wpf - 绑定(bind)到 WPF 中当前数据上下文/源属性的父级/同级

Question

我们如何绑定(bind)到当前数据上下文的父级/同级(即表示当前数据上下文的源属性)？

我不是在谈论绑定(bind)到父控件的属性(这种情况涉及目标的父级而不是源的父级) - 这可以通过使用RelativeSourceMode=FindAncestor 轻松完成。

RelativeSourceMode=PreviousData 提供对绑定(bind)到数据项的前一个同级项的有限支持，但不支持绑定(bind)到父项或其他同级项。

虚拟示例:
(假设 INPC 就位)
如何将ComboBox的ItemsSource绑定(bind)到ViewModel的Departments属性？

public class Person
{
    public string Name { get; set; }
    public string Department { get; set; }
}

public class PersonViewModel
{
    public List<Person> Persons { get; set; }
    public List<string> Departments { get; set; }

    public PersonViewModel()
    {
        Departments = new List<string>();
        Departments.Add("Finance");
        Departments.Add("HR");
        Departments.Add("Marketing");
        Departments.Add("Operations");

        Persons = new List<Person>();
        Persons.Add(new Person() { Name = "First", Department = "HR" });
        Persons.Add(new Person() { Name = "Second", Department = "Marketing" });
        Persons.Add(new Person() { Name = "Third", Department = "Marketing" });
    }
}

XAML:

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication1"
        Title="MainWindow" Height="300" Width="300">
    <Grid>
        <DataGrid ItemsSource="{Binding Persons}" AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTextColumn Header="Name" Binding="{Binding Name}" />
                <DataGridTemplateColumn>
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <ComboBox ItemsSource="{Binding Departments???}"
                                      SelectedValue="{Binding Department}"/>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

Answer 1

您可以像这样访问祖先 DataContext:

<ComboBox ItemsSource="{Binding DataContext.Departments, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type DataGrid}}}"
                                  SelectedValue="{Binding Department}"/>