RelayCommand from lambda with constructor parameters

Question

If, in a XAML file, I bind a Button to \"Command\" from the following class, then clicking the Button does not cause DoIt to be executed:

class Thing()
{
  p         


        

Answer 1

your Problem is that calling the Method DoIt is inside another anonymous Method created by the lamda expression. Your expression

() => DoIt(p1);

creates a anonymous Method without parameters (seen as there are no variables provided in the first braces).

I would recommend you to use the generic constructor from mvvm-light for creating the Command:

class Thing
{
    public Thing()
    {
       Command = new GalaSoft.MvvmLight.Command.RelayCommand(DoIt);
    }

    private void DoIt(bool p)
    {
       p.DoSomething(p);
    }

    public System.Windows.Input.ICommand Command { get; private set; }
}

Then just bind the Button to the "Command".