VBA Code is recursive calls allowed? (1 Viewer)

Option Compare Database
Option Explicit

Private mTVW As clsTreeview

Private mNodeQueryName As String
Private mRootParentID As Variant
Private mRecordSet As DAO.Recordset
Private mNodeIDfield As String
Private mParentIDfield As String
Private mNodeTextField As String
Private mNodeLevelField As String

'To use this module for loading records either by individual level or recursively create queries as follows.
'Each query needs the following fields
'NodeID: This should be a concatenated field of the PK with the NodeLevel
'NodeText: This should be a concatenated field for the caption of what is visible
'NodeLevel: This should identify what level of the tree only needed for non recursive calls. Can be the name of the table
'ParentID: This is the concatenated field of the the ParentID foreign key and the ParentNodeLevel
'Example

'SELECT [NodeLevel] & "_" & [Order ID] AS NodeID, "Order: " & [Order ID] & "   Order Date: " & [Order Date] AS NodeText, "Order" AS NodeLevel,
'Employee" & "_" & [orders].[employee id] AS ParentID,
'FROM Orders


Public Sub InitializLoader(Treeview As clsTreeview)
  On Error GoTo ErrHandler
  Set mTVW = Treeview
  Exit Sub
ErrHandler:
      MsgBox ("Error: " & Err.Number _
            & " " & Err.Description _
            & " " & Err.Source)
   Resume Next
End Sub
Public Sub AddRecursiveRecords(NodeQueryName As String, RootParentID As String)
   'Parent and Child IDs are numeric see the instructions on concatenation to make them strings
   Dim strCriteria As String
   Dim bk As String
   Dim NodeID As String
   Dim NodeText As String
   Dim CurrentNode As clsNode
   Dim NodeLevel As String
   
   Set Me.NodeRecordset = CurrentDb.OpenRecordset(NodeQueryName, dbOpenDynaset)
   strCriteria = "ParentID = '" & RootParentID & "'"
   Me.NodeRecordset.FindFirst strCriteria
   If Me.NodeRecordset.NoMatch Then
    MsgBox "There is no record with a Parent ID of " & RootParentID
   End If
   Do Until Me.NodeRecordset.NoMatch
    NodeID = Me.NodeRecordset.Fields("NodeID")
    NodeText = Me.NodeRecordset.Fields("NodeText")
    NodeLevel = Me.NodeRecordset.Fields("NodeLevel")
    Set CurrentNode = Me.Treeview.AddRoot(NodeID, NodeText)
    With CurrentNode
       .Tag = NodeLevel
       .Bold = True
      .Expanded = False
    End With
    bk = Me.NodeRecordset.Bookmark
    Call AddRecursiveBranch(NodeID, NodeLevel, CurrentNode)
    'ensure you return back to where you were since the bookmark is moving in recursive calls
    Me.NodeRecordset.Bookmark = bk
    Me.NodeRecordset.FindNext strCriteria
  Loop
  Me.Treeview.Refresh
End Sub
Private Sub AddRecursiveBranch(ByVal ParentID As Variant, ByVal NodeLevel, ParentNode As clsNode)

  On Error GoTo errLable
  Dim strCriteria As String
  Dim bk As String
  Dim NodeID As String
  Dim NodeText As String
  Dim CurrentNode As clsNode
 
  strCriteria = "ParentID = '" & ParentID & "'"
  Me.NodeRecordset.FindFirst strCriteria
  
  Do Until Me.NodeRecordset.NoMatch
    NodeID = Me.NodeRecordset.Fields("NodeID")
    NodeText = Me.NodeRecordset.Fields("NodeText")
    NodeLevel = Me.NodeRecordset.Fields("NodeLevel")
    Set CurrentNode = ParentNode.AddChild(NodeID, NodeText)
    With CurrentNode
       .Tag = NodeLevel
       .Bold = False
      .Expanded = False
    End With
 
   bk = Me.NodeRecordset.Bookmark
   'Recursive call
   Call AddRecursiveBranch(NodeID, NodeLevel, CurrentNode)
   Me.NodeRecordset.Bookmark = bk
   Me.NodeRecordset.FindNext strCriteria
  Loop
 Exit Sub
errLable:
  MsgBox Err.Number & " " & Err.Description & " In addBranch"
  If MsgBox("Do you want to exit the loop?", vbYesNo, "Error In Loop") = vbYes Then
     Exit Sub
   Else
     Resume Next
   End If
End Sub

Public Sub AddRecordsByLevel(NodeQueryName As String, NodeLevel As String, Optional IsRootLevel = False)
  'Ensure query has these fields see instructions
  'Node level needs to match the query see instructions
  On Error GoTo ErrHandler
  Dim NodeID As String
  Dim NodeText As String
   Dim CurrentNode As clsNode
  Dim ParentID As String
  Dim ParentNode As clsNode
  Dim Key As String
  Set Me.NodeRecordset = CurrentDb.OpenRecordset(NodeQueryName, dbOpenDynaset)
  Do While Not Me.NodeRecordset.EOF
    
    NodeID = Me.NodeRecordset.Fields("NodeID")
    NodeText = Me.NodeRecordset.Fields("NodeText")
    NodeLevel = Me.NodeRecordset.Fields("NodeLevel")
    If IsRootLevel Then
      Set CurrentNode = Me.Treeview.AddRoot(NodeID, NodeText)
      With CurrentNode
       .Tag = NodeLevel
       .Bold = True
      .Expanded = False
     End With
    Else
      ParentID = Me.NodeRecordset.Fields("ParentID")
      Set ParentNode = Me.Treeview.Nodes(ParentID)
      Set CurrentNode = ParentNode.AddChild(NodeID, NodeText)
      With CurrentNode
       .Tag = NodeLevel
       '.Bold = True
       .Expanded = False
      End With
    End If
    Me.NodeRecordset.MoveNext
  Loop
  
  'create the node controls and display the tree
   Me.Treeview.Refresh

  Exit Sub
ErrHandler:
      MsgBox ("Error: " & Err.Number _
            & " " & Err.Description _
            & " " & Err.Source)
   If MsgBox("Do you want to exit the loop?", vbYesNo, "Error In Loop") = vbYes Then
     Exit Sub
   Else
     Resume Next
   End If
End Sub
Public Property Get NodeRecordset() As DAO.Recordset
  Set NodeRecordset = mRecordSet
End Property

Public Property Set NodeRecordset(NewNodeRecordSet As DAO.Recordset)
  Set mRecordSet = NewNodeRecordSet
End Property

Public Property Get Treeview() As clsTreeview
  Set Treeview = mTVW
End Property