Treeview click event

Refer

https://www.aspsnippets.com/questions/148936/Get-TreeView-Selected-Node-in-SelectedIndexChanged-event-in-ASPNet/

https://www.aspsnippets.com/questions/148936/geometry dashGet-TreeView-Selected-Node-in-SelectedIndexChanged-event-in-ASPNet/

Another simple way to handle this is by using the SelectedNode.Value together with a small mapping, so you don’t end up writing too many if or switch statements as your list grows.

For example:

protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e) { var node = TreeView1.SelectedNode;

if (node == null) return;

if (node.Value == "Portugal") { Response.Redirect("Form1.aspx"); } else { // For Canada & USA just bind cities LoadCities(node.Text); } }

And just make sure your TreeView nodes are defined properly and AutoPostBack="true" is set.

This way, you keep it flexible—if later you add more countries, they’ll automatically go through the same LoadCities method without extra code.

Hi vereato,

Refer below example. Use TreeView NodeMouseClick to achieve this.

Namespaces

CS

using System.Linq;
using System.Data;

VB.Net

Imports System.Linq
Imports System.Data

Code

Form1

CS

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

    private void Form1_Load(object sender, EventArgs e)
    {
        this.CenterToScreen();
        treeView1.Nodes.Add(new TreeNode { Text = "Canada", Tag = "1" });
        treeView1.Nodes.Add(new TreeNode { Text = "USA", Tag = "2" });
        treeView1.Nodes.Add(new TreeNode { Text = "India", Tag = "3" });
    }

    private void OnNodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
    {
        TreeNode selectedNode = e.Node;
        int countryId = Convert.ToInt32(selectedNode.Tag);
        List<TreeNode> cities = this.GetCities().AsEnumerable()
            .Where(x => x.Field<int>("CountryId") == countryId)
            .Select(x => new TreeNode { Text = x["Name"].ToString(), Tag = x["Id"].ToString() })
            .ToList();
        Form2 frm2 = new Form2(cities); // Open Cities in new Form.
        frm2.ShowDialog(this);
    }

    private DataTable GetCities()
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("Id", typeof(int));
        dt.Columns.Add("Name", typeof(string));
        dt.Columns.Add("CountryId", typeof(int));
        dt.Rows.Add(1, "Toronto", 1);
        dt.Rows.Add(2, "Quebec", 1);
        dt.Rows.Add(3, "New York", 2);
        dt.Rows.Add(4, "Los Angeles", 2);
        dt.Rows.Add(5, "Mumbai", 3);
        dt.Rows.Add(6, "Bangalore", 3);
        dt.Rows.Add(7, "Delhi", 3);
        dt.Rows.Add(8, "Hyderabad", 3);
        return dt;
    }
}

VB.Net

Public Class Form1
    Public Sub New()
        InitializeComponent()
        Me.CenterToScreen()
    End Sub
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.CenterToScreen()
        treeView1.Nodes.Add(New TreeNode With {.Text = "Canada", .Tag = "1"})
        treeView1.Nodes.Add(New TreeNode With {.Text = "USA", .Tag = "2"})
        treeView1.Nodes.Add(New TreeNode With {.Text = "India", .Tag = "3"})
    End Sub

    Private Sub OnNodeMouseClick(sender As Object, e As TreeNodeMouseClickEventArgs) Handles treeView1.NodeMouseClick
        Dim selectedNode As TreeNode = e.Node
        Dim countryId As Integer = Convert.ToInt32(selectedNode.Tag)
        Dim cities As List(Of TreeNode) = Me.GetCities().AsEnumerable() _
        .Where(Function(x) x.Field(Of Integer)("CountryId") = countryId) _
        .Select(Function(x) New TreeNode With {
            .Text = x("Name").ToString(),
            .Tag = x("Id").ToString()
        }).ToList()
        Dim frm2 As Form2 = New Form2(cities) ' Open Cities in new Form.
        frm2.ShowDialog(Me)
    End Sub

    Private Function GetCities() As DataTable
        Dim dt As DataTable = New DataTable()
        dt.Columns.Add("Id", GetType(Integer))
        dt.Columns.Add("Name", GetType(String))
        dt.Columns.Add("CountryId", GetType(Integer))
        dt.Rows.Add(1, "Toronto", 1)
        dt.Rows.Add(2, "Quebec", 1)
        dt.Rows.Add(3, "New York", 2)
        dt.Rows.Add(4, "Los Angeles", 2)
        dt.Rows.Add(5, "Mumbai", 3)
        dt.Rows.Add(6, "Bangalore", 3)
        dt.Rows.Add(7, "Delhi", 3)
        dt.Rows.Add(8, "Hyderabad", 3)
        Return dt
    End Function
End Class

Form2

CS

public partial class Form2 : Form
{
    private List<TreeNode> cities;

    public Form2(List<TreeNode> nodes)
    {
        InitializeComponent();
        cities = nodes;
        this.CenterToScreen();
    }

    private void Form2_Load(object sender, EventArgs e)
    {
        treeView1.Nodes.Clear();
        treeView1.Nodes.AddRange(cities.ToArray());
    }
}

VB.Net

Public Class Form2
    Private cities As List(Of TreeNode)
    Public Sub New(nodes As List(Of TreeNode))
        InitializeComponent()
        cities = nodes
        Me.CenterToScreen()
    End Sub

    Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        treeView1.Nodes.Clear()
        treeView1.Nodes.AddRange(cities.ToArray())
    End Sub
End Class