ASP.NET MapPath Resolves Virtual, Physical Paths (path)

 

You need to use MapPath to resolve virtual paths and physical paths. You run the ASP.NET development server on your local machine, but the paths on it are not the same as they are on your server. Here we use MapPath to find physical paths and file locations, using the C# programming language.

Introduction

First, in ASP.NET the ~ tilde indicates the root of a virtual path. We need the tilde because otherwise ASP.NET can't figure out if a path is absolute or relative. Let's look at some virtual paths and what they might map to.

Virtual paths

~/App_Data/Sample.xml
~/
~/Map.txt

Physical paths

C:\Website\Files\Sample.xml
C:\Website\Default.aspx
C:\Website\Map.txt

Use MapPath method

You can call MapPath in any C# file in your ASP.NET website. You may want to include the System.Web namespace first, but this is not required. Make sure you are looking at a C# file in your ASP.NET project and then add some code that looks similar to parts of the following.

Example code that uses MapPath [C#]

using System;
using System.Web;

/// <summary>
/// This is an example code-behind file you can put in App_Code.
/// It shows examples of using MapPath in code-behind easily.
/// </summary>
public class Example
{
    public Example()
    {
	// This will locate the Example.xml file in the App_Data folder.
	// ... (App_Data is a good place to put data files.)
	string a = HttpContext.Current.Server.MapPath("~/App_Data/Example.xml");

	// This will locate the Example.txt file in the root directory.
	// ... This can be used in a file in any directory in the application.
	string b = HttpContext.Current.Request.MapPath("~/Example.txt");
    }
}

Using Server.MapPath. Here we note that the Server.MapPath does the same thing as the Request.MapPath method. In this example, the two versions will do the same thing. There may be some differences in different usage scenarios, but in those cases a more detailed guide would be helpful. The two methods are interchangeable in most ASP.NET projects.