
o = Nothing
Catch exc As System.Runtime.InteropServices.COMException
LogError(exc) ' Suppress errors thrown here '
End Try
End Sub

Try this
protected void ImportCSV(object sender, EventArgs e)
{
importbtn();
}
public class Item
{
public Item(string line)
{
var split = line.Split(',');
string FIELD1 = split[0];
string FIELD2 = split[1];
string FIELD3 = split[2];
string mainconn = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
using (SqlConnection con = new SqlConnection(mainconn))
{
using (SqlCommand cmd = new SqlCommand("storedProcedureName", con))
{
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#FIELD1", SqlDbType.VarChar).Value = FIELD1;
cmd.Parameters.AddWithValue("#FIELD2", SqlDbType.VarChar).Value = FIELD2;
cmd.Parameters.AddWithValue("#FIELD3", SqlDbType.VarChar).Value = FIELD3;
con.Open();
cmd.ExecuteNonQuery();
}
}
}
}
private void importbtn()
{
try
{
string csvPath = Server.MapPath("~/Files/") + Path.GetFileName(FileUpload1.PostedFile.FileName);
FileUpload1.SaveAs(csvPath);
var listOfObjects = File.ReadLines(csvPath).Select(line => new Item(line)).ToList();
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[3] { new DataColumn("FIELD1", typeof(string)),
new DataColumn("FIELD2", typeof(string)),
new DataColumn("FIELD3",typeof(string)) });
string csvData = File.ReadAllText(csvPath);
foreach (string row in csvData.Split('\n'))
{
if (!string.IsNullOrEmpty(row))
{
dt.Rows.Add();
int i = 0;
//Execute a loop over the columns.
foreach (string cell in row.Split(','))
{
dt.Rows[dt.Rows.Count - 1][i] = cell;
i++;
}
}
}
GridView1.DataSource = dt;
GridView1.DataBind();
Label1.Text = "File Attached Successfully";
}
catch (Exception ex)
{
Message.Text = "Please Attach any File" /*+ ex.Message*/;
}
}

User input to change column header text in DataGrid

I am creating a DataGrid by importing an excel file. I want users manually to be able to change column names from the application.
Edit: Workaround at the bottom
My desktop app will have below logic:
Load excel file and display table in DataGrid
Manually change Column names to match fixed text. (e.x. Column "PricesZZZ" renamed to "Prices", "LeadTimeXXX to "LeadTime")
Export DataGrid to new excel template with only relevant columns that are matched by fixed text (thus the need to have correct
names).
Excel file can have multiple columns and only several of those columns have relevant information and the only way to identify them is to match header name or some other way have user "tell" program which column holds which information.
I need to find a way to change Column name based on user input as I think it's most straightforward. I'm new to c# so sorry if my thinking is a little backwards.
Below is the code snippet I have so far. Might not be relevant for this specific problem, but may help visualize. I use EPPlus library
Import excel
private void btnOpenXL_Click(object sender, RoutedEventArgs e)
{
// Create OpenFileDialog
Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();
// Set filter for file extension and default file extension
dlg.DefaultExt = ".xls";
dlg.Filter = "Excel Files|*.xlsx;*.xls;*.xlsm;*.csv";
// Display OpenFileDialog by calling ShowDialog method
Nullable<bool> result = dlg.ShowDialog();
// Get the selected file name
if (result == true)
{
// Open document
string filename = dlg.FileName;
//call another class to draw the table
dataGrid.ItemsSource = GetDataTableFromExcel(filename).DefaultView;
MessageBox.Show("import done");
}
}
public static DataTable GetDataTableFromExcel(string path, bool hasHeader = true)
{
using (var pck = new OfficeOpenXml.ExcelPackage())
{
using (var stream = File.OpenRead(path))
{
pck.Load(stream);
}
var ws = pck.Workbook.Worksheets.First();
DataTable tbl = new DataTable();
foreach (var firstRowCell in ws.Cells[1, 1, 1, ws.Dimension.End.Column])
{
tbl.Columns.Add(hasHeader ? firstRowCell.Text : string.Format("Column {0}", firstRowCell.Start.Column));
}
var startRow = hasHeader ? 2 : 1;
for (int rowNum = startRow; rowNum <= ws.Dimension.End.Row; rowNum++)
{
var wsRow = ws.Cells[rowNum, 1, rowNum, ws.Dimension.End.Column];
DataRow row = tbl.Rows.Add();
foreach (var cell in wsRow)
{
row[cell.Start.Column - 1] = cell.Text;
}
}
return tbl;
}
}
Export excel
private void btnExportToXL_Click(object sender, RoutedEventArgs e)
{
DataTable dataTable = new DataTable();
dataTable = ((DataView)dataGrid.ItemsSource).ToTable();
ExportDataTableToExcel(dataTable);
MessageBox.Show("export done");
}
public void ExportDataTableToExcel(DataTable dataTable)
{
string path = "C:\\test";
var newFile = new FileInfo(path + "\\" +
DateTime.Now.Ticks + ".xlsx");
using (ExcelPackage pck = new ExcelPackage(newFile))
{
ExcelWorksheet ws = pck.Workbook.Worksheets.Add("Sheet1");
ws.Cells["A1"].LoadFromDataTable(dataTable, true);
pck.Save();
System.Diagnostics.Process.Start(newFile.ToString());
}
}
EDIT:
Workaround by double clicking on any cell in datagrid:
private void dataGrid_MouseDoubleClick(object sender, RoutedEventArgs e)
{
if (dataGrid.SelectedIndex == -1) //if column selected, cant use .CurrentColumn property
{
MessageBox.Show("Please double click on a row");
}
else
{
DataGridColumn columnHeader = dataGrid.CurrentColumn;
if (columnHeader != null)
{
string input = Interaction.InputBox("Title", "Prompt", "Default", 0, 0);
columnHeader.Header = input;
}
}
}

