WPF IsEnabled网格

Question

当我的属性为null时，我想禁用网格，当不是Null时，启用网格。

在我的.XAML：

  <Grid Grid.Row="2" IsEnabled="{Binding ElementName=dgCustomers, Path=SelectedItem}">
      <my:ProductsHistoryDetailView />
  </Grid>

在我的ViewModel.cs：

    public ProductHistory SelectedItem
    {
        get { return _SelectedItem; }
        set
        {
            if (_SelectedItem != value)
            {
                _SelectedItem = value;
                RaisePropertyChanged(() => SelectedItem);
            }
        }
    }

Answer 1

使用样式触发器更改已启用的属性，而不是尝试直接绑定属性。

<Grid Grid.Row="2">
    <Grid.Style>
        <Style TargetType="Grid">
           <Setter Property="IsEnabled" Value="True"/>
           <Style.Triggers>
               <DataTrigger Binding="{Binding ElementName=dgCustomers, Path=SelectedItem"}" Value={x:Null}>
                    <Setter Property="IsEnabled" Value="False"/>
               </DataTrigger>
           </Style.Triggers>            
        </Style>
    </Grid.Style>
</Grid>

Answer 2

你可以用IValueConverter

<Grid Grid.Row="2" IsEnabled="{Binding 
    ElementName=dgCustomers, Path=SelectedItem, 
    Converter={StaticResource NullToFalseConverter}">

public class NullToFalseConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value == null ? false : true;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

或者，可以更容易地将另一个属性IsSelected添加到视图模型中，您可以直接绑定到IsEnabled。

public bool IsSelected
{
    get { return _isSelected; }
    set
    {
        if (_isSelected != value)
        {
            _isSelected = value;
            RaisePropertyChanged(() => IsSelected);
        }
    }
}

public ProductHistory SelectedItem
{
    get { return _SelectedItem; }
    set
    {
        if (_SelectedItem != value)
        {
            _SelectedItem = value;
            RaisePropertyChanged(() => SelectedItem);
        }
        IsSelected = value != null;
    }
}

Answer 3

请确保选择项具有如下所示的有效值：

<Grid Grid.Row="2" IsEnabled="{Binding ElementName=dgCustomers, Path=SelectedItem.Value}">
      <my:ProductsHistoryDetailView />
  </Grid>