如何在数据网格行标题中添加分组行的所有列值

Question

我试图在这个 WPF 应用程序中实现的是总结列“大小”的所有值，该列按页眉上的家庭分组。数据网格中是否有任何方法可以对特定类别下分组的所有行的列进行求和？

XAML

<Window.Resources>
    <Style x:Key="GroupHeaderStyle" TargetType="{x:Type GroupItem}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type GroupItem}">
                    <Expander x:Name="exp" IsExpanded="False" Background="White" Foreground="Black">
                        <Expander.Header>
                            <StackPanel Orientation="Horizontal">
                                <TextBlock Text="{Binding Name}" />
                                <TextBlock Name="TotalSize" Text="Total size here"  Margin="290 0 0 0" />
                            </StackPanel>
                        </Expander.Header>
                        <ItemsPresenter Margin="20 0 0 0" />
                    </Expander>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>

C#

public partial class MainWindow : Window        
{      
    ObservableCollection<DownloadManager> dManager = new ObservableCollection<DownloadManager>();

    public MainWindow()
    {
        InitializeComponent();
        XmlDocument doc = new XmlDocument();
        doc.Load("dm.xml");
        XmlNodeList xnList = doc.SelectNodes("/root/repository/MEDIA");

        foreach (XmlNode media in xnList)
        {
            string PRODUCT = media["PRODUCT"].InnerText;
            string SIZE = media["SIZE"].InnerText;
            string MEDIASTATUS = media["MEDIASTATUS"].InnerText;
            string FAMILY = media["FAMILY"].InnerText;
            dManager.Add(new DownloadManager { Name = PRODUCT, Size = SIZE, Description = MEDIASTATUS, Family = FAMILY });
        }

        ListCollectionView collection = new ListCollectionView(dManager);
        collection.GroupDescriptions.Add(new PropertyGroupDescription("Family"));
        dataGrid.ItemsSource = collection;             
    }
}

public class DownloadManager
{
    public string Name { get; set; }
    public string Size { get; set; }
    public string Description { get; set; }
    public string Family { get; set; }
}

XML

<root>
  <repository >
    <MEDIA>
      <PRODUCT>MS Office</PRODUCT>
      <FAMILY>Paid</FAMILY>
      <SIZE>1056</SIZE>
      <MEDIASTATUS>LIVE</MEDIASTATUS>
    </MEDIA>

    <MEDIA>
      <PRODUCT>Matlab</PRODUCT>
      <FAMILY>Paid</FAMILY>
      <SIZE>2096</SIZE>
      <MEDIASTATUS>LIVE</MEDIASTATUS>
    </MEDIA>

    <MEDIA>
      <PRODUCT>Winzip</PRODUCT>
      <FAMILY>Free</FAMILY>
      <SIZE>119</SIZE>
      <MEDIASTATUS>LIVE</MEDIASTATUS>
    </MEDIA>

    <MEDIA>
      <PRODUCT>Team Viewer</PRODUCT>
      <FAMILY>Free</FAMILY>
      <SIZE>256</SIZE>
      <MEDIASTATUS>LIVE</MEDIASTATUS>
    </MEDIA>

    <MEDIA>
      <PRODUCT>Coral Draw</PRODUCT>
      <FAMILY>Paid</FAMILY>
      <SIZE>3110</SIZE>
      <MEDIASTATUS>LIVE</MEDIASTATUS>
    </MEDIA>

    <MEDIA>
      <PRODUCT>Photoshop</PRODUCT>
      <FAMILY>Free</FAMILY>
      <SIZE>2056</SIZE>
      <MEDIASTATUS>LIVE</MEDIASTATUS>
    </MEDIA>

  </repository>
</root>

Answer 1

我能想到的最简洁的解决方案是创建一个 Converter 类 - 实现 Convert 方法来循环分组项目，对 Size 值求和，并根据需要格式化返回字符串：

public class SumGroupConverter : IValueConverter
{
     public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
     {
          GroupItem groupItem = value as GroupItem;
          CollectionViewGroup collectionViewGroup = groupItem.Content as CollectionViewGroup;
          int sum = 0;

          foreach (var item in collectionViewGroup.Items)
          {
              DownloadManager dman = item as DownloadManager;
              int size = 0;
              int.TryParse(dman.Size, out size);
              sum += size;
          }

          return string.Format("Total size: {0}", sum);
      }

      public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
      {
          throw new NotImplementedException();
      }
  }

然后，假设您的 xaml 中有一行如 xmlns:local="clr-namespace:WpfApplication1"，那么您可以将以下内容添加到您的 Window.Resources：

<local:SumGroupConverter x:Key="SumTitle"/>

对于TextBox 内的Expander：

<TextBlock 
    Name="TotalSize" 
    Text="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type GroupItem}}, Converter={StaticResource ResourceKey=SumTitle}}"  
    Margin="290 0 0 0"/>

结果：