c# - Wpf 主从 ListView 绑定(bind)

Question

我有一个这个模型(它不是实际代码，为了清楚起见，我省略了 INotifyPropertyChanged 实现)。

  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 View 模型

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

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

在 View 中，我有两个 ListView ，一个显示组件，另一个绑定(bind)到第一个显示所选组件项目的 ListView 。后一个 ListView 应该有一个用于任何项目的组合框，以便更改 lookupitem，但我无法绑定(bind)它。

这是xaml

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

和后者

  <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>

我无法填充组合框。 Wpf 给我错误

  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')

Answer 1

尝试将您的 ViewModel 添加为 DataContext，例如。对于 Window，像这样:

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

或在代码隐藏中:

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

然后在 DataTemplate 中这样写:

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