WPF DataGridComboBoxColumn绑定？

Question

我正在尝试在WPF数据网格中包含一个ComboBox列。我正在尝试将此列绑定到ViewModel中的一个可观察集合，但是，在运行时，单元格仍为空。Datacontext是正确的，因为所有普通列都成功绑定。我想在UI中显示'regionShortCode‘。下面是我的xaml：

   <DataGridComboBoxColumn Header="Region" DisplayMemberPath="regionShortCode" Width="SizeToHeader">
       <DataGridComboBoxColumn.ElementStyle>
           <Style>
             <Setter Property="ComboBox.ItemsSource" Value="{Binding Path=MembershipsCollection}" />
             </Style>
                </DataGridComboBoxColumn.ElementStyle>
                 <DataGridComboBoxColumn.EditingElementStyle>
              <Style>
                 <Setter Property="ComboBox.ItemsSource" Value="{Binding Path=MembershipsCollection}" />
              </Style>
           </DataGridComboBoxColumn.EditingElementStyle>
     </DataGridComboBoxColumn>

这是我在ViewModel中声明的ObservableCollection。从构造函数中调用的方法成功填充Collection：

private ObservableCollection<tbAccountMembership> _MembershipsCollection;
    public ObservableCollection<tbAccountMembership> MembershipsCollection
    {
        get { return _MembershipsCollection; }
        set
        {
            _MembershipsCollection = value;
            OnPropertyChanged("MembershipsCollection");
        }
    }     

在运行时，我得到：

System.Windows.Data Error: 40 : BindingExpression path error: 'MembershipsCollection' property not found on 'object' ''tbAccountMembership_041E43AFC29975F12C156BA1373ACD47FC07BBE55614E5AF8AD3BBD9F090C133' (HashCode=46247020)'. BindingExpression:Path=MembershipsCollection; DataItem='tbAccountMembership_041E43AFC29975F12C156BA1373ACD47FC07BBE55614E5AF8AD3BBD9F090C133' (HashCode=46247020); target element is 'TextBlockComboBox' (Name=''); target property is 'ItemsSource' (type 'IEnumerable')

在“输出”窗口中。为什么Xaml不能解析这个绑定？谢谢

Answer 1

如果您希望从DataGrid数据绑定到视图模型中的单个集合属性，那么您的答案是为什么Xaml不能解析此绑定？是因为您没有告诉Framework在哪里查找实际的属性...您将需要使用[RelativeSource Binding]1。试着这样做：

<DataGridComboBoxColumn Header="Region" DisplayMemberPath="regionShortCode" 
    Width="SizeToHeader">
    <DataGridComboBoxColumn.ElementStyle>
        <Style>
            <Setter Property="ComboBox.ItemsSource" Value="{Binding 
                DataContext.MembershipsCollection, RelativeSource={RelativeSource 
                AncestorType={x:Type YourViewModelsPrefix:YourViewModel}}}" />
        </Style>
    </DataGridComboBoxColumn.ElementStyle>
    <DataGridComboBoxColumn.EditingElementStyle>
        <Style>
            <Setter Property="ComboBox.ItemsSource" Value="{Binding 
                DataContext.MembershipsCollection, RelativeSource={RelativeSource 
                AncestorType={x:Type YourViewsPrefix:YourView}}}" />
        </Style>
    </DataGridComboBoxColumn.EditingElementStyle>
</DataGridComboBoxColumn>

使用此Binding Path，框架将在常规DataGrid.DataContext之外查找对象中名为MembershipsCollection的属性，该属性被设置为YourView的DataContext (显然这不是实际名称) UserControl或Window。如果您的视图模型被正确设置为DataContext，那么这应该可以很好地工作。

Answer 2

您必须提供集合的确切路径，以便与combobox的itemssource绑定。为此，将您的祖先设置为您的主要控件，即窗口或用户控件

           <DataGridComboBoxColumn Header="Category"
SelectedValueBinding="{Binding category_cde}"
  SelectedValuePath="category_cde"
DisplayMemberPath="category_dsc">
                        <DataGridComboBoxColumn.ElementStyle>
                            <Style TargetType="ComboBox">
                            <Setter Property="ItemsSource" Value="{Binding Path=CATEGORIES , RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" />
                            </Style>
                        </DataGridComboBoxColumn.ElementStyle>
                        <DataGridComboBoxColumn.EditingElementStyle>
                            <Style TargetType="ComboBox">
                            <Setter Property="ItemsSource" Value="{Binding Path=CATEGORIES , RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" />
                            </Style>
                        </DataGridComboBoxColumn.EditingElementStyle>
                    </DataGridComboBoxColumn>

            </DataGrid.Columns>
        </DataGrid>

下面是我在代码中定义的类别集合，其中类别是您可以定义自己的集合的某个类

 List<Category> m_categories = new List<Category>();
    public List<Category> CATEGORIES
    {
        get { return m_categories; }
        set { m_categories = value; }
    }

Answer 3

使用DataGridComboBoxColumn的一个更简单的解决方案是在窗口类的构造函数中以编程方式设置ItemSource绑定。

<DataGrid x:Name="MembershipGridNormal" AutoGenerateColumns="False" SelectedIndex="0" ItemsSource="{Binding}">
            <DataGrid.Columns>

                <DataGridTextColumn Header="Name" Binding="{Binding Prop1}"/>
                <DataGridTextColumn Header="Value" Binding="{Binding Prop2}"/>
                <DataGridComboBoxColumn x:Name="CmbMemberShips" Header="RawValues" DisplayMemberPath="Name" />

            </DataGrid.Columns>
        </DataGrid>

在后台代码中

public Win32599087()
        {
            InitializeComponent();

            MemberShipGridNormal.DataContext = myCollection;

            Binding b = new Binding();
            b.Source =  myCollection;
            b.Path = new PropertyPath("collectionpropertyname");

            BindingOperations.SetBinding(CmbMemberships, DataGridComboBoxColumn.ItemsSourceProperty, b);
        }