小贝子编程

显示数据表中已删除的行



所以我有一个DataTable，它绑定到XAML中的DataGrid。允许用户为表添加、修改和删除行。我想根据用户的操作，用特定的颜色标记行。例如，若用户添加了一行，则该行将标记为绿色。如果用户修改了一行，那么该行将被标记为橙色。如果用户删除该行，则该行将标记为红色。我遇到的问题是，一旦从视图模型调用row.Delete();，删除的行就不再可见。

有没有一种方法可以保持DataRow标记为要在DataGrid中删除？我知道如何实现行背景效果，这取决于用户的操作。唯一的问题是我不知道如何保持删除的行可见。其思想是，用户可以恢复更改或应用更改，这时应该实际删除挂起的删除行。

编辑(添加了如何更新行背景颜色的示例(：

<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding Path=Row.RowState}" Value="{x:Static data:DataRowState.Deleted}" />
<Condition Binding="{Binding RelativeSource={RelativeSource Mode=Self}, Path=IsSelected}" Value="False" />
</MultiDataTrigger.Conditions>
<MultiDataTrigger.Setters>
<Setter Property="Background" Value="IndianRed" TargetName="DGR_Border"/>
<Setter Property="Foreground" Value="Black"/>
<Setter Property="FontWeight" Value="Bold"/>
</MultiDataTrigger.Setters>
</MultiDataTrigger>

我认为，当用户标记行以进行删除时，您应该将其索引保存在某个位置(例如int[]数组或List<int>(，然后在用户处理完表后为该集合中的每个元素调用yourDataGridView.Rows.RemoveAt(index)。

也许类似于：

//Collection for rows indexes which will be deleted later
List<int> rowsToDelete = new List<int>();
//Call this when user want to delete element
private void MarkElementsToRemove()
{
if (yourDataGrid.SelectedItems.Count > 0)
{
//Get selected by user rows
for (int i = 0; i < yourDataGrid.SelectedItems.Count; ++i)
{
DataGridRow row = (DataGridRow)yourDataGrid.SelectedItems[i];
//Fill rows background with some color to mark them visually as "deleted"
row.Background = new SolidColorBrush(Color.FromRgb(255, 0, 0));
//Get row index to remove it later and add it to collection
rowsToDelete.Add(row.GetIndex());                        
}
}
}
// Call this when user finished work with DataGrid and items may be removed
private void RemoveMarkedElements()
{
foreach (int index in rowsToDelete)
{
yourDataGrid.Items.RemoveAt(index);
}

rowsToDelete.Clear();
}

您可以保存整个DataGridRow并调用yourDataGrid.Remove(wholeRow);，而不是索引。对于反向删除，只需通过删除颜色并从集合中删除行索引或整行来取消标记即可。

如果我理解正确，您需要使用Delete键，而不是删除行，而是在行上添加标记。在DataGrid中，您需要高亮显示用该标记标记的行的颜色。你还没有展示你的桌子，所以我将在我简单的调解中展示。

该示例使用BaseInpc和RelayCommand类。

除此之外，还使用了命令扩展方法：

using System.Windows.Input;
namespace Simplified
{
public static class CommandExtensionMethods
{
public static bool TryExecute(this ICommand command, object parameter)
{
bool can = command.CanExecute(parameter);
if (can)
command.Execute(parameter);
return can;
}
public static bool TryExecute(this ICommand command)
=> TryExecute(command, null);
}
}

ViewModel:

using Simplified;
using System.Data;
using System.Windows.Input;
namespace DeferredRowDeletion
{
public class DrdViewModel : BaseInpc
{
public DataTable Table { get; } = new DataTable();
public DrdViewModel()
{
Table.Columns.Add("Name", typeof(string));
Table.Columns.Add("Value", typeof(int));
Table.Columns.Add("Marked for deletion", typeof(bool));
foreach (var name in new string[] { "First", "Second", "Third", "Fourth", "Fifth" })
{
var row = Table.NewRow();
row[0] = name;
row[1] = Table.Rows.Count;
row[2] = Table.Rows.Count % 2 == 1;
Table.Rows.Add(row);
}
}
private ICommand _markRemoveChangeCommand;
private bool _isRemoveRowsImmediately;
public ICommand MarkRemoveChangeCommand => _markRemoveChangeCommand
?? (_markRemoveChangeCommand = new RelayCommand<DataRow>(
row => row[2] = !(bool)(row[2] ?? false),
row => !IsRemoveRowsImmediately
));
public bool IsRemoveRowsImmediately
{
get => _isRemoveRowsImmediately;
set => Set(ref _isRemoveRowsImmediately, value);
}
}
}

窗口XAML：

<Window x:Class="DeferredRowDeletion.DrdWindow"
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:local="clr-namespace:DeferredRowDeletion"
mc:Ignorable="d"
Title="DrdWindow" Height="450" Width="800">
<FrameworkElement.DataContext>
<local:DrdViewModel/>
</FrameworkElement.DataContext>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<CheckBox Content="Removw Rows Immediately"
IsChecked="{Binding IsRemoveRowsImmediately}"
Margin="5"/>
<DataGrid x:Name="dataGrid" Grid.Row="1"
ItemsSource="{Binding Table, Mode=OneWay}"
AutoGeneratingColumn="OnAutoGeneratingColumn"
CanUserDeleteRows="{Binding IsRemoveRowsImmediately}"
PreviewKeyDown="OnPreviewKeyDown">
<DataGrid.RowStyle>
<Style TargetType="DataGridRow">
<Style.Triggers>
<DataTrigger Binding="{Binding [Marked for deletion]}" Value="true">
<Setter Property="Background" Value="HotPink"/>
</DataTrigger>
</Style.Triggers>
</Style>
</DataGrid.RowStyle>
</DataGrid>
</Grid>
</Window>

