public ClientViewModel(IDataAccessService dataAccessService, ViewModelLocator viewModelLocator)
{
_dataAccessService = dataAccessService;
_viewModelLocator = viewModelLocator;
//_clients = new ObservableCollection<Client>();
//GetClients();
_clients = _dataAccessService.GetClients();
OpenExistedClientTabCommand = new RelayCommand<Client>(OpenExistedClientTab);
// Register the Tab Close Messenger
Messenger.Default.Register<Client>(this, "CloseClientTabItem", CloseClientTab);
}