如何对CollectionView进行多列筛选？

我有一个从数据库拉取大量数据的ListView，数据包含可用于筛选的字段，但目前只能单次按一列筛选，且两个筛选条件会互相覆盖。

初始单列筛选代码 #

以下是仅支持单列筛选的实现代码：

private bool prodAreaFilter(object item)
{
    return (item as PCdata).ProductionArea.IndexOf(((ComboBoxItem)prodAreaComboBox.SelectedItem).Content.ToString(), StringComparison.OrdinalIgnoreCase) >= 0;
}

private void prodArea_Combo_SelectionChanged(object sender, RoutedEventArgs e)
{
    CollectionView viewPA = (CollectionView)CollectionViewSource.GetDefaultView(lstView.ItemsSource);
    viewPA.Filter = prodAreaFilter;

    CollectionViewSource.GetDefaultView(lstView.ItemsSource).Refresh();

    //MessageBox.Show(((ComboBoxItem)prodAreaComboBox.SelectedItem).Content.ToString());

}

private bool typeFilter(object item)
{
    return (item as PCdata).Type.IndexOf(((ComboBoxItem)typeComboBox.SelectedItem).Content.ToString(), StringComparison.OrdinalIgnoreCase) >= 0;
}

private void type_Combo_SelectionChanged(object sender, RoutedEventArgs e)
{
    CollectionView viewType = (CollectionView)CollectionViewSource.GetDefaultView(lstView.ItemsSource);
    viewType.Filter = typeFilter;

    CollectionViewSource.GetDefaultView(lstView.ItemsSource).Refresh();

    //MessageBox.Show(((ComboBoxItem)typeComboBox.SelectedItem).Content.ToString());

}

首次尝试合并筛选逻辑 #

为解决筛选互相覆盖的问题，我尝试将两个筛选逻辑合并为单一方法，但该方法未处理ComboBox为空的场景：

private bool Filter(object item)
{
    return (item as PCdata).Type.IndexOf(((ComboBoxItem)typeComboBox.SelectedItem).Content.ToString(), StringComparison.OrdinalIgnoreCase) >= 0;
    (item as PCdata).ProductionArea.IndexOf(((ComboBoxItem)prodAreaComboBox.SelectedItem).Content.ToString(), StringComparison.OrdinalIgnoreCase) >= 0;
}


private void prodArea_Combo_SelectionChanged(object sender, RoutedEventArgs e)
{
    CollectionView viewPA = (CollectionView)CollectionViewSource.GetDefaultView(lstView.ItemsSource);
    viewPA.Filter = Filter;

    CollectionViewSource.GetDefaultView(lstView.ItemsSource).Refresh();

    //MessageBox.Show(((ComboBoxItem)prodAreaComboBox.SelectedItem).Content.ToString());

}

//private bool typeFilter(object item)
//{
//    return (item as PCdata).Type.IndexOf(((ComboBoxItem)typeComboBox.SelectedItem).Content.ToString(), StringComparison.OrdinalIgnoreCase) >= 0;
//}

private void type_Combo_SelectionChanged(object sender, RoutedEventArgs e)
{
    CollectionView viewType = (CollectionView)CollectionViewSource.GetDefaultView(lstView.ItemsSource);
    viewType.Filter = Filter;

    CollectionViewSource.GetDefaultView(lstView.ItemsSource).Refresh();

    //MessageBox.Show(((ComboBoxItem)typeComboBox.SelectedItem).Content.ToString());

}

最终解决方案（处理空筛选条件） #

添加逻辑处理其中一个ComboBox为空的情况，最终实现多条件组合筛选：

private void prodArea_Combo_SelectionChanged(object sender, RoutedEventArgs e)
{
    if (string.IsNullOrEmpty(typeComboBox.Text)) //若另一个下拉框为空，仅使用当前下拉框的筛选条件
    {
        CollectionView viewPA = (CollectionView)CollectionViewSource.GetDefaultView(lstView.ItemsSource);
        viewPA.Filter = obj => ((PCdata)obj).ProductionArea.Contains(((ComboBoxItem)prodAreaComboBox.SelectedItem).Content.ToString());
    }
    else
    {
        CollectionView viewPA = (CollectionView)CollectionViewSource.GetDefaultView(lstView.ItemsSource);
        viewPA.Filter = obj => ((PCdata)obj).ProductionArea.Contains(((ComboBoxItem)prodAreaComboBox.SelectedItem).Content.ToString()) &&
                                ((PCdata)obj).Type.Contains(((ComboBoxItem)typeComboBox.SelectedItem).Content.ToString());
    }
    
    CollectionViewSource.GetDefaultView(lstView.ItemsSource).Refresh();
}

private void type_Combo_SelectionChanged(object sender, RoutedEventArgs e)
{
    if (string.IsNullOrEmpty(prodAreaComboBox.Text))
    {
        CollectionView viewPA = (CollectionView)CollectionViewSource.GetDefaultView(lstView.ItemsSource);
        viewPA.Filter = obj => ((PCdata)obj).Type.Contains(((ComboBoxItem)typeComboBox.SelectedItem).Content.ToString());
    }
    else
    {
        CollectionView viewPA = (CollectionView)CollectionViewSource.GetDefaultView(lstView.ItemsSource);
        viewPA.Filter = obj => ((PCdata)obj).ProductionArea.Contains(((ComboBoxItem)prodAreaComboBox.SelectedItem).Content.ToString()) &&
                                ((PCdata)obj).Type.Contains(((ComboBoxItem)typeComboBox.SelectedItem).Content.ToString());
    }
    
    CollectionViewSource.GetDefaultView(lstView.ItemsSource).Refresh();
}

内容的提问来源于stack exchange，提问作者Alex D