Interop word application Error in c#

Question

I need help with this script. I'm using Word Interop but I get the following error, why?

thanks.

The Error

Object reference not set to an instance of an object. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

     catch (Exception ex)
     {
         oDoc.Close(ref o, ref o, ref o);
         ClientScript.RegisterStartupScript(this.GetType(), "error Kobie Williams", "javascript:;alert('" + ex.Message + "')");
   }

In Line

oDoc.Close(ref o, ref o, ref o);

.CS

using System;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //creating instance of word application
        Microsoft.Office.Interop.Word._Application w = new Microsoft.Office.Interop.Word.Application();
        object path = @"C:\inetpub\wwwroot\WebSite1\Kobie_Williams\id.docx";
        object read = "ReadWrite";
        object readOnly = false;
        object o = System.Reflection.Missing.Value;

        //opening document
        Microsoft.Office.Interop.Word._Document oDoc = w.Documents.Open(ref path, ref o, ref readOnly, ref o, ref o, ref o, ref o, ref o, ref o, ref o, ref o, ref o, ref o, ref o, ref o, ref o);

        try
        {
            //loop for each paragraph in document
            foreach (Microsoft.Office.Interop.Word.Paragraph p in oDoc.Paragraphs)
            {
                Microsoft.Office.Interop.Word.Range rng = p.Range;
                Microsoft.Office.Interop.Word.Style styl = rng.get_Style() as Microsoft.Office.Interop.Word.Style;
                //checking if document containg table
                if ((bool)rng.get_Information(Microsoft.Office.Interop.Word.WdInformation.wdWithInTable)
                                    == true)
                {
                    //loop for each cell in table
                    foreach (Microsoft.Office.Interop.Word.Cell c in rng.Cells)
                    {
                        if (rng.Cells.Count > 0)
                        {
                            //checking for desired field in table
                            if (c.Range.Text.ToString().Contains("ID"))
                                //editing values in tables.
                                c.Next.Range.Text = "1";
                            if (c.Range.Text.ToString().Contains("Name"))
                                c.Next.Range.Text = "Haider";
                            if (c.Range.Text.ToString().Contains("Address"))
                                c.Next.Range.Text = "Kobie-Williams";
                        }
                    }
                    //saving document
                    oDoc.Save();
                }
            }
            //closing document
            oDoc.Close(ref o, ref o, ref o);
        }
        catch (Exception ex)
        {
            oDoc.Close(ref o, ref o, ref o);
            ClientScript.RegisterStartupScript(this.GetType(), "error Kobie Williams", "javascript:;alert('" + ex.Message + "')");
        }

    }

Answer 1

It's likely oDoc is null because the file failed to load on w.Documents.Open(). You need to do something like

if (oDoc != null)
    oDoc.Close()

Also, this should be done only once in the finally block, not repeated in both the try and catch blocks.

Also, using Office Interop is generally a bad idea on web servers: Is Microsoft.Office.Interop safe to use for (file-converting) for a website?