Question

I have to build a tree using the following data which comes from a DB:

ID          Name     ManagerID
180002      john     180001
180003      Michel   180002
180005      smith    180003

john
 |_Michel
    |_ smith

Specifically, I need to make an ASP.NET TreeView control. The depth of the TreeView is not fixed.

Answer 1

You didn’t specify whether you’re using C# or VB, but the approach is the same either way.

You start by creating a TreeNode for every top-level individual (the ones without ManagerIDs, or with a special ManagerID code that indicates top-level).

Then, recursively, for every individual that reports to the current manager, create a new TreeNode and add it as a child for the current manager. Find everyone who reports to him, and apply this function to them. Stop when no one reports to the current person.

So, assuming you have a DataSet with the details of this table, you’d do something like this (VB example):

Sub PopulateTreeNode(
  CurrentNode As TreeNode,
  CurrentManagerID As String,
  Table As DataTable
) As TreeNode
  For Each Row As DataRow In _ 
  DataTable.Select("ManagerID = '" & CurrentManagerID & "'")
    Dim CurrentUser As String = Row("ID").ToString()
    Dim Node As New TreeNode(CurrentUser)
    PopulateTreeNode(Node, CurrentUser, Table)
    CurrentNode.Nodes.Add(Node)
  Next
End Sub