WPF DataGrid ComboBox SelectedItem屬性設置器

Question

我正在尋找一個示例，該示例如何在WPF DataGrid的組合框中使用SelectedItem屬性，

<DataGridComboBoxColumn SelectedValueBinding="{Binding CID, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" 
                        SelectedValuePath="CID"  
                        Header="CID" 
                        Width="70">
        <DataGridComboBoxColumn.EditingElementStyle>
            <Style TargetType="ComboBox">
                <Setter Property="ItemsSource" Value="{Binding DataContext.ListCustomerCollection, 
                  RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}}"/>
                <Setter Property="DisplayMemberPath" Value="Name"/>
                <Setter Property="SelectedItem" Value="{Binding DataContext.Customer, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Window}}"></Setter> 
            </Style>
        </DataGridComboBoxColumn.EditingElementStyle>
        <DataGridComboBoxColumn.ElementStyle>
            <Style TargetType="ComboBox">
                <Setter Property="ItemsSource" Value="{Binding DataContext.ListCustomerCollection, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}}"/>
                <Setter Property="DisplayMemberPath" Value="Name"/>
                <Setter Property="HorizontalAlignment" Value="Center"></Setter>
                <Setter Property="SelectedItem" Value="{Binding DataContext.Customer, RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Window}}"></Setter>
            </Style>
        </DataGridComboBoxColumn.ElementStyle>

我綁定到（ListCustomerCollection）的DataContext是一個List對象

  List<Customer> 

所以我在ViewModel屬性中設置的屬性是

private Customer m_Customer = null;
public Customer Customer
{
    get { return m_Customer; }
    set
    {
        m_Customer = value;
        OnPropertyChanged("Customer");
    }
}

那么，如何編寫XAML以使用SelectedItem設置上述屬性？

Answer 1

如果屬性位於窗口的ViewModel中，則必須像對ItemsSource一樣獲取窗口的DataContext。

<Setter Property="SelectedItem"
        Value="{Binding DataContext.Customer,
                        RelativeSource={RelativeSource Mode=FindAncestor, 
                                                 AncestorType=Window}}"/>