Question

I’m having an issue with passing a parameter to a relaycommand using the GalaSoft MVVM Light framework. I know that mvvm light’s implementation of relaycommand doesn’t use lambda parameters, so I did some research and found a way that people worked around it by doing something like this:

public RelayCommand ProjMenuItem_Edit
{
    get
    {
        if (_projmenuItem_Edit == null)
        {
            //This should work....
            _projmenuItem_Edit = new RelayCommand(ProjEditNode);
        }
        return _projmenuItem_Edit;
    }
}

private void ProjEditNode(object newText)
{
    var str = newText as string;
    OrganLocationViewModel sel = 
        ProjectOrganLocationView.GetExtendedTreeView().GetTopNode();

    //Console.WriteLine(sel.OrganDisplayName);
    sel.OrganDisplayName = str;
}

However, I keep getting an error on the line _projmenuItem_Edit = new RelayCommand(ProjEditNode); that says Argument 1: cannot convert from 'method group' to 'System.Action'

What am I missing?

Answer 1

I believe this will work:

_projmenuItem_Edit = new RelayCommand<object>((txt)=>ProjEditNode(txt));

— EDIT —

You’ll need to define your RelayCommand with the type as well:

e.g.

public RelayCommand<string> myCommand { get; private set; }
myCommand = new RelayCommand<string>((s) => Test(s));

private void Test(string s)
{
    throw new NotImplementedException();
}