Accessing an open Excel Workbook in C#

Question

I need to access an excel file that is already open. I thought just inspecting the .Workbooks property that it would be there but it isn't. What is the right way to get a reference to the open workbook?

var app = new Microsoft.Office.Interop.Excel.Application();

// the count is 0 =(
app.Workbooks.Count == 0;

EDIT

I can get a reference to the Excel Application via...

app = (Excel.Application)Marshal.GetActiveObject("Excel.Application");

but app.Workbooks.Count is still 0 why isn't it able to get a reference to the opened workbook?

Answer 1

Instead of instantiating a new instance, check for an existing one:

try
{
  Microsoft.Office.Interop.Excel.Application app = 
      System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");
}
catch
{
  // Excel is not running.
}

Answer 2

 String constr = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source="+txtSourceFile.Text+";Extended Properties='Excel 8.0;HDR=YES;';";
        String constr2 = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + txtLibrary.Text + ";Extended Properties='Excel 8.0;HDR=YES;';";

        OleDbConnection con = new OleDbConnection(constr);
        OleDbConnection con2 = new OleDbConnection(constr2);
        OleDbConnection con3 = new OleDbConnection(constr);

        OleDbCommand oconn = new OleDbCommand("Select * From [eudra$]", con);
        OleDbCommand oconn2 = new OleDbCommand("Select * From [Sheet1$]", con2);
        OleDbCommand oconn3 = new OleDbCommand("Select * From [eudra$] where EXAMPARM in ('with one or more serious adverse events','with one or more non-serious adverse events that met the incidence cutoff')", con);

        if (txtSourceFile.Text != "")
        {
            con.Open();
            con2.Open();
            con3.Open();

            OleDbDataAdapter sda = new OleDbDataAdapter(oconn);
            OleDbDataAdapter sda2 = new OleDbDataAdapter(oconn2);
            OleDbDataAdapter sda3 = new OleDbDataAdapter(oconn3);


            DataTable data = new DataTable();
            sda.Fill(data);

            DataTable data2 = new DataTable();
            sda2.Fill(data2);

            DataTable data3 = new DataTable();
            sda3.Fill(data3);

            var test = JoinDataTables(data, data2, (row1, row2) => (row1.Field<string>("BODY_SYS").ToUpper() == row2.Field<string>("Term").ToUpper() ));

            data3.Merge(test, true);

            dgvImp.DataSource = data3;
            con.Close();
        }

Answer 3

Try this code:

using Excel = Microsoft.Office.Interop.Excel;

public Excel.Application xlApp;
public Excel.Workbook xlWorkBook;
public Excel.Worksheet xlWorkSheet;

public void ExcelTransferData()
{
   xlApp = new Microsoft.Office.Interop.Excel.Application();
   xlApp = (Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");

   foreach (Excel.Workbook item in xlApp.Workbooks)
   {
        //Select the excel target 'NAME'
        if (item.Name == "Template.xlsx")
        {
            xlWorkBook = item; 
            break;
        }

        //Select the target workbook
        xlWorkSheet = xlWorkBook.Sheets[1] as Excel.Worksheet;
        //Set cell value
        xlWorkSheet.Cells[5, 1] = "davinceleecode";
   }
}

Answer 4

// creating Excel Application
Microsoft.Office.Interop.Excel._Application app = new Microsoft.Office.Interop.Excel.Application();

// creating new WorkBook within Excel application
Microsoft.Office.Interop.Excel._Workbook workbook = app.Workbooks.Add(Type.Missing);

// creating new Excelsheet in workbook
Microsoft.Office.Interop.Excel._Worksheet worksheet = null;

// see the excel sheet behind the program
app.Visible = true;

// get the reference of first sheet. By default its name is Sheet1.
// store its reference to worksheet
worksheet = workbook.Sheets["Sheet1"];
worksheet = workbook.ActiveSheet;

// changing the name of active sheet
worksheet.Name = "Exported from gridview";

try
{
    // storing header part in Excel
    for (int i = 1; i < dgvRESULTS.Columns.Count + 1; i++)
    {
        worksheet.Cells[1, i] = dgvRESULTS.Columns[i - 1].HeaderText;
        worksheet.Cells[1, i].Interior.Color = System.Drawing.Color.LightYellow;
    }

    // storing Each row and column value to excel sheet
    for (int i = 0; i < dgvRESULTS.Rows.Count - 1; i++)
    {
        for (int j = 0; j < dgvRESULTS.Columns.Count; j++)
        {
            if (dgvRESULTS.Rows[i].Cells[j].Value != null)
            {
                worksheet.Cells[i + 2, j + 1] = dgvRESULTS.Rows[i].Cells[j].Value.ToString();
                //worksheet.Cells[i + 2, j + 1].Interior.Color = System.Drawing.ColorTranslator.ToOle(dgvRESULTS.Rows[i].DefaultCellStyle.BackColor);
            }
            else
            {
                worksheet.Cells[i + 2, j + 1] = "";
            }
        }
    }
}
catch(NullReferenceException ne)
{
}
string filePath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
// save the application
workbook.SaveAs(filePath +"\\output.xls", Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlExclusive, Type.Missing, Type.Missing, Type.Missing, Type.Missing);

// Exit from the application
app.Quit();