Uses of TreeView Server Control with Database Table

Manoj Kalla
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TreeView.zip

TreeView control is a server side control. This controlis usable for displaying a tree view kind of structure. We can easily display hierarchy and Master/Detail type of data.

Treeview control has following types of nodes:

Root: A node that has no parent node and one or more child nodes.
Parent: A node that has a parent node and one or more child nodes.
Leaf: A node that has no child nodes.

Node is text which displays either selectable text or hyperlinks. Programmatically we can get/set the properties of TreeView. We can display a check box with node text.

Step By Step Implementation

I had used one table to implement TreeView control with Parent and Child with the example of Product Categories and Category Items.

tblProducts Table Structure

GO
/****** Object: Table [dbo].[tblProducts] Script Date: 02/19/2016 10:03:02 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[tblProducts](
[ProductID] [int] IDENTITY(1,1) NOT NULL,
[ProductName] [nvarchar](50) NOT NULL,
[ParentID] [int] NULL
) ON [PRIMARY]

Create a new ASP.NET web site EMPTY project.
Drag and Drop Treeview control on Default.aspx page
Double click on Web.Config fileand insert connection string.
1. <connectionStrings>
2. <add name="TVConnectionString" connectionString="Data Source=SAIBABA-PC\SAIBABA;Initial Catalog=MemberCDAC;Integrated Security=True" providerName="System.Data.SqlClient"/>
3. </connectionStrings>
Implementation of TreeView with help of three methods:
Fill Root Level
1. SqlConnection con = new SqlConnection(constr);
3. //Query
4. string query = "Select pcate.ProductID as ProductCategoryID ,pcate.ProductName as ProductCategoryName, (select count(*) FROM tblProducts " +
5. "WHERE parentid=pcate.ProductID) as TotItem From tblProducts pcate where pcate.ParentID Is Null";
6. SqlDataAdapter da = new SqlDataAdapter(query, con);
7. DataTable dt = new DataTable();
8. da.Fill(dt);
9. FillNodes(dt, TreeView1.Nodes);
Fill Child Level
1. SqlConnection con = new SqlConnection(constr);
2. string query = "Select pcate.ProductID as ProductCategoryID ,pcate.ProductName as ProductCategoryName, (select count(*) FROM tblProducts "+
3. " WHERE parentid=pcate.ProductID) as TotItem From tblProducts pcate where pcate.ParentID = " + parentid;
4. SqlDataAdapter da = new SqlDataAdapter(query,con);
5. DataTable dt = new DataTable();
6. da.Fill(dt);
7. FillNodes(dt, parentNode.ChildNodes);
Default.aspx code
1. <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
3. <!DOCTYPE html>
5. <html xmlns="http://www.w3.org/1999/xhtml">
7. <head runat="server">
8. <title></title>
9. </head>
11. <body>
12. <form id="form1" runat="server">
13. <div>
14. <asp:TreeView ID="TreeView1" runat="server" ExpandDepth="0" PopulateNodesFromClient="true" ShowLines="true" ShowExpandCollapse="true" OnTreeNodePopulate="TreeView1_TreeNodePopulate">
15. </asp:TreeView>
16. </div>
17. </form>
18. </body>
20. </html>
Default.aspx.cs code
1. using System;
2. using System.Collections.Generic;
3. using System.Configuration;
4. using System.Data;
5. using System.Data.SqlClient;
6. using System.Linq;
7. using System.Web;
8. using System.Web.UI;
9. using System.Web.UI.WebControls;
11. public partial class _Default: System.Web.UI.Page {
12. string constr = ConfigurationManager.ConnectionStrings["TVConnectionString"].ConnectionString;
14. protected void Page_Load(object sender, EventArgs e) {
15. if (!IsPostBack) {
16. FillRootLevel();
17. }
19. }
22. /// <summary>
23. /// Find out ProdcutCateogry having total numbers of products with query.
24. /// </summary>
25. private void FillRootLevel() {
26. SqlConnection con = new SqlConnection(constr);
28. //Query
29. string query = "Select pcate.ProductID as ProductCategoryID ,pcate.ProductName as ProductCategoryName, (select count(*) FROM tblProducts " +
30. "WHERE parentid=pcate.ProductID) as TotItem From tblProducts pcate where pcate.ParentID Is Null";
31. SqlDataAdapter da = new SqlDataAdapter(query, con);
32. DataTable dt = new DataTable();
33. da.Fill(dt);
34. FillNodes(dt, TreeView1.Nodes);
35. }
39. private void FillChildLevel(int parentid, TreeNode parentNode) {
40. SqlConnection con = new SqlConnection(constr);
41. string query = "Select pcate.ProductID as ProductCategoryID ,pcate.ProductName as ProductCategoryName, (select count(*) FROM tblProducts " +
42. " WHERE parentid=pcate.ProductID) as TotItem From tblProducts pcate where pcate.ParentID = " + parentid;
43. SqlDataAdapter da = new SqlDataAdapter(query, con);
44. DataTable dt = new DataTable();
45. da.Fill(dt);
46. FillNodes(dt, parentNode.ChildNodes);
47. }
51. /// <summary>
52. /// Fill Nodes as per DataTable
53. /// </summary>
54. /// <param name="dt"></param>
55. /// <param name="nodes"></param>
56. private void FillNodes(DataTable dt, TreeNodeCollection nodes) {
57. foreach(DataRow dr in dt.Rows) {
58. TreeNode tn = new TreeNode();
59. tn.Text = dr["ProductCategoryName"].ToString();
60. tn.Value = dr["ProductCategoryID"].ToString();
61. nodes.Add(tn);
63. //If node has child nodes, then enable on-demand populating
64. tn.PopulateOnDemand = (Convert.ToInt32(dr["TotItem"]) > 0);
65. }
66. }
69. protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e) {
70. FillChildLevel(Convert.ToInt32(e.Node.Value), e.Node);
71. }
73. }
Root level
Expanded Level : TreeView

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