C#: Disable button during search/calculation

Question

I have a search dialog where I want to disable the search button during the search. This is the current code but the button does not get deactivated

View:

<Button Content="Search" 
        Command="{Binding StartSearchCommand}" 
        IsEnabled="{Binding IsNotSearching}" />

ViewModel:

private bool _isNotSearching;
public bool IsNotSearching
{
    get { return _isNotSearching; }
    set
    {
        _isNotSearching = value;
        OnPropertyChanged("IsNotSearching");
    }
}


private RelayCommand<object> _startSearchCommand;
public ICommand StartSearchCommand
{
    get
    {
        if (_startSearchCommand == null)
            _startSearchCommand = new RelayCommand<object>(p => ExecuteSearch());
        return _startSearchCommand;
    }
}
private void ExecuteSearch()
{
    IsNotSearching = false;
    //do some searching here
    IsNotSearching = true;
}

Answer 1

I've made an AsyncDelegateCommand for that reason (based on famous DelegateCommand), it internally disable command (in UI) during executing command action:

public class AsyncDelegateCommand : ICommand
{
    readonly Action<object> _execute;
    readonly Predicate<object> _canExecute;
    bool _running;

    public event EventHandler CanExecuteChanged;

    public AsyncDelegateCommand(Action<object> execute, Predicate<object> canExecute = null)
    {
        _execute = execute;
        _canExecute = canExecute;
    }

    public bool CanExecute(object parameter)
    {
        return (_canExecute == null ? true : _canExecute(parameter)) && !_running;
    }

    public async void Execute(object parameter)
    {
        _running = true;
        Update();
        await Task.Run(() => _execute(parameter));
        _running = false;
        Update();
    }

    public void Update()
    {
        if (CanExecuteChanged != null)
            CanExecuteChanged(this, EventArgs.Empty);
    }
}

xaml:

<Button Command="{Binding SomeCommand}" .../>

ViewModel:

AsyncDelegateCommand SomeCommand { get; }

    // in constructor
    SomeCommand = new AsyncDelegateCommand(o =>  { Thread.Sleep(5000); }); // code to run