根据 cmets 中的假设进行编辑：
如果像@bathineni 提到的那样，当集合中没有项目时，您想在DataGrid 上显示一个框，您可能需要使用RowDetailsTemplate 以外的机制来实现这一点。
我能想到的两个示例是设置 DataGrid 的样式，使其包含突出显示的 TextBlock 以显示此消息，另一个示例是创建一个网格，其中包含 DataGrid 和您想要在顶部显示的消息。
示例一：
为 DataGrid 设置样式
您可以找到very nice tutorial here，它将向您展示如何设置 DataGrid 内部的样式，类似于 Samuel 在这里的样式，总共有四个。
在 DataGrid 模板中，围绕 Grid 对象中的所有内容并创建要在其中显示的消息。
例如：（请原谅长码sn-p）
<Style TargetType="{x:Type DataGrid}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type DataGrid}">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition />
</Grid.RowDefinitions>
<Border
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
SnapsToDevicePixels="True"
Grid.Row="1"
Padding="{TemplateBinding Padding}">
<ScrollViewer Focusable="false" Name="DG_ScrollViewer">
<ScrollViewer.Template>
<ControlTemplate TargetType="{x:Type ScrollViewer}">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<!--Left Column Header Corner -->
<Button
Style="{StaticResource selectAllButtonTemplate}"
Command="{x:Static DataGrid.SelectAllCommand}"
Width="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Path=CellsPanelHorizontalOffset}"
Focusable="false"
Visibility="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Path=HeadersVisibility, Converter={x:Static DataGrid.HeadersVisibilityConverter}, ConverterParameter={x:Static DataGridHeadersVisibility.All}}" />
<!--Column Headers-->
<Primitives:DataGridColumnHeadersPresenter
Grid.Column="1"
Name="PART_ColumnHeadersPresenter"
Visibility="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Path=HeadersVisibility, Converter={x:Static DataGrid.HeadersVisibilityConverter}, ConverterParameter={x:Static DataGridHeadersVisibility.Column}}"/>
<!--DataGrid content-->
<ScrollContentPresenter x:Name="PART_ScrollContentPresenter" Grid.Row="1" Grid.ColumnSpan="2" CanContentScroll="{TemplateBinding CanContentScroll}" />
<Border Name="noItemsBorder" HorizontalAlignment="Center" VerticalAlignment="Center" Visibility="Hidden" SnapsToDevicePixels="True" Background="Coral" BorderBrush="DarkRed" BorderThickness="1" Grid.Row="1" Grid.ColumnSpan="2">
<TextBlock VerticalAlignment="Center" HorizontalAlignment="Center" Text="No items to display" Margin="20" />
</Border>
<ScrollBar
Grid.Row="0" Grid.RowSpan="2" Grid.Column="2" Name="PART_VerticalScrollBar"
Orientation="Vertical"
Maximum="{TemplateBinding ScrollableHeight}"
ViewportSize="{TemplateBinding ViewportHeight}"
Value="{Binding Path=VerticalOffset, RelativeSource={RelativeSource TemplatedParent}, Mode=OneWay}"
Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"/>
<Grid Grid.Row="2" Grid.Column="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}, Path=NonFrozenColumnsViewportHorizontalOffset}"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<ScrollBar
Grid.Column="1"
Name="PART_HorizontalScrollBar"
Orientation="Horizontal"
Maximum="{TemplateBinding ScrollableWidth}"
ViewportSize="{TemplateBinding ViewportWidth}"
Value="{Binding Path=HorizontalOffset, RelativeSource={RelativeSource TemplatedParent}, Mode=OneWay}"
Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"/>
</Grid>
</Grid>
<ControlTemplate.Triggers>
<DataTrigger Binding="{Binding Path=HasItems, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" Value="False">
<Setter TargetName="noItemsBorder" Property="Visibility" Value="Visible" />
</DataTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</ScrollViewer.Template>
<ItemsPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
</ScrollViewer>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}">Transparent</SolidColorBrush>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}">Transparent</SolidColorBrush>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}">Black</SolidColorBrush>
</Style.Resources>
<Style.Triggers>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
</Style.Triggers>
</Style>
在上面的示例中，您可以看到noItemsBorder 对象，这只是在DataGrid.HasItems 为false 时覆盖ScrollContentPresenter x:Name="PART_ScrollContentPresenter" 对象（使用触发器显示），另一种方法是在可见性上使用绑定属性，但为了清楚起见，我根据您的问题使用了触发器。
示例二：
一次性 TextBlock 覆盖
这将与上面的示例类似，但不是修改 DataGrid 样式，您只需将两个控件封装在一个 Grid 中。
虽然这可行，但需要将这段代码复制粘贴到任何你想使用它的地方，这并不理想。
代码如下：
<Grid>
<DataGrid Name="dg" ItemsSource="{Binding Path=DisplayItems}" />
<Border HorizontalAlignment="Center" VerticalAlignment="Center" Visibility="{Binding ElementName=dg, Path=HasItems, Converter={StaticResource booleanToVisibilityConverter}}" SnapsToDevicePixels="True" Background="Coral" BorderBrush="DarkRed" BorderThickness="1">
<TextBlock VerticalAlignment="Center" HorizontalAlignment="Center" Text="No items to display" Margin="20" />
</Border>
</Grid>
原帖：
我不确定您的 HasItems 使用的是什么，但请确保它是引发相应 PropertyChanged 事件的属性。
此代码按预期工作：
DataGrid XAML
<DataGrid Name="dataGrid" RowDetailsVisibilityMode="VisibleWhenSelected">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding Path=TextToDisplay}" />
</DataGrid.Columns>
<DataGrid.RowDetailsTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Name="txtnoitems" Text="No Records Found" Visibility="Collapsed"></TextBlock>
</StackPanel>
<DataTemplate.Triggers>
<DataTrigger Binding="{Binding HasItems}" Value="False">
<Setter TargetName="txtnoitems" Property="Visibility" Value="Visible"></Setter>
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
</DataGrid.RowDetailsTemplate>
</DataGrid>
（注意：我还删除了触发器绑定中的 {RelativeSource}，并将 RowDetailsVisibilityMode 属性设置为 DataGrid）
Some Item Class （用作子项）
public class SomeItem : INotifyPropertyChanged
{
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
public event PropertyChangedEventHandler PropertyChanged;
#region HasItems Definition
private bool _HasItems = true;
public bool HasItems
{
get
{
return _HasItems;
}
set
{
_HasItems = value;
OnPropertyChanged("HasItems");
}
}
#endregion // end of HasItems region
#region TextToDisplay Definition
private string _TextToDisplay = null;
public string TextToDisplay
{
get
{
return _TextToDisplay;
}
set
{
_TextToDisplay = value;
OnPropertyChanged("TextToDisplay");
}
}
#endregion // end of TextToDisplay region
public SomeItem(string blah)
{
TextToDisplay = blah;
}
}
用法：
dataGrid.Items.Add(new SomeItem("items"));
dataGrid.Items.Add(new SomeItem("items"));
dataGrid.Items.Add(new SomeItem("not items") { HasItems = false });
dataGrid.Items.Add(new SomeItem("items"));