省市数据递归加载到TreeView

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient; namespace 省市数据递归加载到TreeView
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
} private void button1_Click(object sender, EventArgs e)
{
////1.把所有的省份及直辖市加载到TreeView的根节点上。
//List<Area> listProvince = GetSubItemByParentId(0);
//foreach (Area item in listProvince)
//{
// treeView1.Nodes.Add(item.AreaName);
//} //递归将省市加载到TreeView中
LoadDataToTree(treeView1.Nodes, );
}
//递归加载到TreeView
private void LoadDataToTree(TreeNodeCollection treeNodeCollection, int pid)
{
//1.根据指定的pid获取该城市下的子城市
List<Area> listCity = GetSubItemByParentId(pid); //2.遍历将获取到的数据绑定到treeNodeCollection节点集合中
foreach (var item in listCity)
{
//返回刚刚增加的这个节点
TreeNode node = treeNodeCollection.Add(item.AreaName);
LoadDataToTree(node.Nodes, item.Areaid);
}
} //先封装一个方法,根据父Id查询下面的所有子项
private List<Area> GetSubItemByParentId(int pid)
{
List<Area> list = new List<Area>();
string sql = "select * from TblArea where areaPid=@pid";
using (SqlDataReader reader = SqlHelper.ExecuteReader(sql, new SqlParameter("@pid", pid)))
{
if (reader.HasRows)
{
while (reader.Read())
{
Area model = new Area();
model.Areaid = reader.GetInt32();
model.AreaName = reader.GetString();
model.AreaPid = reader.GetInt32();
list.Add(model); /////不要直接在这里递归,一定要先把数据获取到一个集合中,然后再递归
/////否则会打开很多个连接。
}
}
} return list;
}
}
public class Area
{
public int Areaid { get; set; }
public string AreaName { get; set; }
public int AreaPid { get; set; }
}
}
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