问为什么jQuery FileTree未设置为显示文件？

EN

[HttpPost]
//notice the added additional params to the expected request variables
//these appear to match the names of the jQuery options
public virtual ActionResult GetFiles(string dir, bool multiSelect, 
    bool onlyFolders, bool onlyFiles)
{
    const string baseDir = @"/App_Data/userfiles/";

    dir = Server.UrlDecode(dir);
    string realDir = Server.MapPath(baseDir + dir);

    //validate to not go above basedir
    if (! realDir.StartsWith(Server.MapPath(baseDir)))
    {
        realDir = Server.MapPath(baseDir);
        dir = "/";
    }

    List<FileTreeViewModel> files = new List<FileTreeViewModel>();

    DirectoryInfo di = new DirectoryInfo(realDir);

    foreach (DirectoryInfo dc in di.GetDirectories())
    {                
        files.Add(new FileTreeViewModel() { Name = dc.Name, Path = String.Format("{0}{1}\\", dir, dc.Name), IsDirectory = true });
    }

    foreach (FileInfo fi in di.GetFiles())
    {
        files.Add(new FileTreeViewModel() { Name = fi.Name, Ext = fi.Extension.Substring(1).ToLower(), Path = dir+fi.Name, IsDirectory = false });
    }
    //lets filter some results using the properties of 
    //the `FileTreeViewModel()` class
    //I have no idea how you are wanting to use multiSelect, so 
    //it has been left out of this example.
    if(onlyFolders){
        files = files.Where(x=>x.IsDirectory).ToList();
    }
    if(onlyFiles){
        files = files.Where(x=>!x.IsDirectory).ToList();
    }
    return PartialView(files);
}