title: Using WixSharp how to get the proper InstallDir path during a Custom Action which is executed at uninstall
body: <p>I created a msi Setup with WiX using WixSharp. It includes several Custom Actions.
  For instance during installation time I am executing some batch files which are installing and starting a service. And during uninstall it should stop and uninstall the service again. </p>
  
  <pre><code>var dir = new InstallDir(@"%ProgramFiles%\MyCompany\MyProduct",
                               new Files(@"..\..\..\AllMyFiles\*.*"));
  
  var project = new Project("MyProduct", dir) {
       GUID = new Guid("7f22db65-2b23-4df2-b2b2-495f2d369c3d"),
       Version = new Version(1, 0, 0, 0),
       UI = WUI.WixUI_InstallDir,
       Platform = Platform.x64
  };
  
  project.Actions = new WixSharp.Action[] {
       new ElevatedManagedAction(CustomActions.InstallService,Return.check, When.Before, Step.InstallFinalize, Condition.NOT_Installed),
       new ElevatedManagedAction(CustomActions.StartService,Return.check, When.After, Step.PreviousAction, Condition.NOT_Installed),
       new ElevatedManagedAction(CustomActions.StopService,Return.check, When.Before, Step.RemoveFiles, Condition.Installed),
       new ElevatedManagedAction(CustomActions.UninstallService,Return.check, When.After, Step.PreviousAction, Condition.Installed)
  };
  </code></pre>
  
  <p>Now here comes the crucial part. I need to execute a batch file during install and uninstall which is located somewhere in INSTALLDIR:</p>
  
  <pre><code>[CustomAction]
  public static ActionResult StartService(Session session) {
  
       string installDir = session.Property("INSTALLDIR"); //&lt;--this works on install even when using a custom path
       string workingDir = Path.Combine(installDir, @"\SomePathToTheBatchFile");
       RunCmdMethode(workingDir, "something.bat -some arguments");
  
       return ActionResult.Success;
  }
  [CustomAction]
  public static ActionResult UninstallService(Session session) {
  
       string installDir = session.Property("INSTALLDIR"); //&lt;--this does not give back the right path on uninstall in case the default path was changed during installation
       string workingDir = Path.Combine(installDir, @"\SomePathToTheBatchFile");
       RunCmdMethode(workingDir, "something.bat -some arguments");
  
       return ActionResult.Success;
  }
  </code></pre>
  
  <p>Everything runs smoothly when using the default path for installation. But if I change the default install path during installation to some custom path the installation step properly finds the .bat and executes it but during uninstall it searches for the .bat file in the default folder. Although the Uninstaller properly removes the files on the correct location. So the custom install path must be saved somewhere. How do I access it properly? </p>