Folder Tree WPF Control: Part 1 - View Model

Drive.cs

namespace GeekJ.FolderTreeControl.Model
{
    public class Drive : FolderTreeItem
    {
        private DriveInfo _driveInfo;
        public DriveInfo DriveInfo
        {
            get
            {
                return _driveInfo;
            }
            set
            {
                _driveInfo = value;
            }
        }

        public Drive(DriveInfo driveInfo)
        {
            DriveInfo = driveInfo;
        }

        public string Label
        {
            get
            {
                return DriveInfo.Name;
            }
        }

        private ObservableCollection<Folder> _folders;
        public ObservableCollection<Folder> Folders
        {
            get
            {
                if (_folders == null)
                {
                    _folders = new ObservableCollection<Folder>();
                    _folders.Add(new Folder());
                }
                return _folders;
            }
        }

        public override void LoadChildren()
        {
            Folders.Clear();
            foreach (var child in Folder.LoadSubFolders(DriveInfo.RootDirectory))
            {
                Folders.Add(child);
            }
        }
    }
}

Folder.cs

namespace GeekJ.FolderTreeControl.Model
{
    public class Folder : FolderTreeItem
    {
        private System.IO.DirectoryInfo directoryInfo;

        public Folder()
        {

        }

        public Folder(System.IO.DirectoryInfo directoryInfo)
        {
            this.directoryInfo = directoryInfo;
        }

        private ObservableCollection<Folder> _folders;
        public ObservableCollection<Folder> Folders
        {
            get
            {
                if (_folders == null)
                {
                    _folders = new ObservableCollection<Folder>();
                    _folders.Add(new Folder());
                }
                return _folders;
            }
        }

        public string Label
        {
            get
            {
                return directoryInfo.Name;
            }
        }

        public override void LoadChildren()
        {
            Folders.Clear();
            foreach (var child in Folder.LoadSubFolders(directoryInfo))
            {
                Folders.Add(child);
            }
        }

        internal static IEnumerable<Folder> LoadSubFolders(System.IO.DirectoryInfo directoryInfo)
        {
            return directoryInfo.EnumerateDirectories().Select(x => new Folder(x));            
        }
    }
}

FolderTreeViewModel.cs

namespace GeekJ.FolderTreeControl.Model
{
    public class FolderTreeViewModel : ViewModelBase
    {
        private ObservableCollection<Drive> _drives;
        public ObservableCollection<Drive> Drives
        {
            get { return _drives; }
            set
            {
                _drives = value;
                OnPropertyChanged("Drives");
            }
        }

        public FolderTreeViewModel()
        {
            _drives = new ObservableCollection<Drive>();
            foreach (var driveInfo in DriveInfo.GetDrives())
            {
                _drives.Add(new Drive(driveInfo));
            }
        }
    }
}