如何在运行时(安装时)从wix源代码中获取MSI文件所在的路径

<CustomAction Id="GetMSIPath" BinaryKey="CustomActionBinary" DllEntry="GetMSIPath" Execute="immediate" Return="check" />

<Binary Id="CustomActionBinary" SourceFile="CustomAction.dll" />

<InstallExecuteSequence>
  <Custom Action="GetMSIPath" Before="InstallInitialize" />
</InstallExecuteSequence>

using System;
using Microsoft.Deployment.WindowsInstaller;

namespace CustomAction
{
    public class CustomActions
    {
        [CustomAction]
        public static ActionResult GetMSIPath(Session session)
        {
            string msiPath = session["OriginalDatabase"];
            session["MSIPath"] = msiPath;
            return ActionResult.Success;
        }
    }
}

<Property Id="MSIPath" />

<CustomActionRef Id="GetMSIPath" />

<Component Directory="INSTALLFOLDER" Guid="PUT-GUID-HERE">
  <File Source="$(var.MyApp.TargetPath)" />
  <RegistryValue Root="HKCU" Key="Software\MyApp" Name="Installed" Type="integer" Value="1" KeyPath="yes" />
  <Shortcut Id="startmenuMyApp" Directory="ProgramMenuFolder" Name="MyApp" WorkingDirectory="INSTALLFOLDER" Icon="MyApp.exe" IconIndex="0" Advertise="yes" />
  <RemoveFolder Id="INSTALLFOLDER" On="uninstall" />
  <RemoveRegistryKey Root="HKCU" Key="Software\MyApp" Action="removeOnUninstall" />
  <Condition><![CDATA[MSIPath <> ""]]></Condition>
</Component>