WinUI3中WPF EventSetter的等效替代方案及DataGridComboBoxColumn事件处理

WinUI3中没有WPF里的EventSetter，可以通过以下几种方式实现类似需求：

方案1：使用XAML行为（Behaviors）绑定事件 #

先安装Microsoft.Xaml.Behaviors.WinUI NuGet包，再通过EventTrigger绑定SelectionChanged事件：

xmlns:interactivity="using:Microsoft.Xaml.Interactivity"
xmlns:core="using:Microsoft.Xaml.Interactions.Core"

<controls:DataGridComboBoxColumn x:Name="Whatever"
                                 DisplayMemberPath="Name"
                                 SelectedValuePath="Id"
                                 SelectedValueBinding="{Binding SelectedItemId}">
    <controls:DataGridComboBoxColumn.EditingElementStyle>
        <Style TargetType="ComboBox">
            <Setter Property="interactivity:Interaction.Behaviors">
                <interactivity:BehaviorCollection>
                    <core:EventTriggerBehavior EventName="SelectionChanged">
                        <core:InvokeCommandAction Command="{x:Bind ViewModel.ComboBoxSelectionChangedCommand}"
                                                 CommandParameter="{Binding}" />
                    </core:EventTriggerBehavior>
                </interactivity:BehaviorCollection>
            </Setter>
        </Style>
    </controls:DataGridComboBoxColumn.EditingElementStyle>
</controls:DataGridComboBoxColumn>

对应的ViewModel命令实现（MVVM模式）：

public ICommand ComboBoxSelectionChangedCommand { get; }

// 构造函数初始化
public YourViewModel()
{
    ComboBoxSelectionChangedCommand = new RelayCommand<ComboBoxSelectionChangedEventArgs>(OnComboBoxSelectionChanged);
}

private void OnComboBoxSelectionChanged(ComboBoxSelectionChangedEventArgs args)
{
    var selectedItem = args.AddedItems.FirstOrDefault();
    // 编写选中变更后的处理逻辑
}

方案2：通过DataGrid的CellEditEnded事件判断处理 #

若无需在选中瞬间触发，可在编辑结束时通过DataGrid的CellEditEnded事件处理：

<controls:DataGrid x:Name="MyDataGrid"
                   CellEditEnded="MyDataGrid_CellEditEnded">
    <controls:DataGridComboBoxColumn x:Name="Whatever" ... />
</controls:DataGrid>

后台代码：

private void MyDataGrid_CellEditEnded(object sender, DataGridCellEditEndedEventArgs e)
{
    if (e.Column == Whatever && e.EditingElement is ComboBox comboBox)
    {
        var selectedItem = comboBox.SelectedItem;
        // 编写选中变更后的处理逻辑
    }
}

方案3：自定义DataGridComboBoxColumn手动绑定事件 #

继承DataGridComboBoxColumn，重写生成编辑元素的方法，手动添加事件处理：

public class CustomDataGridComboBoxColumn : DataGridComboBoxColumn
{
    protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
    {
        var comboBox = (ComboBox)base.GenerateEditingElement(cell, dataItem);
        comboBox.SelectionChanged += ComboBox_SelectionChanged;
        return comboBox;
    }

    private void ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        var comboBox = (ComboBox)sender;
        var selectedItem = comboBox.SelectedItem;
        // 编写选中变更后的处理逻辑
        // 如需传递到页面，可定义自定义事件
        SelectionChanged?.Invoke(this, e);
    }

    // 自定义事件供页面绑定
    public event SelectionChangedEventHandler SelectionChanged;
}

XAML中使用自定义列：

<local:CustomDataGridComboBoxColumn x:Name="Whatever"
                                    SelectionChanged="CustomDataGridComboBoxColumn_SelectionChanged"
                                    ... />

后台页面事件处理：

private void CustomDataGridComboBoxColumn_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    // 编写选中变更后的处理逻辑
}

内容的提问来源于stack exchange，提问作者hellosantokki