双击WPF数据网格中的单个单元格，如何更改它的值？

Question

I have a datagrid that lists the status of a couple things and displays either "True" or "False". When I double click on a cell, I want to toggle what that cell displays. I've tried using a number of properties for my datagrid, such as currentItem, SelectedItem, SelectedValue, and SelectedUnit, but none of these have worked.

<DataGrid x:Name="dataGrid1" IsReadOnly="True" IsManipulationEnabled="False" Width="250" Height="468"  Margin="795,15,18,15" 
          VerticalAlignment="Top" AutoGenerateColumns="False" CanUserAddRows="False" MouseDoubleClick="DoubleClick" 
          ItemsSource="{Binding Availability}">
    <DataGrid.Columns>
        <DataGridTextColumn Header="Number" Binding="{Binding Key, UpdateSourceTrigger=PropertyChanged}" Width="Auto"/>
        <DataGridTextColumn Header="Status1" Binding="{Binding Value1, UpdateSourceTrigger=PropertyChanged}" Width="Auto"/>
        <DataGridTextColumn Header="Status2" Binding="{Binding Value2, UpdateSourceTrigger=PropertyChanged}" Width="*"/>
    </DataGrid.Columns>
</DataGrid>

Here's the event in my codebehind:

private void DoubleClick(object sender, MouseButtonEventArgs e)
{
    if (dataGrid1.SelectedItem == null) return;

    if (dataGrid1.CurrentItem == "True" )
    {
        dataGrid1.CurrentItem = "False";
    }
    else if (dataGrid1.CurrentItem == "False")
    {
        dataGrid1.CurrentItem = "True";
    }
}

Answer 1

If you wanna know which DataGridCell is being double-clicked, you must add this to your XAML:

<DataGrid.CellStyle>
    <Style TargetType="DataGridCell">
        <EventSetter Event="MouseDoubleClick" Handler="dataGrid1_CellDoubleClick" />
    </Style>
</DataGrid.CellStyle>

And then in your code-behind, handle the event:

private void dataGrid1_CellDoubleClick(object sender, RoutedEventArgs e)
{
    var cell = sender as DataGridCell;

    // Do stuff with your cell
}

The problem is... Your DataGrid and columns are databound, so most things you do to your cell's content won't reflect in your actual data.

I say " most ", because you could, in fact, change the cell text and the value of the databound property at the same time... But it's quite dirty and doesn't really belong in the view.

private void dataGrid1_CellDoubleClick(object sender, RoutedEventArgs e)
{
    var cell = sender as DataGridCell;

    if (cell != null && cell.Content is TextBlock)
    {
        var textBlock = cell.Content as TextBlock;
        textBlock.SetCurrentValue(TextBlock.TextProperty, "put your text here");
        var binding = BindingOperations.GetBindingExpression(textBlock, TextBlock.TextProperty);
        binding.UpdateSource();
    }
}

For this to work, you have to set Mode=TwoWay on your DataGridTextColumn Bindings (though it may already be the default mode, I don't remember). Also, it won`t work with other types of columns.

BUT... As I said, this solution is dirty and you want to have that kind of logic in your viewmodel.

The easiest way to do that could be exposing a method from your viewmodel, that you could call from code-behind passing some parameters like the row's data item and the column's property name.

private void dataGrid1_CellDoubleClick(object sender, RoutedEventArgs e)
{
    var cell = sender as DataGridCell;

    if (cell != null)
    {
        (this.DataContext as MyViewModel).DoStuff(cell.DataContext, cell.Column.SortMemberPath);
    }
}