c# – 如何调用UpdateSource()以在DataGrid上进行显式绑定？

我有一个DataGrid包含来自设置对象的信息.目前,DataGrid和设置对象之间存在双向绑定.但是,我想在其中放置一个“保存”按钮,仅在用户单击“保存”按钮时将DataGrid中所做的更改绑定到对象.但是,我不知道如何使用我的DataGrid为我的特定情况调用UpdateSource().

这是我的xaml.cs代码：

public void LoadDataFields(Data d)
        {
            Grid1.ItemsSource = d.Fields;
        }

private void SaveChanges(object sender, RoutedEventArgs e)
        {
            BindingExpression be = Grid1.GetBindingExpression(DataGrid.ItemsSourceProperty);
            be.UpdateSource();
        }

这是我的xaml代码：

<DataGrid x:Name="Grid1" 
                  IsReadOnly="False" 
                  Height="360" 
                  Margin="20,15,20,15" 
                  VerticalAlignment="Top" 
                  AutoGenerateColumns="False" 
                  CanUserAddRows="False" SelectionUnit="Cell"
                  ItemsSource="{Binding data}"
                  >

            <DataGrid.Columns>
                <DataGridTemplateColumn Header="Field">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <TextBox Text="{Binding Path=name, Mode=TwoWay, UpdateSourceTrigger=Explicit}"/>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
                <DataGridTemplateColumn Header="Length of Field">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <TextBox Text="{Binding Path=length, Mode=TwoWay, UpdateSourceTrigger=Explicit}"/>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>

是否有一种简单的方法来调用UpdateSource(),以便仅在单击“保存”按钮时才进行绑定？我的猜测是我只是为GetBindingExpression方法添加了错误的属性.

解决方法:

是的,有办法,但这不是一个非常简单的方法.首先,您需要2个辅助方法：

public static T GetVisualChild<T>(Visual parent) where T : Visual
{
    Visual visual;
    T child = default(T);

    int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
    for (int i = 0; i < childrenCount; i++)
    {
        visual = (Visual)VisualTreeHelper.GetChild(parent, i);
        child = visual as T;
        if (child == null)
        {
            child = GetVisualChild<T>(visual);
        }
        if (child != null)
        {
            break;
        }
    }
    return child;
}

public T FindVisualChild<T>(DependencyObject obj, string name) where T : DependencyObject
{
    DependencyObject child;
    FrameworkElement frameworkElement;
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
    {
        child = VisualTreeHelper.GetChild(obj, i);
        frameworkElement = child as FrameworkElement;
        if (child != null && child is T && frameworkElement != null && frameworkElement.Name == name)
        {
            return (T)child;
        }
        else
        {
            T childOfChild = FindVisualChild<T>(child, name);
            if (childOfChild != null)
            {
                return childOfChild;
            }
        }
    }

    return null;
}

然后你必须给你的绑定控件命名.例如“textBox”：

<DataGridTemplateColumn Header="Field">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <TextBox x:Name="textBox" Text="{Binding Path=name, Mode=TwoWay, UpdateSourceTrigger=Explicit}"/>
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTemplateColumn Header="Length of Field">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <TextBox x:Name="textBox" Text="{Binding Path=length, Mode=TwoWay, UpdateSourceTrigger=Explicit}"/>
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

然后在SaveChanges方法中,您可以使用以下代码：

private void SaveChanges(object sender, RoutedEventArgs e)
{
    DataGridRow dataGridRow;
    DataGridCellsPresenter dataGridCellsPresenter;
    DataGridCell dataGridCell;
    TextBox textBox;
    BindingExpression bindingExpression;

    for (int i = 0; i < Grid1.Items.Count; i++)
    {
        dataGridRow = (DataGridRow)Grid1.ItemContainerGenerator.ContainerFromIndex(i);
        dataGridCellsPresenter = GetVisualChild<DataGridCellsPresenter>(dataGridRow);
        for (int j = 0; j < Grid1.Columns.Count; j++)
        {
            dataGridCell = (DataGridCell)dataGridCellsPresenter.ItemContainerGenerator.ContainerFromIndex(j);
            textBox = FindVisualChild<TextBox>(dataGridCell, "textBox");
            if (textBox != null)
            {
                bindingExpression = BindingOperations.GetBindingExpression(textBox, TextBox.TextProperty);
                bindingExpression.UpdateSource();
            }
        }
    }
}

我希望它可以帮到你.

标签：c,wpf,xaml,datagrid,updatesourcetrigger
来源： https://codeday.me/bug/20190609/1204383.html