You can change the column names of the datagridview. But note, that this change is limited only to the grid and not it's data source. So in a nutshell, for simple representational purposes, you can use the following code:
dataGrid.Columns[i].HeaderText = "New Column Name"; //i is the index of the column
You can call this code form a Button click event of a Text change event of the input where the user provides the header name. Additionally, if you have the column names beforehand, you can replace then column headers with new values right after the data source has been bound to the grid. Change the headers after this line:
dataGrid.ItemsSource = GetDataTableFromExcel(filename).DefaultView;
//Set new column names here

export data from CSV to datatable in c#

I am using below code to export data from a csv file to datatable.
As the values are of mixed text i.e. both numbers and Alphabets, some of the columns are not getting exported to Datatable.
I have done some research here and found that we need to set ImportMixedType = Text and TypeGuessRows = 0 in registry which even did not solve the problem.
Below code is working for some files even with mixed text.
Could someone tell me what is wrong with below code. Do I miss some thing here.
if (isFirstRowHeader)
{
header = "Yes";
}
using (OleDbConnection connection = new OleDbConnection(#"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + pathOnly +
";Extended Properties=\"text;HDR=" + header + ";FMT=Delimited\";"))
{
using (OleDbCommand command = new OleDbCommand(sql, connection))
{
using (OleDbDataAdapter adapter = new OleDbDataAdapter(command))
{
adapter.Fill(table);
}
connection.Close();
}
}

for comma delimited file this worked for me
public DataTable CSVtoDataTable(string inputpath)
{
DataTable csvdt = new DataTable();
string Fulltext;
if (File.Exists(inputpath))
{
using (StreamReader sr = new StreamReader(inputpath))
{
while (!sr.EndOfStream)
{
Fulltext = sr.ReadToEnd().ToString();//read full content
string[] rows = Fulltext.Split('\n');//split file content to get the rows
for (int i = 0; i < rows.Count() - 1; i++)
{
var regex = new Regex("\\\"(.*?)\\\"");
var output = regex.Replace(rows[i], m => m.Value.Replace(",", "\\c"));//replace commas inside quotes
string[] rowValues = output.Split(',');//split rows with comma',' to get the column values
{
if (i == 0)
{
for (int j = 0; j < rowValues.Count(); j++)
{
csvdt.Columns.Add(rowValues[j].Replace("\\c",","));//headers
}
}
else
{
try
{
DataRow dr = csvdt.NewRow();
for (int k = 0; k < rowValues.Count(); k++)
{
if (k >= dr.Table.Columns.Count)// more columns may exist
{ csvdt .Columns.Add("clmn" + k);
dr = csvdt .NewRow();
}
dr[k] = rowValues[k].Replace("\\c", ",");
}
csvdt.Rows.Add(dr);//add other rows
}
catch
{
Console.WriteLine("error");
}
}
}
}
}
}
}
return csvdt;
}

The main thing that would probably help is to first stop using OleDB objects for reading a delimited file. I suggest using the 'TextFieldParser' which is what I have successfully used for over 2 years now for a client.
http://www.dotnetperls.com/textfieldparser
There may be other issues, but without seeing your .CSV file, I can't tell you where your problem may lie.
The TextFieldParser is specifically designed to parse comma delimited files. The OleDb objects are not. So, start there and then we can determine what the problem may be, if it persists.
If you look at an example on the link I provided, they are merely writing lines to the console. You can alter this code portion to add rows to a DataTable object, as I do, for sorting purposes.

