C# getting the path of %AppData%

423
votes

C# 2008 SP1

I am using the code below:

dt.ReadXml("%AppData%\\DateLinks.xml");

However, I am getting an exception that points to the location of where my application is running from:

Could not find a part of the path 'D:\Projects\SubVersionProjects\CatDialer\bin\Debug\%AppData%\DateLinks.xml'.

I thought the %AppData% should find the relative path. When I go Start|Run|%AppData% windows explorer takes me to that directory.

I can not put the full path in, as the user is different on each client machine.

10
c#.netpath

10 Answers

878
votes

To get the AppData directory, it's best to use the GetFolderPath method:

Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)

(must add using System if not present).

%AppData% is an environment variable, and they are not automatically expanded anywhere in .NET, although you can explicitly use the Environment.ExpandEnvironmentVariable method to do so. I would still strongly suggest that you use GetFolderPath however, because as Johannes Rössel points out in the comment, %AppData% may not be set in certain circumstances.

Finally, to create the path as shown in your example:

var fileName = Path.Combine(Environment.GetFolderPath(
    Environment.SpecialFolder.ApplicationData), "DateLinks.xml");
51
votes

The path is different if you're talking ASP.NET.

I couldn't find any of the 'SpecialFolder' values that pointed to /App_Data for ASP.NET.

Instead you need to do this:

 HttpContext.Current.ApplicationInstance.Server.MapPath("~/App_Data")

(Note: You don't need the 'Current' property in an MVC Controller)

If theres another more 'abstract' way to get to App_Data would love to hear how.

49
votes

The BEST way to use the AppData directory, IS to use Environment.ExpandEnvironmentVariables method.

Reasons:

  • it replaces parts of your string with valid directories or whatever
  • it is case-insensitive
  • it is easy and uncomplicated
  • it is a standard
  • good for dealing with user input

Examples:

string path;
path = @"%AppData%\stuff";
path = @"%aPpdAtA%\HelloWorld";
path = @"%progRAMfiLES%\Adobe;%appdata%\FileZilla"; // collection of paths

path = Environment.ExpandEnvironmentVariables(path);
Console.WriteLine(path);

More info:

%ALLUSERSPROFILE%   C:\ProgramData
%APPDATA%   C:\Users\Username\AppData\Roaming
%COMMONPROGRAMFILES%    C:\Program Files\Common Files
%COMMONPROGRAMFILES(x86)%   C:\Program Files (x86)\Common Files
%COMSPEC%   C:\Windows\System32\cmd.exe
%HOMEDRIVE% C:
%HOMEPATH%  C:\Users\Username
%LOCALAPPDATA%  C:\Users\Username\AppData\Local
%PROGRAMDATA%   C:\ProgramData
%PROGRAMFILES%  C:\Program Files
%PROGRAMFILES(X86)% C:\Program Files (x86) (only in 64-bit version)
%PUBLIC%    C:\Users\Public
%SystemDrive%   C:
%SystemRoot%    C:\Windows
%TEMP% and %TMP%    C:\Users\Username\AppData\Local\Temp
%USERPROFILE%   C:\Users\Username
%WINDIR%    C:\Windows
26
votes

You can also use

Environment.ExpandEnvironmentVariables("%AppData%\\DateLinks.xml");

to expand the %AppData% variable.

15
votes

In .net2.0 you can use the variable Application.UserAppDataPath

7
votes

I don't think putting %AppData% in a string like that will work.

try

Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData).ToString()
6
votes

AppData ⇝ Local aka (C:\Users\<user>\AppData\Local):

Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)

AppData ⇝ Roaming aka (C:\Users\<user>\AppData\Roaming):

Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)

Additionally, it could be handy to know:

  • Environment.SpecialFolder.ProgramFiles - for Program files X64 folder
  • Environment.SpecialFolder.ProgramFilesX86 - for Program files X86 folder

For the full list check here.

3
votes

Just wanted to share another way of accessing 'App_Data' folder in my mvc application in case that someone needs this.

 Path.Combine(HttpRuntime.AppDomainAppPath,"App_Data")
1
votes

This is working for me in a console application - 

string appData = System.Environment.GetEnvironmentVariable("APPDATA");
1
votes

For ASP.NET, the Load User Profile setting needs to be set on the app pool but that's not enough. There is a hidden setting named setProfileEnvironment in \Windows\System32\inetsrv\Config\applicationHost.config, which for some reason is turned off by default, instead of on as described in the documentation. You can either change the default or set it on your app pool. All the methods on the Environment class will then return proper values.