如何从DataGridTemplateColumn.CellTemplate获取AutoCompleteBox的文本

Question

我正在使用WPF UI套件的DataGrid。在DataGridTemplateColumn中，我使用了AutoCompleteBox并使用值列表设置其静态资源。我想获取AutoCompleteBox的文本。开始时，我已经使用Item Object绑定了Data Grid空值，以便在AutocompleteBox中进行搜索时，选择一个值并按Enter，然后该值在MessageBox等中显示为输出。

注意：此值将进一步用于从数据库搜索项目。

问题是，按Enter键时AutoCompleteBox值显示为空。

DataGrid：

 <DataGrid Name="CartTable" Grid.Row="2"  AutoGenerateColumns="False" Margin="20,0" Height="300" GridLinesVisibility="All" CanUserAddRows="True" SelectionChanged="CartTable_SelectionChanged"  >

    <DataGrid.Columns>

        <DataGridTemplateColumn Header="Code" Width="1*">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <controls:AutoCompleteBox Text="{Binding Code, Mode=TwoWay}" ItemsSource="{StaticResource ItemList}" IsTextCompletionEnabled="True" PreviewKeyDown="AutoCompleteBox_PreviewKeyDown"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>

        <DataGridTextColumn Header="Name" Width="1*" Binding="{Binding Name}"/>

        <DataGridTextColumn Header="Description" Width="1*" Binding="{Binding Description}"/>

        <DataGridTemplateColumn Header="Quantity" Width="1*">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <controls:AutoCompleteBox Text="{Binding Quantity, Mode=TwoWay}" ItemsSource="{StaticResource ItemList}" Name="Quantity"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>

        <DataGridTextColumn Header="Unit Price" Width="1*" IsReadOnly="True"  Binding="{Binding UnitPrice}"/>

        <DataGridTextColumn Header="Sub-Total" Width="1*" IsReadOnly="True"  Binding="{Binding SubTotal}"/>

        <DataGridTemplateColumn Header="Delete" Width="1*" IsReadOnly="True">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <Button Content="Delete" Name="DelBtnGrid" Click="DelBtnGrid_Click"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>

    </DataGrid.Columns>
</DataGrid>

静态资源列表：

public class ItemCodeList : List<string>
{
    public ItemCodeList()
    {
        Items(1);
    }

    void Items(int column)
    {
        Database database = new Database();
        database.DBOpen();

        SQLiteDataReader sQLiteDataReader = database.SelectAllOrderBy(Database.TABLE_ITEMS, Database.ID_ITEMS, "DESC");
        try
        {
            this.Clear();

            while (sQLiteDataReader.Read())
            {
                string value = sQLiteDataReader.GetString(column);

                this.Add(value);
            }
            sQLiteDataReader.Close();
            database.DBClose();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        finally
        {
            if (sQLiteDataReader != null)
            {
                sQLiteDataReader.Close();
                database.DBClose();
            }
        }


    }

SaleTab：

 public SaleTab()
 {
        InitializeComponent();

        Item item = new Item()
        {=
            Code = "",
            Name = "",
            Description = "",
            Quantity = "",
            UnitPrice = "",
            SubTotal = ""
        };
}

AutoCompleteBox_PreviewKeyDown

private void AutoCompleteBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if(e.Key == Key.Enter)
    {
        AutoCompleteBox x = CartTable.Columns[0].GetCellContent(CartTable.Items[0]) as AutoCompleteBox;
        if (x != null)
        {
            MessageBox.Show(x.Text);
        } else
        {
            MessageBox.Show("null");
        }


    }
}