How to fit the columns in an excel sheet

I'm writing a list to an excel sheet generated using EPPlus with .xlsx extension. Then using worksheet.Cells[worksheet.Dimension.Address].AutoFitColumns(); method I tried to fit the columns.
This is how I write data
using (ExcelPackage xlPackage = new ExcelPackage(newFile))
{
System.Data.DataTable dt = new System.Data.DataTable();
var ws = xlPackage.Workbook.Worksheets.FirstOrDefault(x => x.Name == language.Culture);
if (ws == null)
{
int i = 1, j = 0;
worksheet = xlPackage.Workbook.Worksheets.Add(language.Culture);
foreach (ExcelFields fieldValues in UnmatchedFieldList)
{
//code
}
else
{
int i = 0;
worksheet = xlPackage.Workbook.Worksheets[language.Culture];
colCount = worksheet.Dimension.End.Column;
rowCount = worksheet.Dimension.End.Row;
foreach (ExcelFields fieldValues in UnmatchedFieldList)
{
worksheet.Cells[rowCount + 1, count + 1].Value = itemName;
}
worksheet.Cells[worksheet.Dimension.Address].AutoFitColumns();
xlPackage.Save();
}
I read data as
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 headerRow it is throwing the below error
When I'm trying to read the data from excel it is throwing an exception
External table is not in the expected format
I found out,this is due to the columns are not formatted(width) correctly. When I manually set the columns width by double clicking the cell and run the code it is working fine
So I want to achieve this using code

External table is not in the expected format exception is occurred because of exception of connection string so there fore check your connection string with following sample
public static string docPath= #"C:\sourcefolder\myfile.xlsx";
public static string ConnectionString= "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + docPath + ";Extended Properties=Excel 12.0;";
or if you use LinqToExcel then check whether you have set setting the DatabaseEngine property like as follows
public string docPath= #"C:\sourcefolder\myfile.xlsx";
var excelFile = new ExcelQueryFactory(docPath);
excelFile.DatabaseEngine = DatabaseEngine.Ace;

SSIS and The Excel Files Saga

I have a Excel File (xls) that has a column called Money. In the Money column all the columns are formatted as number, except for some that have that marker saying formatted as text against them. I convert the Excel file to CSV using a c# script that uses IMEX=1 in the connection string to open it. The fields that are marked with stored as text do not come through to the csv file. The file is large, about 20MB. So this means 100 values like 33344 etc do not come thro the csv file.
I tried to put a delay in where I open the Excel File. This worked on my PC but not the Development machine.
Have any idea how to get round this without manually intervention, like format all columns with mixed data types as number etc ? I am looking for an automated solution that works every time . This is on SSIS 2008.
static void ConvertExcelToCsv(string excelFilePath, string csvOutputFile, int worksheetNumber = 1) {
if (!File.Exists(excelFilePath)) throw new FileNotFoundException(excelFilePath);
if (File.Exists(csvOutputFile)) throw new ArgumentException("File exists: " + csvOutputFile);
// connection string
var cnnStr = String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=\"Excel 8.0;IMEX=1;HDR=NO\"", excelFilePath);
var cnn = new OleDbConnection(cnnStr);
// get schema, then data
var dt = new DataTable();
try {
cnn.Open();
var schemaTable = cnn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
if (schemaTable.Rows.Count < worksheetNumber) throw new ArgumentException("The worksheet number provided cannot be found in the spreadsheet");
string worksheet = schemaTable.Rows[worksheetNumber - 1]["table_name"].ToString().Replace("'", "");
string sql = String.Format("select * from [{0}]", worksheet);
var da = new OleDbDataAdapter(sql, cnn);
da.Fill(dt);
}
catch (Exception e) {
// ???
throw e;
}
finally {
// free resources
cnn.Close();
}
// write out CSV data
using (var wtr = new StreamWriter(csvOutputFile)) {
foreach (DataRow row in dt.Rows) {
bool firstLine = true;
foreach (DataColumn col in dt.Columns) {
if (!firstLine) { wtr.Write(","); } else { firstLine = false; }
var data = row[col.ColumnName].ToString().Replace("\"", "\"\"");
wtr.Write(String.Format("\"{0}\"", data));
}
wtr.WriteLine();
}
}
}

My solution was to specify a format for the incoming files which said no columns with mixed data types. Solution was from business side and not technology.