窗口后面的代码：

using Simplified;
using System.Data;
using System.Windows;
using System.Windows.Input;
namespace DeferredRowDeletion
{
public partial class DrdWindow : Window
{
public DrdWindow()
{
InitializeComponent();
}
private void OnAutoGeneratingColumn(object sender, System.Windows.Controls.DataGridAutoGeneratingColumnEventArgs e)
{
if (e.PropertyName == "Marked for deletion")
e.Cancel = true;
}
private void OnPreviewKeyDown(object sender, System.Windows.Input.KeyEventArgs e)
{
if (e.Key == Key.Delete)
{
DrdViewModel viewModel = (DrdViewModel)DataContext;
var rowView = dataGrid.CurrentItem as DataRowView;
if (rowView != null && !rowView.IsEdit)
viewModel.MarkRemoveChangeCommand.TryExecute(rowView.Row);
}
}
}
}

如果你不能使用这个例子，那么写下原因并在问题的解释中添加细节。

答案由添加细节的澄清补充：

我想我应该提到，我使用绑定到DataTrigger的DataRow的RowState属性来更新行背景颜色。为问题添加了详细信息。

若要控制行的可见性，需要更改DataTable.DefaultView.RowStateFilter属性的值。这在ViewModel中并不难做到。

但另一个问题是RowState属性不会通知其更改。所以触发器绑定不会像那样工作。在我的示例中，我通过调用Items.Refresh ()解决了这个问题。也许您使用的是不同的解决方案，因为您还没有写过与此相关的任何问题。

using Simplified;
using System.Data;
using System.Windows.Input;
namespace DeferredRowDeletion
{
public class ShowDeletedRowsViewModel : BaseInpc
{
public DataTable Table { get; } = new DataTable();
public ShowDeletedRowsViewModel()
{
Table.Columns.Add("Name", typeof(string));
Table.Columns.Add("Value", typeof(int));
foreach (var name in new string[] { "First", "Second", "Third", "Fourth", "Fifth" })
{
var row = Table.NewRow();
row[0] = name;
row[1] = Table.Rows.Count;
Table.Rows.Add(row);
}
// Commits all the changes 
Table.AcceptChanges();
Table.Rows[1].Delete();
Table.Rows[3].Delete();
// Show Deleded Rows
IsVisibilityDelededRows = true;
}
private ICommand _markRemoveChangeCommand;
private bool _isVisibilityDelededRows;
public ICommand MarkRemoveChangeCommand => _markRemoveChangeCommand
?? (_markRemoveChangeCommand = new RelayCommand<DataRow>(
row => IsVisibilityDelededRows ^= true,
row => !IsVisibilityDelededRows
));
public bool IsVisibilityDelededRows
{
get => _isVisibilityDelededRows;
set => Set(ref _isVisibilityDelededRows, value);
}
protected override void OnPropertyChanged(string propertyName, object oldValue, object newValue)
{
base.OnPropertyChanged(propertyName, oldValue, newValue);
if (propertyName == nameof(IsVisibilityDelededRows))
{
// Change the row filter if the associated property has changed
if (IsVisibilityDelededRows)
{
Table.DefaultView.RowStateFilter |= DataViewRowState.Deleted;
}
else
{
Table.DefaultView.RowStateFilter &= ~DataViewRowState.Deleted;
}
}
}
}
}

<Window x:Class="DeferredRowDeletion.SdrWindow"
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:local="clr-namespace:DeferredRowDeletion" xmlns:data="clr-namespace:System.Data;assembly=System.Data"
mc:Ignorable="d"
Title="SdrWindow" Height="450" Width="800">
<FrameworkElement.DataContext>
<local:ShowDeletedRowsViewModel/>
</FrameworkElement.DataContext>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<StackPanel>
<CheckBox x:Name="cbAutoRefresh" Content="Auto Items.Refresh()" IsChecked="True" Margin="5"/>
<CheckBox Content="Visibility Deleded Rows"
IsChecked="{Binding IsVisibilityDelededRows}"
Margin="5"/>
</StackPanel>
<DataGrid x:Name="dataGrid" Grid.Row="1"
ItemsSource="{Binding Table, Mode=OneWay}"
PreviewKeyUp="OnPreviewKeyUp">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding Path=Row.RowState, Mode=OneWay}"
Header="RowState"/>
</DataGrid.Columns>
<DataGrid.RowStyle>
<Style TargetType="DataGridRow">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=Row.RowState}" Value="{x:Static data:DataRowState.Deleted}">
<Setter Property="Background" Value="HotPink"/>
</DataTrigger>
</Style.Triggers>
</Style>
</DataGrid.RowStyle>
</DataGrid>
</Grid>
</Window>

private void OnPreviewKeyUp(object sender, KeyEventArgs e)
{
if (e.Key == Key.Delete && cbAutoRefresh.IsChecked == true)
dataGrid.Items.Refresh();
}

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