为什么更改DataGrid ComboBox值不会更新绑定属性?
问题描述:
我有DataGridComboBoxColumn应该显示整数或文本“默认”。当我添加行时,combobox从viewmodel的绑定属性中获取正确的值,但是当我更改用户界面中的值时,该属性的集合不会被调用。我尝试了SelectedValueBinding和SelectedItemBinding。转换器的ConvertBack永远不会被调用。我不应该知道它应该被称为。为什么更改DataGrid ComboBox值不会更新绑定属性?
的事物,它们:
- 的DataGrid的SelectedItem结合
- 文本列绑定两种方式(此处省略短促)
这里是我的代码:
XAML:
<DataGrid Name="SelectionSetsGrid" CanUserAddRows="False" CanUserResizeColumns="True" CanUserSortColumns="True"
ItemsSource="{Binding SelectionSets}" AutoGenerateColumns="False"
SelectedItem="{Binding SelectedSelectionSet}">
<DataGrid.Columns>
<DataGridComboBoxColumn Header="Width" SelectedValueBinding="{Binding LineWidthIndex}">
<DataGridComboBoxColumn.ElementStyle>
<Style TargetType="ComboBox" BasedOn="{StaticResource Theme.ComboBox.Style}">
<Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.LineWidths}"/>
<Setter Property="IsReadOnly" Value="True"/>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate>
<WrapPanel>
<TextBlock Text="{Binding Converter={StaticResource IntToIntTextOrDefaultConverter}}" VerticalAlignment="Center"/>
</WrapPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</DataGridComboBoxColumn.ElementStyle>
<DataGridComboBoxColumn.EditingElementStyle>
<Style TargetType="ComboBox" BasedOn="{StaticResource Theme.ComboBox.Style}">
<Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.LineWidths}"/>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate>
<WrapPanel>
<TextBlock Text="{Binding Converter={StaticResource IntToIntTextOrDefaultConverter}}" VerticalAlignment="Center"/>
</WrapPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</DataGridComboBoxColumn.EditingElementStyle>
</DataGridComboBoxColumn>
</DataGrid.Columns>
</DataGrid>
视图模型(视图模型实现INotifyPropertyChanged和的SetValue引发的PropertyChanged):
public class SelectedObjectsViewModel : ViewModel
{
private int[] _lineWidths = { -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
public ObservableCollection<int> LineWidths { get; private set; };
private ObservableCollection<SelectionSetViewModel> _selectionSets;
public ObservableCollection<SelectionSetViewModel> SelectionSets
{
get { return _selectionSets; }
set { this.SetValue(ref _selectionSets, value); }
}
private SelectionSetViewModel _selectedSelectionSet;
public SelectionSetViewModel SelectedSelectionSet
{
get { return this._selectedSelectionSet; }
set { this.SetValue(ref _selectedSelectionSet, value); }
}
}
视图模型为DataGrid行(视图模型实现INotifyPropertyChanged和的SetValue引发的PropertyChanged):
public class SelectionSetViewModel : ViewModel
{
public SelectionSetViewModel()
{
LineWidthIndex = -1;
}
private int _lineWidthIndex;
public int LineWidthIndex
{
get { return _lineWidthIndex; }
set { SetValue(ref _lineWidthIndex, value); }
}
转换器:
public class IntToIntTextOrDefaultConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
if ((int)value == -1)
return Fusion.App.Current.Resources["StrDefault"].ToString();
return value.ToString();
}
public object ConvertBack(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
return value.Equals(true) ? parameter : Binding.DoNothing;
}
}
答
似乎在某些情况下,例如在编辑文本列并按下回车或添加新行th之后e属性WAS在更改组合框值后实际更新(set called)。所以我只是添加UpdateSourceTrigger = PropertyChanged绑定和更新源属性立即发生(而不是一些随机操作后)。请注意,从ComboBox更改焦点不足以更新源属性,所以我认为它从未更新过。
<DataGrid Name="SelectionSetsGrid" CanUserAddRows="False" CanUserResizeColumns="True" CanUserSortColumns="True"
ItemsSource="{Binding SelectionSets}" AutoGenerateColumns="False"
SelectedItem="{Binding SelectedSelectionSet}">
<DataGridComboBoxColumn Header="{StaticResource XpStrTopologyWidth}" SelectedItemBinding="{Binding LineWidthIndex, UpdateSourceTrigger=PropertyChanged}">
<DataGridComboBoxColumn.ElementStyle>
<Style TargetType="ComboBox" BasedOn="{StaticResource Theme.ComboBox.Style}">
<Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.LineWidths}"/>
<Setter Property="IsReadOnly" Value="True"/>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate>
<WrapPanel>
<TextBlock Text="{Binding Converter={StaticResource IntToIntTextOrDefaultConverter}}" VerticalAlignment="Center"/>
</WrapPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</DataGridComboBoxColumn.ElementStyle>
<DataGridComboBoxColumn.EditingElementStyle>
<Style TargetType="ComboBox" BasedOn="{StaticResource Theme.ComboBox.Style}">
<Setter Property="ItemsSource" Value="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.LineWidths}"/>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate>
<WrapPanel>
<TextBlock Text="{Binding Converter={StaticResource IntToIntTextOrDefaultConverter}}" VerticalAlignment="Center"/>
</WrapPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</DataGridComboBoxColumn.EditingElementStyle>
</DataGridComboBoxColumn>
</DataGrid.Columns>
</DataGrid>
幸运的可能是,绑定需要Mode = TwoWay? –
当然,但Web上的示例都没有DataGridComboBoxColumn绑定定义中的Mode = TwoWay。我试图用两种不同的方式,但没有奏效。此外,文本列的工作模式= TwoWay。如果你有一个想法如何正确地把它放在XAML我会很高兴:) –
由于我以前也使用复选框绑定,这里是我自己的代码的一部分:''。改了名字,但希望这有助于。 –