WPF DataGrid 多值綁定：使用 MultiBinding 與 IMultiValueConverter 計算列差值

場景

DataGrid 綁定實體集合 List<User>，實體含 CurrentMoney、PayMoney，需顯示第三列 CurrentMoney - PayMoney，實體無此屬性。

解決方案：MultiBinding + 轉換器

1. 實現 IMultiValueConverter

public class MoneyDiffConverter : IMultiValueConverter {
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) {
        if (values.Length == 2 && values[0] is decimal && values[1] is decimal) {
            return (decimal)values[0] - (decimal)values[1];
        }
        return DependencyProperty.UnsetValue;
    }
    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) {
        throw new NotSupportedException();
    }
}

2. XAML 註冊資源並綁定

<Window.Resources>
    <local:MoneyDiffConverter x:Key="MoneyDiffConverter"/>
</Window.Resources>

<DataGrid ItemsSource="{Binding Users}" AutoGenerateColumns="False">
    <DataGrid.Columns>
        <DataGridTextColumn Header="當前金額" Binding="{Binding CurrentMoney}"/>
        <DataGridTextColumn Header="支付金額" Binding="{Binding PayMoney}"/>
        <DataGridTextColumn Header="餘額">
            <DataGridTextColumn.Binding>
                <MultiBinding Converter="{StaticResource MoneyDiffConverter}" StringFormat="F2">
                    <Binding Path="CurrentMoney"/>
                    <Binding Path="PayMoney"/>
                </MultiBinding>
            </DataGridTextColumn.Binding>
        </DataGridTextColumn>
    </DataGrid.Columns>
</DataGrid>

替代方案對比

建議

業務復雜、多界面復用時首選 MultiBinding，保持實體純粹。