Question

我正在使用这样的标准.NET DataGrid：

<DataGrid ItemsSource="{Binding Datensaetze}" AutoGenerateColumns="False">
 <DataGrid.Columns>
   <DataGridTextColumn Header="my col 1" Binding="{Binding MyCol1}"/>
   <DataGridTextColumn Header="my col 2" Binding="{Binding MyCol2}"/>
   <DataGridTextColumn Header="my col 3" Binding="{Binding MyCol3}"/>
 </DataGrid.Columns>
</DataGrid>

这很好用。现在我想在ViewModel中定义列，而不是在xaml中设置固定列，我想在运行中生成它们。但是，如果我尝试将列绑定到任何内容，我会收到错误，说

DataGrid.Columns是一个只读属性，无法绑定。

有没有办法将DataGrid列动态绑定到代码后面的某些内容？

Answer 1

是的，Columns属性是ReadOnly，所以我们不能直接绑定它。如果要绑定列，则可以尝试使用绑定的附加属性，然后更新列。

<强>更新
在CollectionChanged事件中使用变化增量。

public class DataGridColumnsBehavior
{
    public static readonly DependencyProperty BindableColumnsProperty =
        DependencyProperty.RegisterAttached("BindableColumns",
                                            typeof(ObservableCollection<DataGridColumn>),
                                            typeof(DataGridColumnsBehavior),
                                            new UIPropertyMetadata(null, BindableColumnsPropertyChanged));
    private static void BindableColumnsPropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
    {
        DataGrid dataGrid = source as DataGrid;
        ObservableCollection<DataGridColumn> columns = e.NewValue as ObservableCollection<DataGridColumn>;
        dataGrid.Columns.Clear();
        if (columns == null)
        {
            return;
        }
        foreach (DataGridColumn column in columns)
        {
            dataGrid.Columns.Add(column);
        }
        columns.CollectionChanged += (sender, e2) =>
        {
            NotifyCollectionChangedEventArgs ne = e2 as NotifyCollectionChangedEventArgs;
            if (ne.Action == NotifyCollectionChangedAction.Reset)
            {
                dataGrid.Columns.Clear();
                foreach (DataGridColumn column in ne.NewItems)
                {
                    dataGrid.Columns.Add(column);
                }
            }
            else if (ne.Action == NotifyCollectionChangedAction.Add)
            {
                foreach (DataGridColumn column in ne.NewItems)
                {
                    dataGrid.Columns.Add(column);
                }
            }
            else if (ne.Action == NotifyCollectionChangedAction.Move)
            {
                dataGrid.Columns.Move(ne.OldStartingIndex, ne.NewStartingIndex);
            }
            else if (ne.Action == NotifyCollectionChangedAction.Remove)
            {
                foreach (DataGridColumn column in ne.OldItems)
                {
                    dataGrid.Columns.Remove(column);
                }
            }
            else if (ne.Action == NotifyCollectionChangedAction.Replace)
            {
                dataGrid.Columns[ne.NewStartingIndex] = ne.NewItems[0] as DataGridColumn;
            }
        };
    }
    public static void SetBindableColumns(DependencyObject element, ObservableCollection<DataGridColumn> value)
    {
        element.SetValue(BindableColumnsProperty, value);
    }
    public static ObservableCollection<DataGridColumn> GetBindableColumns(DependencyObject element)
    {
        return (ObservableCollection<DataGridColumn>)element.GetValue(BindableColumnsProperty);
    }
}

然后，您可以将BindableColumns属性绑定到ColumnsCollection

<DataGrid AutoGenerateColumns="False"
          local:DataGridColumnsBehavior.BindableColumns="{Binding ColumnCollection}">
    <!-- ... -->
</DataGrid>

prism / mvvm：将列绑定到DataGrid

1 个答案: