Wpf主从表绑定ListView

Question

我有这个模型（这不是实际代码，我省略了INotifyPropertyChanged实现以使它更清晰易懂）。

  public class Project
  {
       public ObservableCollection<Component> Components { get; set; }
  }

  public class Component
  {
       public ObservableCollection<Item> Items { get; set; }
  }

  public class Item 
  {
       public LookupItem LookupItem { get; set; }
  }

这是ViewModel

  public class ViewModel
  {
        public Project Project { get; set; }
        public Components { get { return Project.Components; } }

        public ObservableCollection<LookupItem> LookupItems { get; set; }
  }

在我的视图中，我有两个列表视图，一个显示组件，另一个绑定到第一个，显示所选组件的项目。后面的列表视图应该为任何项目提供下拉框，以便更改查找项，但我无法进行绑定。

以下是XAML代码：

   <ListView x:Name="list" ItemsSource="{Binding Components}">
       ......
   </LIstView>

而后者

  <ListView  ItemsSource="{Binding Items}" DataContext="{Binding SelectedItem, ElementName=list}">
....
<GridViewColumn Width="140">
    <GridViewColumnHeader Tag="Publisher" Content="Item" />
    <GridViewColumn.CellTemplate>
        <DataTemplate>
            <Grid HorizontalAlignment="Stretch">
                <ComboBox SelectedItem="{Binding Path=Item}" ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:ViewModel}}, Path=LookupItems, Mode=TwoWay }" DisplayMemberPath="Name" />
            </Grid>
        </DataTemplate>
    </GridViewColumn.CellTemplate>
</GridViewColumn>

我无法使下拉框填充。WPF给我错误提示。

  System.Windows.Data Error: 4 : Cannot find source for binding with 
  reference 'RelativeSource FindAncestor, AncestorType='Projectname.ViewModels.ViewModel', AncestorLevel='1''. BindingExpression:Path=LookupItems; DataItem=null; target element is 'ComboBox' (Name=''); target property is 'ItemsSource' (type 'IEnumerable')

- Stefano.net

Answer 1

尝试将你的ViewModel作为DataContext添加，例如对于Window，可以像这样：

<Window.DataContext>
    <local:ViewModel />
</Window.DataContext>

或者在代码后端:

var viewModel = new ViewModel();
this.DataContext = viewModel;

在DataTemplate中编写如下内容：

<DataTemplate>
    <Grid HorizontalAlignment="Stretch">
        <ComboBox ItemsSource="{Binding Path=DataContext.LookupItems, 
                                        RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}},
                                        Mode=TwoWay}" ... />
    </Grid>
</DataTemplate>

- Anatoliy Nikolaev