Terminate method not called in Access 2021 - vba

Anyone else finding that their Terminate() method in Access isn't being called?
Here's my code for my cBusyPointer class with the comments removed for brevity:
Option Compare Database ' Use database order for string comparisons
Option Explicit ' Declare EVERYTHING!
Option Base 1 ' Arrays start at 1
Public Sub show()
DoCmd.hourGlass True
End Sub
Private Sub Class_Terminate()
DoCmd.hourGlass False
End Sub
Typical usage is:
Sub doTehThings()
Dim hourGlass As New cBusyPointer
hourGlass.show()
' Do all teh things
End Sub
In previous versions, this class would restore the hourglass whenever the object went out of scope and was destroyed.
I even tried to manually destroy my hourglass object:
Sub doTehThings()
Dim hourGlass As cBusyPointer
Set hourGlass = New cBusyPointer
hourGlass.show()
' Do all teh things
Set hourGlass = Nothing
End Sub
The only way to fix this is to add a hide() method and call that.
Has anyone else encountered this problem?

I cannot replicate the issue. The Terminate() method is called upon reaching the Set hourGlass = Nothing.
A couple of points:
Dim hourGlass As New cBusyPointer
This will create a new instance every time you call the hourGlass variable even to set it to Nothing. See the answer in the link below for additional info:
What's the difference between Dim As New vs Dim / Set
You should always use Dim/Set when working with objects.
hourGlass.show()
This does not even compile in VBA. Subs do not accept parentheses even when arguments are being expected, unless they are preceded with the Call keyword.
Lastly, the cleanest way to reference an object is to access it using the With statement which ensures the object is terminated when the End With statement is reached.
With New cBusyPointer
.show
End With

