WinForm 中ListBox显示三级分类，分类列表出现DataRowView的问题

[BevisLiao]

1.运行窗体，点击右上角的生成数据。
2.查出第一级分类，listbox中的数据全部是DataRowView,点击弹出的小窗体后，数据正常显示。此时还会弹出小窗体。如第一张图
3.点击小窗体的确定，二级分类显示正常。

正常的效果：点击生成数据，显示一级分类。选择一级分类的某个选项，在第二个listbox中显示二级分类。

选择二级分类后，显示对应的二级分类下的三级分类（如果能实现三级分类更好，现在的三级分类出现同样的问题）

using MySql.Data.MySqlClient;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SpecTools
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            //读取当前访问的数据库连接字符串
            //string dbConnStr= txtConfigStr.Text;
            txtConfigStr.Text = "此处为数据库连接字符串";
            
            MysqlHeper.DBConnectionString = txtConfigStr.Text;
        }

        private void BtnReadData_Click(object sender, EventArgs e)
        {
            //显示一级分类
            string firstLevelSql = "SELECT categoryid,categoryname FROM wlerp.ali_category where topcategoryid=-1";
            DataTable dt = MysqlHeper.ExecuteDataSet(CommandType.Text, firstLevelSql, null).Tables[0];

            if (dt.Rows.Count > 0)
            {
                this.FirstLevelCategory.DataSource = dt;
                this.FirstLevelCategory.DisplayMember = "categoryname";
                this.FirstLevelCategory.ValueMember = "categoryid";
            }
            else
            {
                MessageBox.Show("没有数据！");
            }
        }


        private void FirstLevelCategory_SelectedValueChanged(object sender, EventArgs e)
        {
            //获取当前的一级分类id
            string topcategoryid = this.FirstLevelCategory.SelectedValue.ToString();

            //根据选中的一级分类id查询对应的二级分类
            string secondCateSql = "SELECT * FROM wlerp.ali_category where topcategoryid!=-1 and secondcategoryid=-1 and topcategoryid=?topcategoryid";

            MySqlParameter paramer = new MySqlParameter("?topcategoryid", topcategoryid);
            DataTable dt = MysqlHeper.ExecuteDataSet(CommandType.Text, secondCateSql, paramer).Tables[0];
            if (dt.Rows.Count > 0)
            {
                this.SecondLevelCategory.DataSource = dt;
                this.SecondLevelCategory.DisplayMember = "categoryname";
                this.SecondLevelCategory.ValueMember = "categoryid";
            }
            else
            {
                MessageBox.Show("没有数据！");
            }
        }

        private void SecondLevelCategory_SelectedValueChanged(object sender, EventArgs e)
        {
            ////获取当前的一级分类id
            //string secondcategoryid = this.SecondLevelCategory.SelectedValue.ToString();

            ////根据选中的一级分类id查询对应的二级分类
            //string thirdCateSql = "SELECT * FROM wlerp.ali_category where topcategoryid!=-1 and secondcategoryid !=-1 and secondcategoryid=?secondcategoryid";

            //MySqlParameter paramer = new MySqlParameter("?secondcategoryid", secondcategoryid);
            //DataTable dt = MysqlHeper.ExecuteDataSet(CommandType.Text, thirdCateSql, paramer).Tables[0];
            //if (dt.Rows.Count > 0)
            //{
            //    this.ThirdLevelCategory.DataSource = dt;
            //    this.ThirdLevelCategory.DisplayMember = "categoryname";
            //    this.ThirdLevelCategory.ValueMember = "categoryid";
            //}
            //else
            //{
            //    MessageBox.Show("没有数据！");
            //}
        }
    }
}

[Justin-Liu]

太长了没看，debug能解决吧，在事件里面获取选中的item取值进行查询绑定下一级数据源控件