WPF 中 DataGridColumn 的绑定可见性 [英] Binding Visibility for DataGridColumn in WPF

问题描述

如何通过绑定隐藏 WPF DataGrid 中的列?

How can I hide a column in a WPF DataGrid through a Binding?

这就是我所做的:

<DataGridTextColumn Header="Column header"
                    Binding="{Binding ColumnValue}"
                    Width="100"
                    ElementStyle="{StaticResource DataGridRightAlign}"
                    Visibility="{Binding MyColumnVisibility}" />

这就是我得到的(除了列仍然可见):

And this is what I got (besides the column still visible):

System.Windows.Data 错误:2:找不到目标元素的管理 FrameworkElement 或 FrameworkContentElement.BindingExpression:Path=MyColumnVisibility;数据项=空；目标元素是DataGridTextColumn"(HashCode=1460142)；目标属性是可见性"(类型可见性")

System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=MyColumnVisibility; DataItem=null; target element is 'DataGridTextColumn' (HashCode=1460142); target property is 'Visibility' (type 'Visibility')

如何修复绑定?

推荐答案

首先，DataGridTextColumn(或任何其他支持的 dataGrid 列)不位于 <代码>数据网格.因此，默认情况下它不继承DataGrid 的DataContext.但是，它仅适用于 Binding DP，不适用于 DataGridColumn 上的其他 DP.

First of all, DataGridTextColumn (or any other supported dataGrid column) does not lie in the Visual tree of the DataGrid. Hence, by default it doesn't inherit the DataContext of the DataGrid. However, it works for Binding DP only and for no other DP's on DataGridColumn.

由于它们不在同一个 VisualTree 中，任何使用 RelativeSource 获取 DataContext 的尝试都不会奏效，因为 DataGridTextColumn 无法遍历到 DataGrid.

Since they don't lie in the same VisualTree, any attempt to get the DataContext using RelativeSource won't work as well because DataGridTextColumn is unable to traverse up to the DataGrid.

不过，还有另外两种方法可以实现这一点:

There are two other ways to achieve this though:

首先使用 Freezable 类.Freezable 对象可以继承 DataContext，即使它们不在可视化或逻辑树中——我们可以利用这一点.

First using a Freezable class. Freezable objects can inherit the DataContext even when they’re not in the visual or logical tree –We can take advantage of that.

首先，创建一个继承自 Freezable 和 Data DP 的类，我们可以使用它在 XAML 中进行绑定:

First, create a class inheriting from Freezable and Data DP which we can use to bind in XAML:

public class BindingProxy : Freezable
{
    #region Overrides of Freezable

    protected override Freezable CreateInstanceCore()
    {
        return new BindingProxy();
    }

    #endregion

    public object Data
    {
        get { return (object)GetValue(DataProperty); }
        set { SetValue(DataProperty, value); }
    }

    public static readonly DependencyProperty DataProperty =
        DependencyProperty.Register("Data", typeof(object),
                                     typeof(BindingProxy));
}

现在，在 DataGrid 资源中添加它的一个实例，以便它可以继承 DataGrid 的 DataContext 并可以与其数据 DP 绑定:

Now, add an instance of it in DataGrid resources so that it can inherit the DataGrid's DataContext and can bind with its Data DP:

    <DataGrid>
        <DataGrid.Resources>
            <local:BindingProxy x:Key="proxy" Data="{Binding}"/>
        </DataGrid.Resources>
        <DataGrid.Columns>
            <DataGridTextColumn Visibility="{Binding Data.MyColumnVisibility,
                                                Source={StaticResource proxy}}"/>
        </DataGrid.Columns>
    </DataGrid>

---

第二，您可以使用 ElementName 或 x:Reference 引用 XAML 中的任何 UI 元素.但是，ElementName 仅适用于同一个可视化树，而 x:Reference 没有这样的约束.

---

Second, you can refer to any UI element in XAML using ElementName or x:Reference. However, ElementName works only in the same visual tree, whereas x:Reference doesn't have such constraints.

因此，我们也可以利用它来发挥我们的优势.在 XAML 中创建一个虚拟的 FrameworkElement，并将可见性设置为 collapsed.FrameworkElement 将从其父容器(可以是 Window 或 UserControl)继承 DataContext.

So, we can use that as well to our advantage. Create a dummy FrameworkElement in XAML with Visibility set to collapsed. The FrameworkElement will inherit the DataContext from its parent container, which can be a Window or UserControl.

并且可以在 DataGrid 中使用它:

And can use that in DataGrid:

    <FrameworkElement x:Name="dummyElement" Visibility="Collapsed"/>
    <DataGrid>
        <DataGrid.Columns>
            <DataGridTextColumn Header="Test"
                                Binding="{Binding Name}"
                                Visibility="{Binding DataContext.IsEnable,
                                          Source={x:Reference dummyElement}}"/>
        </DataGrid.Columns>
    </DataGrid>

这篇关于WPF 中 DataGridColumn 的绑定可见性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！