如何根据属性隐藏wpf datagrid列 [英] How to hide wpf datagrid columns depending on a property

问题描述

我有以下WPF示例程序：

I have the following WPF sample program:

Xaml：

<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>

代码背后：

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;            
    }
}

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; }
}

如您所见，我想隐藏第二个datagrid列，如果标志属性设置为false。但它不行。我在Visual Studio输出窗口中收到以下绑定错误：

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：找不到与
引用'RelativeSource FindAncestor，
AncestorType ='System.Windows.Window'，AncestorLevel ='1''。
BindingExpression：Path = DataContext.Flag; DataItem = null;目标元素
是'DataGridTextColumn'（HashCode = 44856655）;目标属性是
'可见性'（类型'Visibility'）

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')

我的代码中有关可见性属性？

推荐答案

datagrid中的一列是不抽象的对象出现在视觉树中，因此您不能使用 RelativeSource -binding， ElementName 将无法正常工作，因为它不会找到一个管理FrameworkContentElement，所以你是一个绑定。

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.

一种工作方式是通过源和 x：参考 ，为此，您将需要命名您的窗口并将列移动到其资源以避免循环依赖错误：

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"/>
                <!-- ... -->

非常有趣。

这篇关于如何根据属性隐藏wpf datagrid列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！