ms Access: Looping through array of DAO recordsets results in element always being missing - arrays

Question

I have some vba code that 'attempts' to loop through an array of DAO recordsets. When running the loop, I get a runtime error 'Oject required' at rst.MoveFirst. It seems that rst is not properly initialized but I'm not sure how to fix it. Maybe looping through an array of recordsets isnt even possible in this way I have never tried it before. The code runs from a custom class module. There is a bunch more code in the module but most of the important stuff I post below. A couple things I tried:
Set rst to a new recordset instance manually:
Set rst = New DAO.Recordset
Declaring the array outside the loop:
Set recordsets = Array(rstRechenwerte, rstZwischenwerte, rstZutaten)
' Loop through each recordset and insert data into Excel file
For Each rst In recordsets
Setting rst to an open recordset right before rst.MoveFirst:
For Each rst In Array(rstRechenwerte, rstZwischenwerte, rstZutaten)
Set rst = rst.OpenRecordset()
rst.MoveFirst
The three recordsets in the array are properly initialized, set and are not Nothing. I had previously written the code for each of the three recordsets seperately and it works that way. I am aware that I need to change the variable name XLColumn, but thats not really an issue atm. Its probably something bassic but I couldn't figure it out for a while now so I thought I'd just ask.
I am using the following libraries for which references are properly set:
Visual Basic for Applications
Microsoft Access 16.0 Object Library
OLE Automation
Microsoft Office 16.0 Access database engine Object
Library
Microsoft Excel 16.0 Object Library
Microsoft Office 16.0 Object Library
My version of Access:
Microsoft® Access® für Microsoft 365 MSO (Version 2301 Build 16.0.16026.20002) 32 Bit
The code:
Option Compare Database
Option Explicit
Dim xlApp As Object
Dim xlWB As Object
Dim xlSheet As Object
Dim rsRes As DAO.Recordset 'rs of temp table (Output)
Dim rsZwi As DAO.Recordset 'rs of temp table (Zwischenwerte)
Dim rsRec As DAO.Recordset 'rs clone of subform Rechenwerte
Dim Recordset As Recordset
Dim rstRechenwerte As DAO.Recordset 'rs of tblRechenwerte
Dim rstZwischenwerte As DAO.Recordset 'rs of tblZwischenwerte
Dim rstZutaten As DAO.Recordset 'rs of tblZutaten
Dim RezeptID As Integer 'Current form active RezeptID
Dim RechengruppeID As Integer 'Current Form active RechengruppeID
Dim xlColumn As String 'Excel Column of Zutaten
Dim xlLastRow As Long 'Excel last row number after insertion
Dim xlColumn2 As String 'Excel Column one to the right of Zutaten
Dim k As Integer
Dim Export As Boolean 'Export the Excel File
Dim ExclExportPath As String 'Export location as string
Sub Calculate()
'***************************************************************************
'Purpose: Calculate a recipe based on Rechenwerte,
'save them temporarily and display them on a form.
'Inputs: None
'***************************************************************************
'***********************************************************************
' Preparations
'***********************************************************************
'Disable user input
Call mdlMiscFunctions.DisableKeyboardMouse(True)
'Clear temporary data tables for Results and Zwischenwerte
If Not rsRes.EOF Then Call ClearTableOnClose("tblTempResults")
If Not rsZwi.EOF Then Call ClearTableOnClose("tblTempZwischenwerte")
'Prevent prompt to save changes to excel
xlApp.DisplayAlerts = False
xlApp.Visible = False
'***********************************************************************
' Insert Data into Excel File
'***********************************************************************
Dim rst As DAO.Recordset
Dim xlCell As String
Dim xlFormula As String
Dim xlColumn As String
' Loop through each recordset and insert data into Excel file
For Each rst In Array(rstRechenwerte, rstZwischenwerte, rstZutaten)
rst.MoveFirst
If Not rst.EOF Then
Do Until rst.EOF
xlCell = rst!xlCell
xlSheet.Range(xlCell).Value = rst.Fields(1)
If rst.Fields.Count > 2 Then
xlFormula = rst!xlFormula
xlSheet.Range(xlCell).Offset(0, 1).Formula = xlFormula
xlSheet.Range(xlCell).Offset(0, 1).Value = xlSheet.Range(xlCell).Offset(0, 1).Value
Else
xlSheet.Range(xlCell).Offset(0, 1).Value = rst.Fields(2)
End If
rst.MoveNext
Loop
Else
Select Case rst.Name
Case "rstRechenwerte"
MsgBox "Error: Keine Rechenwerte vorhanden!", vbCritical
Case "rstZwischenwerte"
MsgBox "Error: Keine Zwischenwerte vorhanden!", vbCritical
Case "rstZutaten"
MsgBox "Error: Keine Zutaten vorhanden!", vbCritical
End Select
End If
Next rst
Class initialization is the following:
Private Sub Class_Initialize()
'***************************************************************************
'Purpose: Sub for initializing class variables
'Inputs: None
'***************************************************************************
'Values for variables 1 (Neccesary for recordsets)
RezeptID = Forms.frmCalcBatch.RezeptID 'RezeptID on current form
RechengruppeID = Forms.frmCalcBatch.RechengruppeID 'Rechengruppe on Current Form
'Initialize Objects
Set xlApp = CreateObject("Excel.Application")
Set xlWB = xlApp.Workbooks.Add
Set xlSheet = xlWB.Sheets("Tabelle1") 'Set xlSheet to the first sheet in the workbook
Set rsRes = CurrentDb.OpenRecordset("tblTempResults", dbOpenDynaset)
Set rsZwi = CurrentDb.OpenRecordset("tblTempZwischenwerte", dbOpenDynaset)
Set rsRec = Forms.frmCalcBatch.frmSubRechenwerteBox.Form.Recordset.Clone 'rs clone of Rechenwerte subform
Set rstRechenwerte = CurrentDb.OpenRecordset("SELECT Rechenwert, WertBezeichnung, XLCell FROM tblRechenwerte WHERE RechengruppeID = " & RechengruppeID)
Set rstZwischenwerte = CurrentDb.OpenRecordset("SELECT ZWBezeichnung, XLFormula, XLCell FROM tblZwischenwerte WHERE RezeptID = " & RezeptID)
Set rstZutaten = CurrentDb.OpenRecordset("SELECT Zutat, XLFormula, XLCell FROM tblZutaten WHERE RezeptID = " & RezeptID)
'Values for Variables 2 (recordsets neccesary for variables)
xlColumn2 = Split(rstZutaten!xlCell, "1")(0) 'extract excel column denominator for Zutaten
xlColumn2 = Chr(Asc(xlColumn2) + 1) 'Move one column to the right using Asc (A->B etc.)
'Settings:
If Forms.frmCalcBatch.cbExport = True Then
Export = True
ExclExportPath = GetExportPath
Else
Export = False
ExclExportPath = ""
End If
End Sub

