[C#][WPF] 修改datagrid的选中项后不再更新

Question

I'm new to C# and WPF recently. I fell into a difficult problem for me.

After editing the selected item in the datagrid, the selected item is no longer updated at all. I use custom class and binding it's member variable to datagrid.

(1) MyCustomCalss

public class DualString : IComparable
{
    public string Value { get; private set; }
    public string Origin { get; private set; }
    public string Text { get { return string.Format("{0}({1})", Value, Origin); } }

    public DualString()
    {
        Value = null;
        Origin = null;
    }

    public void Set(string value, string origin)
    {
        Value = value?.Trim();
        Origin = origin?.Trim();
    }
}

(2) DataGrid definition in xaml.

<DataGrid x:Name="dataGrid_tag" IsReadOnly="True" SelectionMode="Extended" SelectionChanged="dataGrid_tag_SelectionChanged" >
    <DataGrid.Columns>
        <DataGridTextColumn Binding="{Binding Text}" Header="Tag" Width="176"/>
    </DataGrid.Columns>
    <DataGrid.ContextMenu>
        <ContextMenu>
            <MenuItem x:Name="datagrid_tag_menu_modify" Header="Modify Tag" Click="datagrid_tag_menu_modify_Click"  />                        
        </ContextMenu>
    </DataGrid.ContextMenu>
</DataGrid>

(3) ItemSources was set by code, like below. Note that OhterList is used in another DataGrid.

private ObservableCollection<DualString> _TagList = new ObservableCollection<DualString>();
private ICollectionView _DataGridViewTag;

foreach (DualString tag in OtherList)
    _TagList.Add(tag);

_DataGridViewTag = CollectionViewSource.GetDefaultView(_TagList);
dataGrid_tag.ItemsSource = _DataGridViewTag;

(4) code is very simple, like below.

private void datagrid_tag_menu_modify_Click(object sender, RoutedEventArgs e)
{
    DualString selectedTag = dataGrid_tag.SelectedItem as DualString;
    selectedTag.Set("testValue", "testOrigin");
    _DataGridViewTag?.Refresh();
}

The first time I execute datagrid_tag_menu_modify_Click, dataGrid_tag.SelectedItem returns exactly correct instance. However, once I have modified the it, the dataGrid_tag.SelectedItem no longer changes at all.

I've no idea why this symptom is happened.

Answer 1

I found a solution myself. It is caused by multi-selection. After modifying item of item source, it seems that DataGrid holds the first selection item forever in it's SelectedItems list. I execute UnselectAll() before modifying item, then the problem went away.

private void datagrid_tag_menu_modify_Click(object sender, RoutedEventArgs e)
{
    DualString selectedTag = dataGrid_tag.SelectedItem as DualString;
    
    // execute UnselectAll() before modifying item.
    dataGrid_tag.UnselectAll();
    
    selectedTag.Set("testValue", "testOrigin");

    // re-select item.
    dataGrid_tag.SelectedItem = selectedTag;
    _DataGridViewTag?.Refresh();
}