Excel VBA: Is there a way to reference an instance of a class stored in a dictionary? - excel

Question

I currently have instances of classes stored using the data structure presented in the image below. Each -List item is a dictionary and each -Info item is an instance of a class.
I read elsewhere that if you Set an instance variable equal to another instance, it just references the original instance. Is this correct?
I have been able to create a reference for fileInfo(1) (in the image) using the following code.
Dim prflInfo As File_Info
Set prflInfo = New File_Info
Set prflInfo = fileList.Items(0)
I have attempted to reference the branchInfo instance using the following code, but I get a Run-time error 13: Type mismatch when I attempt to do so.
Dim prbrInfo As Branch_Info
With prflInfo
Set prbrInfo = New Branch_Info
brKey = .getbrKey(0)
Set prbrInfo = .getbrItem(brKey)
End With
Edit: Included below is the code for the File_Info class. All other classes follow this basic model.
'Class Module: File_Info
'Initialise class variables
Private pfileID As Integer
Private pfilePath As String
Private pfileName As String
Private pbranchList As Scripting.Dictionary
'Declare variantcopy subroutine
Private Declare Sub VariantCopy Lib "OleAut32" (pvarDest As Any, pvargSrc As Any)
Private Sub Class_Initialize()
Set pbranchList = New Scripting.Dictionary
End Sub
Public Property Let fileID(pfileIDi As Variant)
pfileID = pfileIDi
End Property
Public Property Get fileID() As Variant
fileID = pfileID
End Property
Public Property Let filePath(pfilePathi As Variant)
pfilePath = pfilePathi
End Property
Public Property Get filePath() As Variant
filePath = pfilePath
End Property
Public Property Let fileName(pfileNamei As Variant)
pfileName = pfileNamei
End Property
Public Property Get fileName() As Variant
fileName = pfileName
End Property
Public Sub addbrConn(branch As Branch_Info)
pbranchList.Add branch.branchID, branch.brConn
Debug.Print "addbrConn ID: " & branch.branchID
End Sub
Public Sub addBranch(branch As Branch_Info)
pbranchList.Add branch.branchID, branch
Debug.Print pbranchList.Count
End Sub
Public Function countbrList()
countbrList = pbranchList.Count
End Function
Public Function getbrKey(Key As Variant)
getbrKey = pbranchList.Keys(Key)
End Function
Public Function getbrItem(Key As Variant)
getbrItem = GetByRefVariant(pbranchList.Items(Key))
End Function
Public Sub dpbrList()
With pbranchList
Debug.Print pbranchList.Count
For k = 1 To pbranchList.Count
Debug.Print .Keys(k - 1), .Items(k - 1)
Next k
End With
End Sub
Public Sub updbrList(branch As Branch_Info)
Dim branchID As String
branchID = branch.branchID
If pbranchList.exists(branchID) Then
pbranchList.Remove (branchID)
pbranchList.Add branchID, branch
Debug.Print "Complete: " & branchID & " added."
Else
Debug.Print "Error: " & branchID & "does not exist."
End If
End Sub
Private Function GetByRefVariant(ByRef var As Variant) As Variant
VariantCopy GetByRefVariant, var
End Function
Is there a way to reference the branchInfo class, to make it easier to extract the data within it?
Thanks!
Eeshwar

Answer 1

I do things differently in that I iterate through the keys list using a For ... each loop rather than referring to an item number. Here is a snippet that works using two levels.
You can ignore the lines where the property values are written to an array, but they were part of the original code.
cf.Dependents is a dictionary of cDependents within the cFamily object
'Declarations in Main Module
Dim dF As Dictionary, cF As cFamily, cD As cDependents
Dim I As Long, J As Long
Dim V As Variant, W As Variant
...
For Each V In dF
I = I + 1
Set cF = dF(V)
With cF
vRes(I, 1) = .FirstName
vRes(I, 2) = .LastName
vRes(I, 3) = .Birthdate
J = 2
For Each W In .Dependents
J = J + 2
Set cD = .Dependents(W)
With cD
vRes(I, J) = .Relation
vRes(I, J + 1) = .DepName
End With
Next W
End With
Next V
Note that in the sequence, as you show in your question:
set Obj = new Obj
set Obj = myClass(0)
the first line is unnecessary.

Answer 2

IMO it is possible to use simple VBA.Collection, here example for the FileList and BranchList. In this example List classes have Items and Info classes have reference to List where List is wrapper for a VBA.Collection. HTH
For more reading have a look e.g. here.
FileList Class
Option Explicit
Private m_fileInfoCollection As FileInfoCollection
Private Sub Class_Initialize()
Set m_fileInfoCollection = New FileInfoCollection
End Sub
Public Property Get Items() As FileInfoCollection
Set Items = m_fileInfoCollection
End Property
FileInfo Class
Option Explicit
Private m_branchList As BranchList
Private m_fileID As Integer
Private Sub Class_Initialize()
Set m_branchList = New BranchList
End Sub
Public Property Get FileID() As Integer
FileID = m_fileID
End Property
Public Property Let FileID(ByVal vNewValue As Integer)
m_fileID = vNewValue
End Property
Public Property Get BranchList() As BranchList
Set BranchList = m_branchList
End Property
FileInfoCollection Class
Option Explicit
Private m_collection As VBA.Collection
Private Sub Class_Initialize()
Set m_collection = New VBA.Collection
End Sub
Public Sub Add(ByVal newItem As FileInfo)
m_collection.Add newItem, CStr(newItem.FileID)
End Sub
Public Function ItemByKey(ByVal key As String) As FileInfo
Set ItemByKey = m_collection(key)
End Function
Public Function ItemByIndex(ByVal index As Long) As FileInfo
Set ItemByIndex = m_collection(index)
End Function
Public Function Count() As Long
Count = m_collection.Count
End Function
BranchList Class
Option Explicit
Private m_branchInfoCollection As BranchInfoCollection
Private Sub Class_Initialize()
Set m_branchInfoCollection = New BranchInfoCollection
End Sub
Public Property Get Items() As BranchInfoCollection
Set Items = m_branchInfoCollection
End Property
BranchInfo Class
Option Explicit
Private m_branchID As Integer
Public Property Get branchID() As Integer
branchID = m_branchID
End Property
Public Property Let branchID(ByVal vNewValue As Integer)
m_branchID = vNewValue
End Property
BranchInfoCollection Class
Option Explicit
Private m_collection As VBA.Collection
Private Sub Class_Initialize()
Set m_collection = New VBA.Collection
End Sub
Public Sub Add(ByVal newItem As BranchInfo)
m_collection.Add newItem, CStr(newItem.branchID)
End Sub
Public Function ItemByKey(ByVal key As String) As BranchInfo
Set ItemByKey = m_collection(key)
End Function
Public Function ItemByIndex(ByVal index As Long) As BranchInfo
Set ItemByIndex = m_collection(index)
End Function
Public Function Count() As Long
Count = m_collection.Count
End Function
Standard Module
Option Explicit
Sub Demo()
' Fill
Dim bi As BranchInfo
Set bi = New BranchInfo
bi.branchID = 111
Dim fi As FileInfo
Set fi = New FileInfo
fi.FileID = 222
fi.BranchList.Items.Add bi
Dim fl As FileList
Set fl = New FileList
fl.Items.Add fi
' Get
Dim fi1 As FileInfo
Set fi1 = fl.Items.ItemByIndex(1)
Dim bi1 As BranchInfo
Set bi1 = fi1.BranchList.Items(1)
End Sub