Important contributing factors are here to create well data table structure and binding it to tree view control. Asp.net TreeView Control.

Technology

ASP.net

SQL Server 2005

Database Implementation

Create table tbl_Tree_Hierarchy

Create Stored procedure ssp_get_hierarchy : This will give Node_ID its child information and level or depth of leaf node or branch it belongs to.The below is the result set of above stored procedure. The best use of Common table expression in SQL Server 2005 to refer recursive dataset using WITH Clause

Recursive Function

Create recursive function to traverse through hierarchical tree data structure. This functionality is developed using Asp.net 2.0 and the recursive function can be avoided using CSharp .net 3.5 using LINQ Using anonymous delegate we can compare the collection objects with some logical condition. Once the result set is filtered it can be traversed and can be added as object item to tree view control.

    public class HierarchyTrees : List <HierarchyTrees.HTree>
    { 
        public class HTree 
        {            
            private string m_NodeDescription;
            private int m_UnderParent;
            private int m_LevelDepth;
            private int m_NodeID;

            public int NodeID 
            { get {return m_NodeID;}
                set { m_NodeID=value; }
            } 

            public string NodeDescription
            {
                get { return m_NodeDescription; }
                set { m_NodeDescription = value; }
            }
            public int UnderParent
            {
                get { return m_UnderParent; }
                set { m_UnderParent = value; }
            }
            public int LevelDepth
            {
                get { return m_LevelDepth; }
                set { m_LevelDepth = value; }
            }
        } 
    }  

PopulateTreeview() function will fetch recordset from database and will populate the generic collection tree.

   private void PopulateTreeview() {    
        this.tvHierarchyView.Nodes.Clear();     
        HierarchyTrees hierarchyTrees = new HierarchyTrees();    
        HierarchyTrees.HTree objHTree=null;
        using (SqlConnection connection = new SqlConnection(@"Persist Security Info=False;Integrated Security=SSPI;database=FamilyTree;server=[Local]"))             
        {         
            connection.Open();
            using (SqlCommand command = new SqlCommand("SSP_GET_HIERARCHY", connection))     
            {             command.CommandType = System.Data.CommandType.StoredProcedure;             
                SqlDataReader reader = command.ExecuteReader(System.Data.CommandBehavior.CloseConnection);          
                while (reader.Read())             
                {              
                    objHTree=new HierarchyTrees.HTree();      
                                    
                objHTree.LevelDepth = int.Parse(reader["LEVEL_DEPTH"].ToString());
                objHTree.NodeID = int.Parse(reader["NODE_ID"].ToString());
                objHTree.UnderParent = int.Parse(reader["UNDER_PARENT"].ToString());
                objHTree.NodeDescription = reader["NODE_DESCRIPTION"].ToString();
                hierarchyTrees.Add(objHTree);
                }         
            }     
        }       
        //Iterate through Collections.
        foreach (HierarchyTrees.HTree hTree in hierarchyTrees)     
        {
            //Filter the collection HierarchyTrees based on Iteration as per object Htree Parent ID 
            HierarchyTrees.HTree parentNode = hierarchyTrees.Find(delegate(HierarchyTrees.HTree emp) { return emp.NodeID == hTree.UnderParent; });
            //If parent node has child then populate the leaf node.
            if (parentNode != null)
            {         
                foreach (TreeNode tn in tvHierarchyView.Nodes)
                {
                    //If single child then match Node ID with Parent ID
                    if (tn.Value == parentNode.NodeID.ToString())
                    {
                        tn.ChildNodes.Add(new TreeNode(hTree.NodeDescription.ToString(), hTree.NodeID.ToString()));
                    }
                    
                    //If Node has multiple child ,recursively traverse through end child or leaf node.
                    if (tn.ChildNodes.Count > 0)
                    {                    
                        foreach (TreeNode ctn in tn.ChildNodes)
                        {
                            RecursiveChild(ctn, parentNode.NodeID.ToString(), hTree);
                        }
                    }
                }                
            }
            //Else add all Node at first level 
            else
            {               
                tvHierarchyView.Nodes.Add(new TreeNode(hTree.NodeDescription, hTree.NodeID.ToString()));
            } 
            }     
        tvHierarchyView.ExpandAll(); 
    }

Create recursive function to traverse through hierarchical tree data structure. This functionality is developed using Asp.net 2.0 and the recursive function can be avoided using CSharp .net 3.5 using LINQ Using anonymous delegate we can compare the collection objects with some logical condition. Once the result set is filtered it can be traversed and can be added as object item to tree view control. Create HierarchyTrees generic collection which contains Htree objects.

 public void RecursiveChild(TreeNode tn, string searchValue, HierarchyTrees.HTree hTree)
    {
        if (tn.Value == searchValue)
        {
            tn.ChildNodes.Add(new TreeNode(hTree.NodeDescription.ToString(), hTree.NodeID.ToString()));
        }
        if (tn.ChildNodes.Count > 0)
        {
            foreach (TreeNode ctn in tn.ChildNodes)
            {
                RecursiveChild(ctn, searchValue,hTree);
            }
        }
    }
 

References

The below reference is for win form treeview control and I wrote above article to make it available for asp.net tree view control as well. The important difference between winform and asp.net treeview control is FindNode

In winform, treeview control we have tvHierarchyView.Nodes.Find where it finds a given node criteria and help us add Htree object item at given node value and hence one can use LINQ and can get rid of recursive function.

Unlike winform , asp.net treeview control exposes tvHierarchyView.FindNode(XML Address path) which is more applicable for XML data type and hence not much of help.

• Windows Tree View Control .net 3.5 :Tree view population without recusrsive function

Conclusion

Any ideas, corrections, and suggestions are most welcome.