如何在WPF中将值设置到自定义DataGridBound列中

Question

由于无法将值粘贴到DataGridTemplateColumn中，我发现一些建议可以创建自己的列类，派生自DataGridBoundColumn。 以下示例在不使用模板的情况下向列添加了DatePicker。

然而，这个示例不允许我使用DatePicker手动设置值，我不确定为什么。我认为与绑定有关。它会加载初始绑定到它上面的日期值，所以它已经做到了一半。

有趣的是，使用其他一些帮助类，我也可以粘贴日期，这也是最初的目的。 我只是不想破坏其他东西。:-)

有什么想法可以使datepicker选定的值正确绑定？

class MyDateColumn : DataGridBoundColumn 
{
    public string DateFormat { get; set; }
    protected override void CancelCellEdit(FrameworkElement editingElement, object uneditedValue)
    {
        DatePicker dp = editingElement as DatePicker;
        if (dp != null)
        {
            dp.SelectedDate = DateTime.Parse(uneditedValue.ToString());
        }
    }
    protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
    {
        DatePicker dp = new DatePicker();
        Binding b = new Binding();
        Binding bb = this.Binding as Binding;
        b.Path = bb.Path;
        b.Source = DatePicker.SelectedDateProperty;
        if (DateFormat != null)
        {
            DateTimeConverter dtc = new DateTimeConverter();
            b.Converter = dtc;
            b.ConverterParameter = DateFormat;
        }
        dp.SetBinding(DatePicker.SelectedDateProperty, this.Binding);

        return dp;
    }

    protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
    {
        TextBlock txt = new TextBlock();
        Binding b = new Binding();
        Binding bb = this.Binding as Binding;
        b.Path = bb.Path;
        b.Source = cell.DataContext;

        if (DateFormat != null)
        {
            DateTimeConverter dtc = new DateTimeConverter();
            b.Converter = dtc;
            b.ConverterParameter = DateFormat;
        }
        txt.SetBinding(TextBlock.TextProperty, this.Binding);
        return txt;
    }

    protected override object PrepareCellForEdit(FrameworkElement editingElement, RoutedEventArgs editingEventArgs)
    {
        DatePicker dp = editingElement as DatePicker;
        if (dp != null)
        {
            DateTime? dt = dp.SelectedDate;
            if (dt.HasValue)
                return dt.Value;
        }
        return DateTime.Today;
    }

    protected override bool CommitCellEdit(FrameworkElement editingElement)
    {
        DatePicker dp = editingElement as DatePicker;
        dp.SelectedDate = DateTime.Today.AddYears(1);

        return true;
        //return base.CommitCellEdit(editingElement);
    }
}

- Tara

Answer 1

解决方案是对CommitCellEdit（）进行修改...

    protected override bool CommitCellEdit(FrameworkElement editingElement)
    {
        DatePicker dp = editingElement as DatePicker;
        DateTime dt;
        try
        {
            dt = Convert.ToDateTime(dp.Text);
            dp.SelectedDate = dt;
        }
        catch (FormatException)
        {
            dp.Text = String.Empty;
        }


        BindingExpression binding = editingElement.GetBindingExpression(DatePicker.SelectedDateProperty);
        if (binding != null)
            binding.UpdateSource();
        return true;
        //return base.CommitCellEdit(editingElement);
    }

原始代码和帮助来自以下链接...

http://leeontech.wordpress.com/2009/01/21/creating-datagriddatecolumn-for-datagrid/#comment-1033

感谢 Lee 创建示例并提供帮助！

- Tara

Answer 2

我发现了一种更简单和通用的解决方法。与其为每个模板列创建自定义列，我创建了一个从DataGridTemplateColumn继承的自定义列。这将解决您想要拥有的所有模板的问题。自定义列具有附加的BindingPath属性，在其中指定要使用复制的数据更新绑定对象上的哪个属性。显然，绑定对象需要实现INotifyPropertyChanged接口。一旦源已更新，您的控件将自动更新。

以下是自定义列代码：

using System.Reflection;
using Microsoft.Windows.Controls;

namespace Bartosz.Wojtowicz.Wpf
{
    public class PastableDataGridTemplateColumn : DataGridTemplateColumn
    {
        public string BindingPath { get; set; }

        public override void OnPastingCellClipboardContent(object item, object cellContent)
        {
            if (item != null)
            {
                PropertyInfo propertyInfo = item.GetType().GetProperty(BindingPath);
                if (propertyInfo != null)
                {
                    propertyInfo.SetValue(item, cellContent, null);
                }
            }
        }
    }
}

以下是如何在XAML中使用它的方法：

 <local:PastableDataGridTemplateColumn Header="Value" BindingPath="ValueView" ClipboardContentBinding="{Binding ValueView}" >
  <local:PastableDataGridTemplateColumn.CellTemplate >
    <DataTemplate>
      <!-- your template ... -->
    </DataTemplate>
  </local:PastableDataGridTemplateColumn.CellTemplate>
  <local:PastableDataGridTemplateColumn.CellEditingTemplate>
    <DataTemplate>
      <!-- your template ... -->
    </DataTemplate>
  </local:PastableDataGridTemplateColumn.CellEditingTemplate>
</local:PastableDataGridTemplateColumn>

- Bartosz Wójtowicz