How to Bind a TreeView in Asp.Net?

In this example, I am showing you how to bind a treeview. Here, I am having a table in database where we store Modules and their sub-modules having parent-child like relationship.
Step-1: Add a TreeView to your .aspx Page.

    <asp:TreeView ID="ModuleTreeView" runat="server" ShowLines="true"

   PopulateNodesFromClient="false" BackColor="#99CCFF" style="width:100%"         

   ShowExpandCollapse="false">

    </asp:TreeView>

Step-2: Add a table named "Module" to your database which will store all modules and sub-modules.

Step-3: Insert some values into your table. 

All those modules which do not have any parent modules, their ParentModuleID is set to '0(Zero)'.

Step-4: Add these following code behind methods to the page.

SqlConnection con = new SqlConnection("----Your Connection String----");

    SqlCommand com;

    protected void Page_Load(object sender, EventArgs e)

    {

        ModuleTreeView.ExpandAll();

        FillTreeView();

    }

    //----- Get all the module details from database -----//

    public DataTable GetModuleDetails()

    {

        com = new SqlCommand("select ModuleID,ModuleName,ParentModuleID from Module", con);

        SqlDataAdapter da = new SqlDataAdapter(com);

        DataTable dt = new DataTable();

        da.Fill(dt);

        return dt;

    }

    //----Method to fill the treeview-----//

    public void FillTreeView()

    {

        DataTable Modules = new DataTable();

        Modules = GetModuleDetails();

        ModuleTreeView.Nodes.Clear();

        PopulateTreeNode(Modules, null, 0);

    }

    //----- Method to bind the treeview nodes as per the moduleID and ParentModuleID-----//

    private void PopulateTreeNode(DataTable ModuleList, TreeNode parent, int parentID)

    {

        TreeNodeCollection baseNodes;

        TreeNode node;

        if (parent == null)

        {

            baseNodes = ModuleTreeView.Nodes;

        }

        else

        {

            baseNodes = parent.ChildNodes;

        }

        foreach (DataRow dtRow in ModuleList.Rows)

        {

            if (int.Parse(dtRow["ParentModuleID"].ToString()) == parentID)

            {

                node = new TreeNode();

                node.Text = dtRow["ModuleName"].ToString();

                node.Value = dtRow["ModuleID"].ToString();

                node.SelectAction = TreeNodeSelectAction.Select;

                baseNodes.Add(node);

                PopulateTreeNode(ModuleList, node, int.Parse(dtRow["ModuleID"].ToString()));

            }

        }

        ModuleTreeView.ExpandAll();

    }

Now we are done and we can find the result by debugging the page.

The Final Output:

Regards,

Prajanuranjan....