How does one “disable” a button in WPF using the MVVM pattern?

Question

I\'m trying to get a grasp on WPF and MVVM and have been making good progress. The WPF and MVVM side of things are going well.

However, the XAML and data binding sid

Answer 1

This works too:

View:

        <Button>
            <Button.Style>
                <Style>
                    <Setter Property="Content" Value="Scream" />
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding btnEnabled}" Value="True">
                            <Setter Property="IsEnabled" Value="True" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </Button.Style>
        </Button>

ViewModel:

    private bool _btnEnabled;
    public bool btnEnabled
    {
        get { return _btnEnabled; }
        set
        {
            if (_btnEnabled != value)
            {
                _btnEnabled = value;
                OnPropertyChanged();
            }
        }
    }

Answer 2

If you return CanExecute of ICommand a value of false, then Button will be disabled. So whatever command your button is bound to, see if you can return CanExecute a value of false when you want to disable it.

Answer 3

Change in ViewModel file:

public bool IsButtonEnabled { get { return _isButtonEnabled; }

set
{
    if (_isButtonEnabled == value)
    {
        return;
    }

    _isButtonEnabled = value;
    OnPropertyChanged("IsButtonEnabled");
}
}

public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

Changes in the XAML file for Button: IsEnabled="{Binding IsButtonEnabled}"

Answer 4

Just bind the IsEnabled property of the Button to CanClose:

<Button IsEnabled="{Binding CanClose}"/>

Answer 5

By way of using the command pattern. In your view model:

public class MyViewModel : ViewModel
{
    private readonly ICommand someCommand;

    public MyViewModel()
    {
        this.someCommand = new DelegateCommand(this.DoSomething, this.CanDoSomething);
    }

    public ICommand SomeCommand
    {
        get { return this.someCommand; }
    }

    private void DoSomething(object state)
    {
        // do something here
    }

    private bool CanDoSomething(object state)
    {
        // return true/false here is enabled/disable button
    }
}

In your XAML:

<Button Command="{Binding SomeCommand}">Do Something</Button>

Read this post to find out more about the DelegateCommand.