Question

MultiBinding转换器的问题
我知道两次发送相同的值是没有意义的我这样做是为了隔离那个单一的约束力在转换器中，我得到了一个关于强制转换为bool的错误值是

{DependencyProperty.UnsetValue}

但“RWnet”是一个bool

<ContentPresenter Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2"
        x:Name="fieldTemplateDetail"
        Content="{Binding}"
        ContentTemplateSelector="{StaticResource fieldTemplateSelector}">
    <ContentPresenter.Visibility>
        <MultiBinding Converter="{StaticResource visabilityConverterTwoBool}">
            <Binding Path="RWnet" />
            <Binding Path="RWnet" />
        </MultiBinding>
    </ContentPresenter.Visibility>
</ContentPresenter>

public class VisabilityConverterTwoBool : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        if (values == null) return Visibility.Visible;
        if (values.Length != 2) return Visibility.Visible;
        try
        {
            if ((bool)values[0] == false) return Visibility.Collapsed;
            if ((bool)values[1] == false) return Visibility.Collapsed;
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex.Message, "VisabilityConverterTwoBool");
            Debug.WriteLine(values[0].ToString());
            Debug.WriteLine(values[1].ToString());
        }
        return Visibility.Visible;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        return null;
    }
}

如果我发送实际多重绑定的另一半，它可以工作（错误的结果，但没有错误）

<Binding ElementName="cbEditMode" Path="IsChecked" />

但是这很好用 RWnet是一个bool

<ContentPresenter Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2"
        Visibility="{Binding Path=RWnet, Converter={StaticResource bvc}}"
        x:Name="fieldTemplateDetail"
        Content="{Binding}"
        ContentTemplateSelector="{StaticResource fieldTemplateSelector}"/>

<BooleanToVisibilityConverter x:Key="bvc" />

对于McGarnagle来说这是数据上下文

<ListBox  Grid.Row="4" Grid.Column="0" Grid.ColumnSpan="2" x:Name="lbCurDocFields" 
            ItemsSource="{Binding Source={StaticResource curDocFields}}" LostFocus="lbCurDocFields_LostFocus"

Answer 1

根据您对数据上下文的连接方式，无法保证在您预期的情况下准备好绑定。完全验证输入，它应该解决问题：

if (values.Length != 2 && values[0] as bool? == null || values[1] as bool? == null)
    return Visibility.Visible;

MultiBinding转换器绑定

1 个答案: