DataGrid中的ComboBox未显示ComboBox列表项

Question

当我尝试在DataGrid中使用ComboBox时，我没有看到列表中用于填充ComboBox的任何项目。

当我使用StackPanel而不是DataGrid时，类似的实现工作。我想我在装订中遗漏了一些东西？

<Window x:Class="Demo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Demo"
        mc:Ignorable="d"
        Title="MainWindow" Height="400" Width="800">
    <Grid Margin="10">
        <DataGrid Name="dgRecords" ItemsSource="{Binding Records}" AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTemplateColumn Header="Number">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <ComboBox
                                IsEditable="True"
                                Width="120"
                                ItemsSource="{Binding Items}"
                                SelectedItem="{Binding SelectedItem}"
                                Text="{Binding NewItem, UpdateSourceTrigger=LostFocus}"/>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

namespace Demo
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        /// <summary>
        /// List which populates DataGrid.
        /// </summary>
        private List<MyRecord> _records = new List<MyRecord>();

        /// <summary>
        /// List which populates ComboBox.
        /// </summary>
        private List<string> _items = new List<string>()
        {
            "One",
            "Two",
            "Three",
            "Four",
            "Five",
        };

        private string _selectedItem;

        public class MyRecord
        {
            public string Number { get; set; }
        }

        public MainWindow()
        {
            InitializeComponent();

            this.DataContext = this;

            _records.Add(new MyRecord() { Number = "One" });
            _records.Add(new MyRecord() { Number = "Two" });
        }

        public IEnumerable Records
        {
            get { return _records; }
        }

        public IEnumerable Items
        {
            get { return _items; }
        }

        public string SelectedItem
        {
            get { return _selectedItem; }
            set
            {
                _selectedItem = value;
            }
        }

        public string NewItem
        {
            set
            {
                SelectedItem = value;

                // Set SelectedItem as Window Title.
                this.Title = "Selected: " + SelectedItem;
            }
        }
    }
}

Answer 1

添加元素绑定以指向正确的DataContext。默认情况下，它将DataContext作为MyRecord，因为它是一行datagrid。请参阅下面的代码。

 <Grid Margin="10">
        <DataGrid Name="dgRecords" ItemsSource="{Binding Records}" AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTemplateColumn Header="Number">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <ComboBox
                            IsEditable="True"
                            Width="120"
                            ItemsSource="{Binding DataContext.Items, ElementName=dgRecords}"
                            SelectedItem="{Binding SelectedItem}"
                            Text="{Binding NewItem, UpdateSourceTrigger=LostFocus}"/>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>