如何基于ListViewItem中CompanyCode过滤Paycode_ComboBox选项

方法一：通过CollectionViewSource在XAML中实现过滤 #

在DataTemplate内部定义CollectionViewSource，绑定全局Paycodes集合后，通过过滤事件根据当前列表项的选中公司筛选数据。

修改后的XAML片段 #

<ListView Name="PaycodeMapping_ListView" 
          ItemsSource="{Binding Model.PaycodeMappings, NotifyOnSourceUpdated=True}">
    <ListView.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto"/>
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition Width="100"/>
                    <ColumnDefinition Width="125"/>
                </Grid.ColumnDefinitions>
                
                <!-- Company Code -->
                <ComboBox Name="CompanyCode_ComboBox"
                          Width="100"
                          HorizontalAlignment="Left"
                          VerticalAlignment="Center"
                          Margin="0"
                          ItemsSource="{Binding DataContext.CompanyList, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}"
                          SelectedItem="{Binding Path=Company, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
                          Grid.Row="0" Grid.Column="1"/>

                <!-- 定义过滤用的CollectionViewSource -->
                <CollectionViewSource x:Key="FilteredPaycodes" 
                                      Source="{Binding DataContext.Paycodes, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}"
                                      Filter="FilteredPaycodes_Filter"/>

                <!-- Paycode ComboBox -->
                <ComboBox Name="Paycode_ComboBox"
                          HorizontalAlignment="Left"
                          Width="125"
                          ItemsSource="{Binding Source={StaticResource FilteredPaycodes}}"
                          DisplayMemberPath="CodeDesc"
                          SelectedItem="{Binding Path=Paycode, NotifyOnSourceUpdated=True, Mode=TwoWay}"
                          Grid.Row="0" Grid.Column="2" />
            </Grid>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

后台添加过滤逻辑（UserControl代码-behind） #

private void FilteredPaycodes_Filter(object sender, FilterEventArgs e)
{
    if (e.Item is Paycode paycode && sender is CollectionViewSource cvs)
    {
        // 获取当前列表项的DataContext（即PaycodeMapping对象）
        var mapping = ((FrameworkElement)cvs.Parent).DataContext as PaycodeMapping;
        e.Accepted = mapping?.Company != null && paycode.CompanyCode == mapping.Company.CompanyCode;
    }
}

刷新过滤结果 #

在PaycodeMapping类的Company属性 setter 中添加刷新逻辑，确保切换公司时Paycode列表实时更新：

private Company _company;
public Company Company
{
    get => _company;
    set
    {
        if (_company != value)
        {
            _company = value;
            OnPropertyChanged();
            // 找到当前项的CollectionView并刷新
            var view = CollectionViewSource.GetDefaultView(FilteredPaycodes);
            view?.Refresh();
        }
    }
}

方法二：ViewModel层级实现过滤（MVVM友好） #

在PaycodeMapping类中新增过滤后的Paycodes属性，当选中公司变化时自动筛选数据，完全避免后台代码介入。

修改PaycodeMapping类 #

public class PaycodeMapping : INotifyPropertyChanged
{
    private readonly IEnumerable<Paycode> _allPaycodes;
    private Company _company;
    private IEnumerable<Paycode> _filteredPaycodes;

    // 构造时传入全局Paycodes集合
    public PaycodeMapping(IEnumerable<Paycode> allPaycodes)
    {
        _allPaycodes = allPaycodes;
        FilterPaycodes();
    }

    public Company Company
    {
        get => _company;
        set
        {
            if (_company != value)
            {
                _company = value;
                OnPropertyChanged();
                FilterPaycodes();
            }
        }
    }

    // 绑定给Paycode ComboBox的过滤后集合
    public IEnumerable<Paycode> FilteredPaycodes
    {
        get => _filteredPaycodes;
        private set
        {
            _filteredPaycodes = value;
            OnPropertyChanged();
        }
    }

    private void FilterPaycodes()
    {
        if (Company == null)
        {
            FilteredPaycodes = Enumerable.Empty<Paycode>();
            return;
        }
        FilteredPaycodes = _allPaycodes.Where(p => p.CompanyCode == Company.CompanyCode).ToList();
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

修改XAML绑定 #

将Paycode ComboBox的ItemsSource直接绑定到当前项的过滤后属性：

<!-- Paycode ComboBox -->
<ComboBox Name="Paycode_ComboBox"
          HorizontalAlignment="Left"
          Width="125"
          ItemsSource="{Binding FilteredPaycodes}"
          DisplayMemberPath="CodeDesc"
          SelectedItem="{Binding Path=Paycode, NotifyOnSourceUpdated=True, Mode=TwoWay}"
          Grid.Row="0" Grid.Column="2" />

内容的提问来源于stack exchange，提问作者BrianKE