记住WPF DataGrid排序顺序 [英] Remember WPF DataGrid sort order

问题描述

这是这个问题的延续。

我有一个包含动态创建项目的 TabControl 的wpf窗口。该 TabControl 的 ItemSource 绑定到组列表 s。这些组包含在 TabPage 中的 DataGrid 中显示的元素列表。

I have a wpf window that contains a TabControl with dynamically created items. The ItemSource of this TabControl is binded to a list of Groups. These groups contain a list of elements that is displayed in a DataGrid on the TabPage.

XAML：

<Window x:Name="window" x:Class="TestWpf.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:vm="clr-namespace:TestWpf"
    Title="MainWindow" Height="350" Width="525">
    <TabControl x:Name="tabControl" BorderThickness="0" ItemsSource ="{Binding Groups, ElementName=window, NotifyOnSourceUpdated=True}">
        <TabControl.ItemTemplate>
            <DataTemplate DataType="{x:Type vm:Group}">
                <TextBlock Padding="2" Text="{Binding Name}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
            </DataTemplate>
        </TabControl.ItemTemplate>
        <TabControl.ContentTemplate>
            <DataTemplate x:Name="contentTemplate" DataType="{x:Type vm:Group}">
                <DataGrid x:Name="dgElements" ItemsSource="{Binding Elements, BindsDirectlyToSource=True}" DockPanel.Dock="Top" AutoGenerateColumns="False" >
                    <DataGrid.Columns>
                        <DataGridTextColumn x:Name="clmName" Header="Name" Binding="{Binding Name}" IsReadOnly="True" CanUserReorder="False" />
                    <DataGridTextColumn x:Name="clmDesc" Header="Description" Binding="{Binding Description}" IsReadOnly="True" CanUserReorder="False" />
                    </DataGrid.Columns>
                </DataGrid>
            </DataTemplate>
        </TabControl.ContentTemplate>
    </TabControl>
</Window>

这一切正常。

DataGrid 允许多列开箱即用。但是不幸的是，如果我在标签页之间切换，排序就会丢失。

我希望为每个tabpage / datagrid 维护多列排序。

The DataGrid allows multi-column sort out of the box. But unfortunatly, if I switch between the tabpages, the sorting is lost.
I want that the multi-column sorting is maintained for each tabpage/datagrid.

可以将 SortDirection DataGridTextColumn 绑定到属性，但这不记住列的排序顺序。调试我发现当我切换标签页时， SortDirection 在新的 ItemSource 被设置，所以我不能存储这个。

It is possible to bind the SortDirection of DataGridTextColumn to a property, but that does not remember the sort order of the columns. And debugging I found that when I switch the tabpage, the SortDirection is reset before the new ItemSource is set, so I can't store this.

问题是：如何保持每个tabpage / datagrid的多列排序设置？

推荐答案

阅读了很多文章后，几乎解决了我的问题，我终于找到了一个解决方案。
我从 DataGrid 继承了我自己的类，并存储 SortDescriptions 每个 ItemSource 在字典中：

After reading a lot of articles only almost solving my problem, I finally found a solution.
I inherited my own class from DataGrid and stored the SortDescriptions per ItemSource in a Dictionary:

public class SortKeepingDataGrid : DataGrid
{
    // Dictionary to keep SortDescriptions per ItemSource
    private readonly Dictionary<object, List<SortDescription>> m_SortDescriptions =
        new Dictionary<object, List<SortDescription>>();

    protected override void OnSorting(DataGridSortingEventArgs eventArgs)
    {
        base.OnSorting(eventArgs);
        UpdateSorting();
    }
    protected override void OnItemsSourceChanged(IEnumerable oldValue, IEnumerable newValue)
    {
        base.OnItemsSourceChanged(oldValue, newValue);

        ICollectionView view = CollectionViewSource.GetDefaultView(newValue);
        view.SortDescriptions.Clear();

        // reset SortDescriptions for new ItemSource
        if (m_SortDescriptions.ContainsKey(newValue))
            foreach (SortDescription sortDescription in m_SortDescriptions[newValue])
            {
                view.SortDescriptions.Add(sortDescription);

                // I need to tell the column its SortDirection,
                // otherwise it doesn't draw the triangle adornment
                DataGridColumn column = Columns.FirstOrDefault(c => c.SortMemberPath == sortDescription.PropertyName);
                if (column != null)
                    column.SortDirection = sortDescription.Direction;
            }
    }

    // Store SortDescriptions in dictionary
    private void UpdateSorting()
    {       
        ICollectionView view = CollectionViewSource.GetDefaultView(ItemsSource);
        m_SortDescriptions[ItemsSource] = new List<SortDescription>(view.SortDescriptions);
    }
}

所以，基本上每当用户改变排序时，我调用 UpdateSorting 并存储当前 SortDescription s在每个 ItemSource 字典。

当 ItemSource 已更改时，我查找 SortDescription 以正确的顺序重置它们。

So, basically, whenever the user changes the sorting, I call UpdateSorting and store the current SortDescriptions in the per ItemSource dictionary.
When the ItemSource has changed, I look up the SortDescriptions and reset them in the correct order.

棘手的部分是找到正确的 DataGridColumn 来设置它的 SortDirection 。这是必要的画三角形装饰。我这里依赖于 SortMemberPath 和 PropertyName 的相等性。最终可能需要一种更通用的方法。

The tricky part is finding the correct DataGridColumn to set its SortDirection. This is necessary to draw the triangled adornment. I here rely on the equality of SortMemberPath and PropertyName. Eventually a more generic approach could be necessary.

在XAML中，我将替换为 DataGrid c> SortKeepingDataGrid ，现在每个标签页都存储排序。

In the XAML I replaced the DataGrid with my SortKeepingDataGrid and now the sorting is stored per tabpage.

由于我找不到任何其他解决方案，也许这将帮助别人。

Since I could not find any other solution, maybe this will help others too.

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