如何隐藏取决于物业WPF DataGrid列 [英] How to hide wpf datagrid columns depending on a property

问题描述

我有以下的WPF示例程序：

I have the following WPF sample program:

XAML中：

<Window x:Class="AncestorArie.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <BooleanToVisibilityConverter x:Key="BoolToVis" />
    </Window.Resources>
    <Grid>
        <DataGrid AutoGenerateColumns="False" Name="Blumen" 
                  ItemsSource="{Binding Leaves}">
            <DataGrid.Columns>
                <DataGridTextColumn Binding="{Binding Color}" 
                                    Header="Farbe" Width="160" />
                <DataGridTextColumn Binding="{Binding Size}" 
                                    Header="Größe" Width="60"
                    Visibility="{Binding Path=DataContext.Flag, 
                                RelativeSource={RelativeSource Findancestor, 
                                AncestorType={x:Type Window}}, 
                                Converter={StaticResource BoolToVis}}" />
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

背后code：

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        Flowers rose = new Flowers();
        rose.Leaves = new ObservableCollection<Leaf>();

        rose.Flag = false;

        Leaf L1 = new Leaf();
        L1.Color = "rot";
        L1.Size = 3;
        rose.Leaves.Add(L1);

        Leaf L2 = new Leaf();
        L2.Color = "gelb";
        L2.Size = 2;
        rose.Leaves.Add(L2);

        this.DataContext = rose;            
    }
}

和模型类是：

public class Leaf
{
    public string Color { get; set; }
    public int Size { get; set; }
}

public class Flowers
{
    public bool Flag { get; set; }
    public ObservableCollection<Leaf> Leaves { get; set; }
}

正如你所看到的，我要隐藏的第二个DataGrid列，如果标志属性设置为false。但是，这是行不通的。我得到以下绑定错误在Visual Studio Output窗口：

As you can see, I want to hide the 2nd datagrid column, if the Flag property is set to false. But it doesn't work. I get the following binding error in the Visual Studio Output window:

System.Windows.Data错误：4：无法与绑定找到源
  参考的RelativeSource FindAncestor，
  AncestorType ='System.Windows.Window'，AncestorLevel ='1''。
  BindingEx pression：路径= DataContext.Flag;的DataItem = NULL;目标元素
  是DataGridTextColumn（哈希code = 44856655）; target属性
  '能见度'（类型'能见度'）

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Window', AncestorLevel='1''. BindingExpression:Path=DataContext.Flag; DataItem=null; target element is 'DataGridTextColumn' (HashCode=44856655); target property is 'Visibility' (type 'Visibility')

这有什么不对有关可见我的code 属性？

What is wrong in my code concerning the Visibility attribute?

推荐答案

在DataGrid中的一列是不显示在可视化树的抽象对象，所以你不能用的RelativeSource 结合位，的ElementName 将无法工作要么因为它不会找到一个管理FrameworkContentElement上，所以你是实物绑定的。

A column in a datagrid is an abstract object which does not appear in the visual tree, thus you cannot use RelativeSource-binding, ElementName will not work either since it will not find a governing FrameworkContentElement so you are in kind of a bind.

这是工作的一种方式是通过来源和 X：参考 ，为您将需要命名窗口和列移动到它的资源，以避免周期性的依赖错误：

One way that works is via Source and x:Reference, for that you will need to name your window and move the column to its resources to avoid a cyclical dependency error:

<Window Name="_window" ...>
    <Window.Resources>
        <DataGridTextColumn x:Key="ThatPeskyColumn"
                            Binding="{Binding Size}"
                            Visibility="{Binding DataContext.Flag, Source={x:Reference _window}, Converter={StaticResource BoolToVis}}"/>
    </Window.Resources>
    <!-- ... -->
        <DataGrid AutoGenerateColumns="False" Name="Blumen" 
                  ItemsSource="{Binding Leaves}">
            <DataGrid.Columns>
                <StaticResource ResourceKey="ThatPeskyColumn"/>
                <!-- ... -->

大乐趣。

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