Related

Proper release of COM objects in code

I have just started to migrate some code from VBA to VB.Net. So I am an absolute beginner in VB.Net – but I want to do things right. Maybe some of my questions are stupid but I guess that is because I am a beginner.
So as a first exercise I have developed my first piece of code (see below). Now I thought I have to release ALL COM objects again. Two of them throw errors already while writing the code. And others throw errors at runtime.
But the funny thing is: Weather I release the rest of the COM objects or not (by making the relevant not yet commented lines of Marshal.Release to comments as well – then all lines starting with Marshal.Release are comment lines) the behavior of the code is absolutely the same to my eyes.
Can anybody tell me where I can see/find the difference?
The internet tells me that there must be a difference?
But I guess I just don’t understand (till now).
Besides this many more questions are in my head:
Does every “Dim” statement create a COM Object - that has to be released later on?
If not how do I detect whether a COM object has been created or not? Which “Dim” statements create COM object and which don't?
In this example: Dim ActiveWindow As Object = Nothing Try ActiveWindow = Me.HostApplication.ActiveWindow() Catch End Try
Is
Marshal.ReleaseComObject(ActiveWindow)
identical to
Marshal.ReleaseComObject(Me.HostApplication.ActiveWindow())?
According to this:
http://www.codeproject.com/Tips/235230/Proper-Way-of-Releasing-COM-Objects-in-NET
Would it not be better to release each "level" separately like this:
Marshal.ReleaseComObject(Me.HostApplication.ActiveWindow())
Marshal.ReleaseComObject(Me.HostApplication)
Marshal.ReleaseComObject(Me)
Overall: Am I trying to release too much? Or is it correct / good practie?
And what does "GC.Collect()" and "… = Null" have to do with all this? I have not used it at all. Should I better use it? Why? ( "... = Null" I have seen here:
http://www.codeproject.com/Tips/162691/Proper-Way-of-Releasing-COM-Objects-in-NET)
Why do I get “ShapeCount was not declared …” - Error if I try to do “Marshal.ReleaseComObject(ShapeCount)”? The same with “ShRange”. I think these are COM objects as well?!?
How do I notice when is the best time to release the COM object again? When I process/debug my code step by step with F11 will it be possible for me to determine the best (soonest) point of release? So far I have no “feeling” about when the COM object is not needed anymore and I can release it.
Any help and explanations very welcome.
Here is the code I am talking about:
Imports System.Runtime.InteropServices
Imports System.ComponentModel
Imports System.Windows.Forms
Imports AddinExpress.MSO
Imports PowerPoint = Microsoft.Office.Interop.PowerPoint
'Add-in Express Add-in Module
<GuidAttribute("D75C609E-7632-400F-8A6F-6A6E6E744E75"),
ProgIdAttribute("MyAddin8.AddinModule")> _
Public Class AddinModule
Inherits AddinExpress.MSO.ADXAddinModule
#Region " Add-in Express automatic code "
[…]
#End Region
Public Shared Shadows ReadOnly Property CurrentInstance() As AddinModule
Get
Return CType(AddinExpress.MSO.ADXAddinModule.CurrentInstance, AddinModule)
End Get
End Property
Public ReadOnly Property PowerPointApp() As PowerPoint._Application
Get
Return CType(HostApplication, PowerPoint._Application)
End Get
End Property
Private Sub AdxRibbonButton2_OnClick(sender As Object, control As IRibbonControl, pressed As Boolean) Handles AdxRibbonButton2.OnClick
MsgBox(GetInfoString2())
End Sub
Friend Function GetInfoString2() As String
Dim ActiveWindow As Object = Nothing
Try
ActiveWindow = Me.HostApplication.ActiveWindow()
Catch
End Try
Dim Result As String = "No document window found!"
If Not ActiveWindow Is Nothing Then
Select Case Me.HostType
Case ADXOfficeHostApp.ohaPowerPoint
Dim Selection As PowerPoint.Selection =
CType(ActiveWindow, PowerPoint.DocumentWindow).Selection
Dim WindowViewType As PowerPoint.PpViewType = PowerPoint.PpViewType.ppViewNormal
Dim SlideRange As PowerPoint.SlideRange = Selection.SlideRange
Dim SlideCountString = SlideRange.Count.ToString()
If WindowViewType = 9 And SlideCountString < 2 Then
Dim ShRange As PowerPoint.ShapeRange = Nothing
Try
ShRange = Selection.ShapeRange
Catch
End Try
If Not ShRange Is Nothing Then
Dim ShapeCount = ShRange.Count.ToString()
Result = "You have " + ShapeCount _
+ " shapes selected."
Else
Result = "You have 0 shapes selected."
End If
End If
'Marshal.ReleaseComObject(ShapeCount)
'Marshal.ReleaseComObject(ShRange)
'Marshal.ReleaseComObject(WindowViewType)
'Marshal.ReleaseComObject(SlideCountString)
Marshal.ReleaseComObject(SlideRange)
Marshal.ReleaseComObject(Selection)
Case Else
Result = AddinName + " doesn't support " + HostName
End Select
'Marshal.ReleaseComObject(Me.HostType)
'Marshal.ReleaseComObject(Result)
Marshal.ReleaseComObject(Me.HostApplication.ActiveWindow())
Marshal.ReleaseComObject(Me.HostApplication)
'Marshal.ReleaseComObject(Me)
End If
Return Result
End Function
End Class
The ReleaseComObject method of the Marshal class decrements the reference count of the specified Runtime Callable Wrapper (RCW) associated with the specified COM object, it doesn't release an object. It comes from the COM nature.
Typically you need to release every object returned from the Office (PowerPoint in your case) object model. Exceptions are objects passed to event handlers as parameters.
You may read more about that and find answers to your multiple questions in the When to release COM objects in Office add-ins developed in .NET article.
FinalReleaseComObject calls ReleaseComObject til it returns 0 which means release of COM object. Calling them in reverse order as in Excel objects(Application, Workbook, Worksheet) is the proper way to dispose of COM objects that are related.
Exception Condition
ArgumentException
o is not a valid COM object.
ArgumentNullException
o is null.

VBA event raise only once (intermittent)

