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 Заполнение данных Data Bound TreeView в C#

Populate a Data Bound TreeView in .Net using C#

Visual Studio 2008 offers some out-of-the-box features that we can easily create a Treeview control in the form designer without writing much code. However if we need to (Most of time I believe we do) programmatically populate a Treeview menu, particularly if we want to populate a Treeview based on a database table, this does require some codes. In this demo, I am demonstrating how we can populate a Treeview control with database tables. The backend database is Oracle 10g R2,

I use the employee table under HR schema. It shouldn’t matter which database you are using, as long as your table or view in hierarchy structure, for instance like:

ID EMP_NAME PARENT_ID
100 Steven
101 Neena 100
102 Lex 100
103 Alexander 102
104 Bruce 103
105 David 103
106 Valli 103
107 Diana 103
108 Nancy 101

- Firstly in the form designer, we drag a Treeview control and make it dock left.
- Drag a Splitter control to the right hand side of the form and make it dock left as shown below.

- Drag a Panel control to the right hand side and make it dock top.
- Drag a Splitter control to the bottom right and make it dock top.
- Drag a third Panel to the bottom right and make it fill the rest of the screen as shown below.

- To populate the TreeViewNode, I am using a recursive function. The tag property is used to store the level of the hierarchy.


using System;
using System.Data;
using System.Windows.Forms;  
using System.Data.OracleClient;  
namespace TreeViewDemo  

 public partial class Form1 : Form  
    {  
        public Form1()  
        {  
            InitializeComponent();  
        }  
  
        DataSet dsTreeView = new DataSet();  
  
        // Populate public DataSet  
        private DataSet PopulateDataTable()  
        {  
            string connectionString = "Data Source=orcl;Persist Security Info=True; "  
                + "User ID=hr;Password=hr;Unicode=True";  
  
            string queryString = "select * from employees";  
  
            OracleConnection connection = new OracleConnection(connectionString);  
            OracleCommand command = new OracleCommand(queryString, connection);  
            OracleDataAdapter da = new OracleDataAdapter(command);  
  
            try  
            {  
                connection.Open();  
                if (!dsTreeView.Tables.Contains("emp"))  
                    dsTreeView.Tables.Add("emp");  
                da.Fill(dsTreeView, "emp");  
            }  
            catch (OracleException oex)  
            {  
                throw new Exception(oex.Message);  
            }  
            finally  
            {  
                connection.Close();  
            }  
            return dsTreeView;  
        }  

        // The level of tree  
        int intLevel = 0;  
  
        // Recursive function to populate Treeview node  
        public void FillChildren(TreeNode _Parent, int _ParentID)  
        {  
            intLevel++;  
            DataView Data = new DataView(dsTreeView.Tables["emp"]);  
            Data.RowFilter = "manager_id = " + _ParentID;  
  
            // Define the image index in the lowest level  
            if (Data.Count == 0)  
            {  
                _Parent.ImageIndex = 2;  
                _Parent.SelectedImageIndex = 2;  
            }  
  
            foreach (System.Data.DataRowView foo in Data)  
            {  
                TreeNode t = BuildNode((string)foo["last_name"]);  
                t.Tag = intLevel;  
                FillChildren(t, int.Parse(foo["employee_id"].ToString()));  
                _Parent.Nodes.Add(t);  
                System.Diagnostics.Trace.WriteLine("Added node at level " + intLevel.ToString());  
            }  
            intLevel--;  
        }  
  
        private TreeNode BuildNode(string Text)  
        {  
            return new TreeNode(Text);  
        }  
  
        private void LoadMenuTreeView()  
        {  
            PopulateDataTable();  
            DataView Data = new DataView(dsTreeView.Tables["emp"]);  
            Data.RowFilter = "manager_id is null ";  
            foreach (System.Data.DataRowView foo in Data)  
            {  
                TreeNode t = BuildNode((string)foo["last_name"]);  
                t.Tag = 0;  
                FillChildren(t, int.Parse(foo["employee_id"].ToString()));  
                this.treeView1.Nodes.Add(t);  
            }  
  
            this.treeView1.ImageList = this.imageList1;  
        }  
  
        private void Form1_Load(object sender, EventArgs e)  
        {  
            LoadMenuTreeView();  
        }  
  
        private void treeView1_AfterExpand(object sender, TreeViewEventArgs e)  
        {  
            e.Node.ImageIndex = 1;  
        }  
  
        private void treeView1_AfterCollapse(object sender, TreeViewEventArgs e)  
        {  
            e.Node.ImageIndex = 0;  
}         
    }  
}  

Run the application, we will see a data bound treeview as shown below.




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