将按钮的属性绑定到静态字段类（MVVM）

Question

i have buttons on my mainwindow and i want to enable and disable that control by a static field class. is this possible without going to the code behind?

mainwindow

<Button x:Name="btnAanpassen" Content="Aanpassen" Grid.Row="1" Command="{Binding SaveItemCommand}" CommandParameter="{Binding SelectedItem}" IsEnabled="{Binding EnableDisable}"/>

my vm

    private static object _selectedItem;
    public static object SelectedItem
    {
        get { return _selectedItem; }
        set {
            if (SelectedItem != null)
            {
                //enable control
            }
            else
            {
                //disable control
            }
            _selectedItem = value; }
    }

    private Boolean _enableDisable;
    public Boolean EnableDisable
    {
        get { return _enableDisable; }
        set { _enableDisable = value; OnPropertyChanged("EnableDisable"); }
    }

Answer 1

You can try this:

<Window.Resources>
    <yourNS:YourMVVM x:Key="mvvm"/>
</Window.Resources>

...

<Button x:Name="btnAanpassen" Content="Aanpassen" Grid.Row="1" Command="{Binding SaveItemCommand}" 
        CommandParameter="{Binding Source={StaticResource mvvm}, Path=SelectedItem}" IsEnabled="{Binding EnableDisable}"/>

Answer 2

There is some issue on using Static Property in this case. I have a workaround on this problem. See below snippets suits for you.

public partial class MainWindow : Window,INotifyPropertyChanged 
{
    public event PropertyChangedEventHandler PropertyChanged;
    public static object mySharedVariableToOtherClass = value;
    private object _selectedItem;

    public object SelectedItem
    {
        get { return _selectedItem; }
        set
        {
            _selectedItem = value;
            mySharedVariableToOtherClass = null;
            OnPropertyChanged("SelectedItem");
        }
    }

    public MainWindow()
    {
        InitializeComponent();
        this.DataContext = this;
        SelectedItem = "vimal";
    }
    private void Button_Click(object sender, RoutedEventArgs e)
    {
        SelectedItem = null;
    }
    public void OnPropertyChanged(string PropertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(PropertyName));    
        }
    }
}

In above snippet I have declared SelectedItem property as a normal Property which is used to bind to UIElement . I have also declared a Property called mySharedVariableToOtherClass which is Static and used to set the value inside from the SelectedItem property. This is Static , so you can access it from other classes too. In my openion Trigger is the right choice here to disable the Button control.

<Grid Name="MainGrid">
    <Button Width="100"
            Height="40"
            Click="Button_Click">
        <Button.Style>
            <Style>
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Path=SelectedItem}"
                                 Value="{x:Null}">
                        <Setter Property="Button.IsEnabled"
                                Value="False" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </Button.Style>
    </Button>
    <TextBlock Width="200"
               Height="30"
               Text="{Binding SelectedItem, UpdateSourceTrigger=PropertyChanged,Mode=TwoWay}"
               Margin="74,46,69,154" />

</Grid>

Answer 3

Try the way mentioned in the following link

WPF TwoWay binding to a static property

Answer 4

You can't bind directly to a static property. If you really need this property to be static, one approach is to create a proxy property that gets and sets it. It's based on the singleton pattern .

private static readonly ClassName _this = new ClassName();

public object ProxySelectedItem
{
    get { return SelectedItem; }
    set { SelectedItem = value; }
}

private static object _selectedItem;
public static object SelectedItem
{
    get { return _selectedItem; }
    set
    {
        if (SelectedItem != null)
        {
            _this.EnableDisable = true;
        }
        else
        {
            _this.EnableDisable = false;
        }
        _selectedItem = value;
        _this.OnPropertyChanged("ProxySelectedItem");
    }
}

private bool _enableDisable;
public bool EnableDisable
{
    get { return _enableDisable; }
    set 
    {
        _enableDisable = value;
        OnPropertyChanged("EnableDisable"); 
    }
}