sqltreeviewsourcedemo.aspx.cs

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using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
using System.Web.UI.HtmlControls;

public partial class SQLTreeViewSourceDemo : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
    {
        if (e.Node.ChildNodes.Count == 0)
        {
            if (e.Node.Depth == 0)
            {
                GetCategoriesList(e.Node);
            }
            else if(e.Node.Depth == 1)
            {
                GetProductsList(e.Node);
            }
        }
    }

    void GetCategoriesList(TreeNode node)
    {
        SqlCommand sqlQuery = new SqlCommand("Select CategoryName, CategoryID From Categories");
        DataSet ds;
        ds = DBOperation(sqlQuery);
        if (ds.Tables.Count > 0)
        {
            foreach (DataRow row in ds.Tables[0].Rows)
            {
                TreeNode NewNode = new TreeNode(row["CategoryName"].ToString(),row["CategoryID"].ToString());
                NewNode.PopulateOnDemand = true;
                NewNode.SelectAction = TreeNodeSelectAction.Expand;
                node.ChildNodes.Add(NewNode);
            }
        }
    }

    void GetProductsList(TreeNode node)
    {
        SqlCommand sqlQuery = new SqlCommand();
        sqlQuery.CommandText = "Select ProductName From Products Where CategoryID = @categoryid";
        sqlQuery.Parameters.Add("@categoryid", SqlDbType.Int).Value = node.Value;
        DataSet ds = DBOperation(sqlQuery);
        if (ds.Tables.Count > 0)
        {
            foreach (DataRow row in ds.Tables[0].Rows)
            {
                TreeNode NewNode = new TreeNode(row["ProductName"].ToString());
                NewNode.PopulateOnDemand = false;
                NewNode.SelectAction = TreeNodeSelectAction.None;
                node.ChildNodes.Add(NewNode);
            }
        }
    }

    private DataSet DBOperation(SqlCommand sqlQuery)
    {
        string connectionString = ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;
        SqlConnection DBConnection = new SqlConnection(connectionString);
        SqlDataAdapter dbAdapter = new SqlDataAdapter();
        dbAdapter.SelectCommand = sqlQuery;
        sqlQuery.Connection = DBConnection;
        DataSet ds = new DataSet();
        try
        {
            dbAdapter.Fill(ds);
        }
        catch
        {

        }
        return ds;
    }
}