Question

So say I have a button (MyButton) that binds to:

public ICommand MyCommand { get; set; }

I register this command with:

MyCommand = new DelegateCommand<object>(DoSomething);

Now if I do

MyButton.IsEnabled = false;

It doesn’t do anything, i.e., the button is still enabled. I know that the command is causing this to happen because if I remove the new delegatecommand code above then the button appears disabled.

My questions are:
1. Is there a way for me to tell this binding to a command not to mess with my button’s IsEnabled
2. Is there a way to change the visibility via only the commanding property (which would probably be the more correct way anyway)

Thanks!!

Answer 1

You need to add logic into your command for the CanExecute delegate, e.g.:

ICommand comand = new DelegateCommand<object>
    (
    executeMethod: delegate { DoSomething(); }
    ,
    canExecuteMethod: delegate { return _buttonEnabled; }
    );

_buttonEnabled = false;

CommandManager.InvalidateRequerySuggested();

_buttonEnabled = true;

CommandManager.InvalidateRequerySuggested();

The “_buttonEnabled” variable should really represent the state of your application that controls whether the button should actually be enabled or disabled. For example, it could be “_isSomethingDone” and be true\false depending on the state of your application. This would then disable your button whilst “DoSomething” is actually doing something.

Rough example:

ICommand saveCommand = new DelegateCommand<object>
    (
    executeMethod: delegate { Save(); }
    ,
    canExecuteMethod: delegate { return _canSave; }
    );

private void Save()
{
    _canSave = false;

    CommandManager.InvalidateRequerySuggested();

    //do save...

    _canSave = true;

    CommandManager.InvalidateRequerySuggested();
}