从LINQ到SQL类填充的WPF组合框显示类型而不是名称

Question

我有一个带组合框的WPF窗口。应该从SQL表中的列填充组合框的内容。我在models文件夹中创建了一个LINQ To SQL数据上下文类，并将ComboBox的ItemsSource设置为由数据上下文生成的类（Customers）。但是当我运行程序时，组合框的内容是类型的它拉的物品..

代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using eTouchLV.GatekeeperUI.Models;

namespace eTouchLV.GatekeeperUI
{
    public partial class MainWindow : Window
    {
        SQLDataClassDataContext dc = new SQLDataClassDataContext(Properties.Settings.Default.GatekeeperDBConnectionString);

        public MainWindow()
        {
            InitializeComponent();
            AssignDataToComponents();
        }

        private void AssignDataToComponents()
        {
            this.CheckDBIsValid();
            comboCustomers.ItemsSource = dc.Customers;
        }

        private void CheckDBIsValid()
        {
            if (!dc.DatabaseExists())
            {
                MessageBox.Show("Program started on the machine but can't seem to find the database...", "Error connecting to DB on SQL server.");
            }
        }
    }
}

程序：