Answer 1

You cannot New up a DAO.Recordset, the code will not even compile.
To loop through an array of recordsets, each recordset must initialized before it is added to the array.
For example:
Dim r1 As DAO.Recordset, r2 As DAO.Recordset, r3 As DAO.Recordset
Set r1 = CurrentDb().OpenRecordset("YourTableOrQueryName")
Set r2 = CurrentDb().OpenRecordset("YourTableOrQueryName")
Set r3 = CurrentDb().OpenRecordset("YourTableOrQueryName")
Put the recordsets now in the array.
Dim arr As Variant
arr = Array(r1, r2, r3)
To loop, you need to use a For loop and either access the recordset from the array directly, or declare another recordset variable to hold the iterating recordset.
Through an iterator variable:
Dim r As DAO.Recordset, i As Integer
For i = LBound(arr) To UBound(arr)
Set r = arr(i)
If Not r.EOF Then
r.MoveFirst
Debug.Print r.RecordCount
End If
Next i
Access it directly from the array:
For i = LBound(arr) To UBound(arr)
If Not arr(i).EOF Then
arr(i).MoveFirst
Debug.Print arr(i).RecordCount
End If
Next i
Though I fail to see why you need to have 3 recordsets in memory at the same time. Personally, I would offload the work that needs to be done in the loop to a separate function and pass the recordset as parameter. The function itself would return a success/failed status, so you can take the appropriate action based on the result.
Another approach would be to store the source names in the array, and create the recordset on demand during the loop.
Hope this helps.