I have application that works with Model View ViewModel.
In my model I have a List based on my Client class.

```
public class Client
{
    public string Name { get; set; }

    public string Ip { get; set; }

    public string Mac { get; set; }
}

```

In my ClientRepository I make a List from XML file with my Client class.

```
    public ClientRepository()
    {
        var xml = "Clients.xml";
        if (File.Exists(xml))
        {
            _clients = new List<Client>();
            XDocument document = XDocument.Load(xml);
            foreach (XElement client in document.Root.Nodes())
            {
                string Name = client.Attribute("Name").Value;
                string Ip = client.Element("IP").Value;
                string Mac = client.Element("MAC").Value;
                _clients.Add(new Client() { Mac = Mac, Name = Name, Ip = Ip });
            }
        }
    }

```

In my UI/UX I have 3 Textboxes 1 for MAC, 1 IP and 1 Name I also have a Button thats has a binding to AddClientCommand.

```
<Label Grid.Row="0" Grid.Column="0" Content="Host Name:"/>
<TextBox Grid.Row="0" Grid.Column="1" x:Name="tbHostName" Height="20" Text="{Binding Path=newClient.Name, UpdateSourceTrigger=PropertyChanged}"/>
<Label Grid.Row="1" Grid.Column="0" Content="IP Address:"/>
<TextBox Grid.Row="1" Grid.Column="1" x:Name="tbIP" Height="20" Text="{Binding Path=newClient.Ip, UpdateSourceTrigger=PropertyChanged}"/>
<Label Grid.Row="2" Grid.Column="0" Content="MAC Address"/>
<TextBox Grid.Row="2" Grid.Column="1" x:Name="tbMAC" Height="20" Text="{Binding Path=newClient.Mac, UpdateSourceTrigger=PropertyChanged}"/>
<Button Grid.Row="3" Grid.Column="0" Content="Remove" x:Name="bRemove" Margin="3 0 3 0" Click="bRemove_Click"/>
<Button Grid.Row="3" Grid.Column="1" Content="Add" x:Name="bAdd" Margin="3 0 3 0" Click="bAdd_Click" Command="{Binding AddClientCommand}"/>

```

To come to my point: **What I want to know is what is the best way to implement the AddClientCommand?**

What I currently have and I know it doesn't work:

```
    public ClientViewModel()
    {
        _repository = new ClientRepository();
        _clients = _repository.GetClients();

        WireCommands();
    }

    private void WireCommands()
    {
        AddClientCommand = new RelayCommand(AddClient);
    }

    public Client newClient
    {
        get
        {
            return _newClient;
        }
        set
        {
            _newClient = value;
            OnPropertyChanged("newClient");
            AddClientCommand.isEnabled = true;
        }
    }

    public void AddClient()
    {
        _repository.AddClient(newClient);
    }

```

RelayCommand class:

```
public class RelayCommand : ICommand
{
    private readonly Action _handler;
    private bool _isEnabled;

    public RelayCommand(Action handler)
    {
        _handler = handler;
    }

    public bool isEnabled
    {
        get { return true; }
        set
        {
            if (value != isEnabled)
            {
                _isEnabled = value;
                if (CanExecuteChanged != null)
                {
                    CanExecuteChanged(this, EventArgs.Empty);
                }
            }
        }
    }

    public bool CanExecute(object parameter)
    {
        return isEnabled;
    }

    public event EventHandler CanExecuteChanged;

    public void Execute(object parameter)
    {
        _handler();
    }
}

```