在非主要TabItem中时，绑定在DataGrid列标题中不起作用 [英] Binding not working in DataGrid column header when inside non-primary TabItem

问题描述

我有一个 DataGrid ，它的标题中有一个绑定的UI控件。绑定到视图模型中的字段。网格位于 TabControl 内部。当网格位于选项卡控件中的初始选项卡上时，一切正常。

I have a DataGrid which has a bound UI control in its header. The binding is to a a field in a view model. The grid is inside a TabControl. When the grid is on the initial tab in the tab control, all works well.

但是，当网格不在初始选项卡上时，似乎没有绑定地点。没有控制台输出，没有调用值转换器，跟踪级别的日志记录不报告任何内容。

However, when the grid isn't on the initial tab, no binding seems to take place. There's no console output, value converters aren't being invoked, trace level logging isn't reporting anything.

这里有一个简单的，可重现的示例：

Here's a trivial, reproducible example:

public class ViewModel : INotifyPropertyChanged
{
    private string _camel = "Bertie";

    public string Camel
    {
        get => _camel;
        set
        {
            if (value == _camel) return;
            _camel = value;
            OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    [NotifyPropertyChangedInvocator]
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

MainWindow.xaml

MainWindow.xaml

<Window x:Class="ThingsWithHumps.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:thingsWithHumps="clr-namespace:ThingsWithHumps"
        mc:Ignorable="d"
        Height="350" Width="350">
    <Window.DataContext>
        <thingsWithHumps:ViewModel/>
    </Window.DataContext>
    <TabControl>
        <!-- This TabItem prevents the TextBlock being bound -->
        <TabItem Header="Troublesome tab"/>
        <TabItem Header="Humps">
            <DataGrid AutoGenerateColumns="False">
                <DataGrid.Columns>
                    <DataGridTemplateColumn>
                        <DataGridTemplateColumn.Header>

                            <!-- Troublesome binding -->
                            <TextBlock Text="{Binding Path=DataContext.Camel,
                                   UpdateSourceTrigger=PropertyChanged,
                                   RelativeSource={RelativeSource FindAncestor,
                                       AncestorType={x:Type Window}}}" />
                        </DataGridTemplateColumn.Header>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
            </DataGrid>
        </TabItem>
    </TabControl>
</Window>

MainWindow.xaml.cs

MainWindow.xaml.cs

namespace ThingsWithHumps
{
    public partial class MainWindow 
    {
        public MainWindow() => InitializeComponent();
    }
}

推荐答案

之后试图解决您的问题几分钟而没有成功，我找到了一个在线解决方案，似乎可以解决您的问题。

After trying to fix your issue for a few minutes without success, i've found a solution online which seems to fix your issue.

> http://www.thomaslevesque.com/2011/03/21/wpf-how-to-bind-to-data-when-the- datacontext-is-not-herited /

我已经尝试过了，并且可以使用！

I've tried it and it works! Good luck!

这里有xaml代码

<TabControl>
    <!-- This TabItem prevents the TextBlock being bound -->
    <TabItem Header="Troublesome tab"/>
    <TabItem Header="Humps">
        <DataGrid AutoGenerateColumns="False">
            <DataGrid.Resources>
                <local:BindingProxy x:Key="proxy" Data="{Binding}" />
            </DataGrid.Resources>
            <DataGrid.Columns>
                <DataGridTemplateColumn>

                    <DataGridTemplateColumn.Header>

                        <!-- Troublesome binding -->
                        <TextBlock Text="{Binding Path=Data.Camel,
                               UpdateSourceTrigger=PropertyChanged,
                               Source={StaticResource proxy}}" />
                    </DataGridTemplateColumn.Header>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
    </TabItem>
</TabControl>

和绑定代理类：

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); }
    }

    // Using a DependencyProperty as the backing store for Data.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty DataProperty =
        DependencyProperty.Register("Data", typeof(object), typeof(BindingProxy), new UIPropertyMetadata(null));
}

这篇关于在非主要TabItem中时，绑定在DataGrid列标题中不起作用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！