在.ashx页面中使用文件的相对路径

Question

Double apologies - first, I'm completely new to ASP.net so I'm sure that this is a very naive question, and second, it looks like there's already a hundred questions on SO about relative paths in ASP.NET. Unfortunately - I can't find one that answers my question.

Background - I'm working on an .ashx file that needs to be able to access an Excel file.

When I'm running locally and using an absolute path to the file, everything works great. Here's my code:

<%@ WebHandler Language="C#" Class="MyHandler" %>
using System;
... [a bunch more "usings..."]
using Microsoft.Office.Interop.Excel;

public class MyHandler : IHttpHandler {
    public void ProcessRequest(HttpContext context) {
        string path = @"C:\Users\[...]\myExcelFile.xls";
        Workbook theWorkbook;
        Microsoft.Office.Interop.Excel.Application app = new Microsoft.Office.Interop.Excel.Application();
        theWorkbook = app.Workbooks.Open(path);

However, I want to run this on a server, and use a relative path to the myExcelFile.xls .

My project is set up like this:

Main folder:
 - Default.aspx
 - myExcelFile.xls
 - Web.config
 - Global.asax
Styles folder
Scripts folder
Handler folder
 - MyHandler.ashx (that's reading the Excel File)
bin folder

So - you can see that the Excel file is in the "root" of the application.

To make the path relative, I've tried the following with no success:

Assuming that "relative" is from myHandler.ashx:

string path = @"..\myExcelFile.xls":

Assuming that ~ refers to the "root":

string path = @"~\myExcelFile.xls";

Just guessing:

string path = @".\myExcelFile.xls";

Just desperate:

string path = "myExcelFile.xls";

None of these worked.

So I did a little research here on SO, and found System.IO.Path.GetFullPath . So I tried:

string path = System.IO.Path.GetFullPath("myExcelFile.xls");

That didn't work, but at least I could see that the value of path was C:\\Program Files (x86)\\Common Files\\Microsoft Shared\\DevServer\\11.0\\PinpointTool-DC.xls

Of course - I don't understand that at all - that path is nowhere near where my project is (which means I don't understand what System.IO.Path.GetFullPath does...)

Last, I tried Server.MapPath("myExcelFile.xls") , but that doesn't work at all (locally, at least):

Compiler Error Message: CS0103: The name 'Server' does not exist in the current context

So, how can I get this to work (ideally both locally and on a server?)

Answer 1

While you could use context.Server.MapPath , You could also use a path that you define in your "web.config" file in the appSettings section and read it later in your application:

Web.config:

...
<appSettings>
    <add key="myBasePath" value="C:\Some\Path" />
</appSettings>
...

In your ASHX handler you could write something like:

...
string path = Path.Combine(
    ConfigurationManager.AppSettings[@"myBasePath"],
    @"myExcelFile.xls");
...

You can (and should) have different "web.config" files for your development machine and your production environment.

To second John Saunders' remark regarding Office Interop on the server , I strongly recommend to use a decidated library like

• Aspose.Cells or
• Spire.XLS

I worked successfully with both of them (commerical, though).

Answer 2

have you tried

System.IO.Path.Combine(HttpContext.Current.Server.MapPath("~/."),"myExcelFile.xls");

Hope this will help