WPF DataGrid添加行时数据不同步问题（滚动后数据异常）

这个问题是WPF DataGridUI虚拟化导致的常见问题：DataGrid默认只渲染当前可见区域的行，不在视图内的行延迟创建UI元素。当滚动到这些行时，CustomComboBox才会初始化，但如果数据模型或自定义控件的绑定逻辑有缺陷，就会出现数据不同步的情况。

核心修复步骤 #

1. 确保数据模型实现INotifyPropertyChanged #

Customer和Item类必须实现该接口，否则属性变更无法通知UI更新。示例代码：

public class Customer : INotifyPropertyChanged
{
    private string _name;
    private Item _item;

    public string Name
    {
        get => _name;
        set
        {
            _name = value;
            OnPropertyChanged();
        }
    }

    public Item Item
    {
        get => _item;
        set
        {
            _item = value;
            OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

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

public class Item : INotifyPropertyChanged
{
    private string _name;
    private string _type;

    public string Name
    {
        get => _name;
        set
        {
            _name = value;
            OnPropertyChanged();
        }
    }

    public string Type
    {
        get => _type;
        set
        {
            _type = value;
            OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

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

2. 修正CustomComboBox的依赖属性定义 #

自定义控件的依赖属性必须正确配置元数据，确保绑定双向生效并同步内部控件状态。示例：

public class CustomComboBox : UserControl
{
    public static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.Register(
            "SelectedItem", 
            typeof(Item), 
            typeof(CustomComboBox),
            new FrameworkPropertyMetadata(
                null, 
                FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
                (d, e) => ((CustomComboBox)d).CustomCombo.SelectedItem = e.NewValue));

    public static readonly DependencyProperty ItemsSourceProperty =
        DependencyProperty.Register(
            "ItemsSource", 
            typeof(IEnumerable<Item>), 
            typeof(CustomComboBox),
            new FrameworkPropertyMetadata(
                null,
                FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
                (d, e) => ((CustomComboBox)d).CustomCombo.ItemsSource = e.NewValue));

    public Item SelectedItem
    {
        get => (Item)GetValue(SelectedItemProperty);
        set => SetValue(SelectedItemProperty, value);
    }

    public IEnumerable<Item> ItemsSource
    {
        get => (IEnumerable<Item>)GetValue(ItemsSourceProperty);
        set => SetValue(ItemsSourceProperty, value);
    }

    // 其他原有代码...
}

3. 确认集合类型为ObservableCollection #

用于绑定的CustomersList必须是ObservableCollection<Customer>，而非普通List，这样新增元素时才能自动通知DataGrid更新：

public ObservableCollection<Customer> CustomersList { get; set; } = new ObservableCollection<Customer>();

4. 验证虚拟化影响（可选测试步骤） #

如果以上步骤无效，可临时关闭DataGrid虚拟化确认问题根源：

<DataGrid x:Name="DG" ... VirtualizingPanel.IsVirtualizing="False" />

注意：关闭虚拟化会降低大数据量下的性能，仅用于测试，最终建议保留虚拟化并修复绑定逻辑。

内容的提问来源于stack exchange，提问作者MElSawy