WPF DataGrid修改列值后目标数据不显示的问题排查与解决

在C# WPF项目中使用DataGrid，ItemsSource从后台代码填充时遇到两个问题：

• 为某列设置默认值后，该值需双击列才会显示；
• 在CellEndEdit事件中修改另一列的值时，无法实时显示，需双击进入编辑状态才可见。

已尝试以下刷新方法均无效：

DGR_SUB_INVOLST.Items.Refresh();
DGR_SUB_INVOLST.BeginEdit();
DGR_SUB_INVOLST.CommitEdit();
DGR_SUB_INVOLST.InvalidateVisual();
DGR_SUB_INVOLST.UpdateLayout();

相关代码 #

XAML #

<DataGrid x:Name="DGR_SUB_INVOLST"
          EnableColumnVirtualization="True"
          EnableRowVirtualization="True"
          VirtualizingPanel.IsVirtualizing="True"
          VirtualizingPanel.VirtualizationMode="Recycling"
          ScrollViewer.CanContentScroll="False"
          ItemsSource="{Binding ALL_DATA_INVO, UpdateSourceTrigger=PropertyChanged,Mode=TwoWay}"
          AutoGenerateColumns="False"  FlowDirection="RightToLeft" CellEditEnding="DGR_SUB_INVOLST_CellEditEnding" SelectionUnit="Cell">
    <DataGrid.Columns >
        <DataGridTextColumn Header="ردیف" x:Name="RADIF_COL"  Binding="{Binding RADIF}" MinWidth="40" Visibility="Hidden"/>

        <DataGridComboBoxColumn x:Name="ANBAR_COL" Width="80" Header=" انبار " SelectedValueBinding="{Binding CODE,UpdateSourceTrigger=PropertyChanged}" DisplayMemberPath="NAMES" SelectedValuePath="CODE">
            <DataGridComboBoxColumn.EditingElementStyle>
                <Style TargetType="{x:Type ComboBox}">
                    <Setter Property="IsEditable" Value="True"/>
                    <Setter Property="ItemsPanel" Value="{StaticResource VSP}"/>
                    <Setter Property="ScrollViewer.CanContentScroll" Value="True"/>
                    <Setter Property="VirtualizingStackPanel.IsVirtualizing" Value="True"/>
                    <Setter Property="VirtualizingStackPanel.VirtualizationMode" Value="Recycling"/>
                </Style>
            </DataGridComboBoxColumn.EditingElementStyle>
        </DataGridComboBoxColumn>

        <DataGridTextColumn Header="نام کالا" x:Name="NAME_COL" Binding="{Binding NAME,UpdateSourceTrigger=PropertyChanged}" Visibility="Visible" MinWidth="180"/>
        <DataGridTextColumn Header="کد کالا" x:Name="CODEKALA_COL" Binding="{Binding CODEKALA,UpdateSourceTrigger=PropertyChanged}" Visibility="Hidden" MinWidth="80"/>
    </DataGrid.Columns>
</DataGrid>

C# #

private void DGR_SUB_INVOLST_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
    if (DGR_SUB_INVOLST != null)
    {
        if (DGR_SUB_INVOLST.Items.Count > 0)
        {
            (e.Row.Item as INVOMonitor).CODE = 1;
            //Refresh here :
            DGR_SUB_INVOLST.Items.Refresh();
            DGR_SUB_INVOLST.BeginEdit();
            DGR_SUB_INVOLST.CommitEdit();
            DGR_SUB_INVOLST.InvalidateVisual();
            DGR_SUB_INVOLST.UpdateLayout();
        }
    }
}

解决方案 #

问题根源是INVOMonitor类未实现INotifyPropertyChanged接口，WPF数据绑定依赖该接口监听属性变化，自动同步界面显示。

1. 修改INVOMonitor类实现接口 #

public class INVOMonitor : INotifyPropertyChanged
{
    private int _code;
    public int CODE
    {
        get => _code;
        set
        {
            if (_code != value)
            {
                _code = value;
                OnPropertyChanged(nameof(CODE));
            }
        }
    }

    // 其他需要绑定的属性（如RADIF、NAME等）都要按此方式实现
    private int _radif;
    public int RADIF
    {
        get => _radif;
        set
        {
            if (_radif != value)
            {
                _radif = value;
                OnPropertyChanged(nameof(RADIF));
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

2. 简化CellEditEnding事件代码 #

移除所有手动刷新代码，属性变更会自动通知界面更新：

private void DGR_SUB_INVOLST_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
    if (e.Row.Item is INVOMonitor item)
    {
        item.CODE = 1;
    }
}

原理说明 #

WPF绑定机制通过INotifyPropertyChanged的PropertyChanged事件，在属性值变更时通知DataGrid列更新显示。若实体类未实现该接口，即使修改属性值，界面也无法感知变化；手动刷新方法在虚拟化开启场景下往往无效，且不符合WPF绑定规范。

内容的提问来源于stack exchange，提问作者Learner