excel-vba CustomDocumentProperties in practice Organizing new invoice numbers

Example

Incrementing an invoice number and saving its value is a frequent task. Using CustomDocumentProperties (CDPs) is a good method to store such numbers in a relatively safe way within the same work book, but avoiding to show related cell values simply in an unprotected work sheet.

Additional hint:

Alternatively, you could enter values also in a hidden worksheet or even a so called "very hidden" worksheet (see Using xlVeryHidden Sheets. Of course, it's possible to save data also to external files (e.g. ini file, csv or any other type) or the registry.

Example content:

The example below shows

• a function NextInvoiceNo that sets and returns the next invoice number,
• a procedure DeleteInvoiceNo, that deletes the invoice CDP completely, as well as
• a procedure showAllCDPs listing the complete CDPs collection with all names. Not using VBA, you can also list them via the workbook's information: Info | Properties [DropDown:] | Advanced Properties | Custom

You can get and set the next invoice number (last no plus one) simply by calling the above mentioned function, returning a string value in order to facilitate adding prefixes. "InvoiceNo" is implicitly used as CDP name in all procedures.

Dim sNumber As String
sNumber = NextInvoiceNo ()

Example code:

Option Explicit

Sub Test()
  Dim sNumber As String
  sNumber = NextInvoiceNo()
  MsgBox "New Invoice No: " & sNumber, vbInformation, "New Invoice Number"
End Sub

Function NextInvoiceNo() As String
' Purpose: a) Set Custom Document Property (CDP) "InvoiceNo" if not yet existing
'          b) Increment CDP value and return new value as string
' Declarations
  Dim prop As Object
  Dim ret  As String
  Dim wb   As Workbook
' Set workbook and CDPs
  Set wb = ThisWorkbook
  Set prop = wb.CustomDocumentProperties

  ' -------------------------------------------------------
  ' Generate new CDP "InvoiceNo" if not yet existing
  ' -------------------------------------------------------
    If Not CDPExists("InvoiceNo") Then
    '  set temporary starting value "0"
       prop.Add "InvoiceNo", False, msoPropertyTypeString, "0"
    End If

  ' --------------------------------------------------------
  ' Increment invoice no and return function value as string
  ' --------------------------------------------------------
       ret = Format(Val(prop("InvoiceNo")) + 1, "0")
  ' a) Set CDP "InvoiceNo" = ret
       prop("InvoiceNo").value = ret
  ' b) Return function value 
       NextInvoiceNo = ret
End Function

Private Function CDPExists(sCDPName As String) As Boolean
' Purpose: return True if custom document property (CDP) exists
' Method: loop thru CustomDocumentProperties collection and check if name parameter exists
' Site: cf. http://stackoverflow.com/questions/23917977/alternatives-to-public-variables-in-vba/23918236#23918236
' vgl.: https://answers.microsoft.com/en-us/msoffice/forum/msoffice_word-mso_other/using-customdocumentproperties-with-vba/91ef15eb-b089-4c9b-a8a7-1685d073fb9f
' Declarations
  Dim cdp As Variant      ' element of CustomDocumentProperties Collection
  Dim boo As Boolean      ' boolean value showing element exists
  For Each cdp In ThisWorkbook.CustomDocumentProperties
    If LCase(cdp.Name) = LCase(sCDPName) Then
       boo = True      ' heureka
       Exit For        ' exit loop
    End If
  Next
  CDPExists = boo          ' return value to function
End Function


Sub DeleteInvoiceNo()
' Declarations
  Dim wb     As Workbook
  Dim prop   As Object
' Set workbook and CDPs
  Set wb = ThisWorkbook
  Set prop = wb.CustomDocumentProperties

' ----------------------
' Delete CDP "InvoiceNo"
' ----------------------
 If CDPExists("InvoiceNo") Then
    prop("InvoiceNo").Delete
 End If

End Sub

Sub showAllCDPs()
' Purpose: Show all CustomDocumentProperties (CDP) and values (if set)
' Declarations
  Dim wb      As Workbook
  Dim cdp     As Object

  Dim i       As Integer
  Dim maxi   As Integer
  Dim s       As String
' Set workbook and CDPs
  Set wb = ThisWorkbook
  Set cdp = wb.CustomDocumentProperties
' Loop thru CDP getting name and value
  maxi = cdp.Count
  For i = 1 To maxi
    On Error Resume Next    ' necessary in case of unset value
    s = s & Chr(i + 96) & ") " & _
            cdp(i).Name & "=" & cdp(i).value & vbCr
  Next i
' Show result string
  Debug.Print s
End Sub