WPF - How to force a Command to re-evaluate 'CanExecute' via its CommandBindings

Not the prettiest in the book, but you can use the CommandManager to invalidate all commandbinding:

CommandManager.InvalidateRequerySuggested();

See more info on MSDN

For anyone who comes across this later; If you happen to be using MVVM and Prism, then Prism's DelegateCommand implementation of ICommand provides a .RaiseCanExecuteChanged() method to do this.

I couldnt use CommandManager.InvalidateRequerySuggested(); because I was getting performance hit.

I have used MVVM Helper's Delegating command, which looks like below (i have tweaked it a bit for our req). you have to call command.RaiseCanExecuteChanged() from VM

public event EventHandler CanExecuteChanged{    add    {        _internalCanExecuteChanged += value;        CommandManager.RequerySuggested += value;    }    remove    {        _internalCanExecuteChanged -= value;        CommandManager.RequerySuggested -= value;    }}/// <summary>/// This method can be used to raise the CanExecuteChanged handler./// This will force WPF to re-query the status of this command directly./// </summary>public void RaiseCanExecuteChanged(){    if (canExecute != null)        OnCanExecuteChanged();}/// <summary>/// This method is used to walk the delegate chain and well WPF that/// our command execution status has changed./// </summary>protected virtual void OnCanExecuteChanged(){    EventHandler eCanExecuteChanged = _internalCanExecuteChanged;    if (eCanExecuteChanged != null)        eCanExecuteChanged(this, EventArgs.Empty);}