Context
My VBA code often replace worksheets inside the Workbook. Therefore I can't use code directly in the worksheet module as it would be eventually deleted in the process.
I use a user-defined class to handle my events (strongly inspired from Chip Pearson's withevents article)
Public WithEvents ws As Worksheet
Private Sub ws_Activate()
If ActiveSheet.Name = FREEBOM_SHEET_NAME Then
Call FREEBOM_Worksheet_Activate_Handler
End If 'ActiveSheet.Name = FREEBOM_SHEET_NAME
End Sub
Private Sub ws_Change(ByVal Target As Range)
'MsgBox Target.Parent.Name
If Target.Parent.Name = FREEBOM_SHEET_NAME Then
Call FREEBOM_Worksheet_Change_Handler(Target)
End If 'Target.Parent.Name = FREEBOM_SHEET_NAME
If Target.Parent.Name = BOM_SHEET_NAME Then
Call BOM_Worksheet_Change_Handler(Target)
End If 'Target.Parent.Name = BOM_SHEET_NAME
End Sub
The class is being instantiated when the workbook is opened.
Private Sub Workbook_Open()
Dim WSObj_FreeBOM As FreeBOM_CWorkSheetEventHandler
Dim WSObj_BOM As FreeBOM_CWorkSheetEventHandler
If Freebom_EventCollection Is Nothing Then
Set Freebom_EventCollection = New Collection
End If
Set WSObj_FreeBOM = New FreeBOM_CWorkSheetEventHandler
Set WSObj_FreeBOM.ws = Sheets(FREEBOM_SHEET_NAME)
Set WSObj_BOM = New FreeBOM_CWorkSheetEventHandler
Set WSObj_BOM.ws = Sheets(BOM_SHEET_NAME)
Freebom_EventCollection.Add Item:=WSObj_FreeBOM, Key:=Sheets(FREEBOM_SHEET_NAME).Name
Freebom_EventCollection.Add Item:=WSObj_BOM, Key:=Sheets(BOM_SHEET_NAME).Name
End Sub
During my reading on the subject, I saw that linking your object to a public collection (the declaraiton is in another module (an ordinary module - not a Worksheet module and not a Class module). : Public Freebom_EventCollection As Collection would keep my instance alive even if the execution leaves the scope of the current initianlization function.
Problem Description
In most scenario, I will get only one ws_change event being raised. After that, the sheet behave as if there is no event handler in my code. Nothing is being raised, not just the worksheet events.
I have look at Application.EnableEvents but it is always set to True after the first run.
Also, when I use the build in Private Sub Worksheet_Change(ByVal Target As Range) function it worked well.
To me it is probably linked to the fact that I use a class and it is not staying alive after the first run. But then, I do not know what I am doing wrong.
Thank you in advance for you time and help in this matter.
you need to declare a module level Public instance of the Collection in an ordinary module (not a Worksheet module and not a Class module). You may as well put the code to manage the collection there as well and simply have calls from the event handlers of the worksheet modules. You may need to re-initialise the collection whenever you delete a sheet as this will probably trigger a re-compile and reset your project, which will terminate your objects.
Once you have the collection in the standard module, you can monitor its life cycle by adding a watch (SHIFT-F9 in VBE). Then you can keep track of exactly what is going on.

Excel VBA - QueryTable AfterRefresh function not being called after Refresh completes

I am developing an Excel (2010+) Application using VBA and have run into an issue where the AfterRefresh event function is not being invoked once the query finishes executing.
I have not been able to find many decent resources or documentation for how to have this event function triggered in a Class Module. I decided to use the Class Module design route instead of putting the event handlers in the worksheet after receiving a response to an earlier question about QueryTables (found here Excel VBA AfterRefresh).
Here is the code for my Class Module called CQtEvents
Option Explicit
Private WithEvents mQryTble As Excel.QueryTable
Private msOldSql As String
' Properties
Public Property Set QryTble(ByVal QryTable As QueryTable): Set mQryTble = QryTable:
End Property
Public Property Get QryTble() As QueryTable: Set QryTble = mQryTble:
End Property
Public Property Let OldSql(ByVal sOldSql As String): msOldSql = sOldSql:
End Property
Public Property Get OldSql() As String: OldSql = msOldSql:
End Property
Private Sub Class_Initialize()
MsgBox "CQtEvents init"
End Sub
' Resets the query sql to the original unmodified sql statement
' This method is invoked when the Refresh thread finishes executing
Private Sub mQryTble_AfterRefresh(ByVal Success As Boolean)
' Problem is here
' This function is never called :( Even if the query successfully runs
Me.QryTble.CommandText = Me.OldSql
End Sub
Here is a quick snapshot of the code the creates an instance of this class, finds a relevant QueryTable, then calls Refresh
Option Explicit
Sub RefreshDataQuery()
'Dependencies: Microsoft Scripting Runtime (Tools->References) for Dictionary (HashTable) object
'From MGLOBALS
cacheSheetName = "Cache"
Set cacheSheet = Worksheets(cacheSheetName)
Dim querySheet As Worksheet
Dim interface As Worksheet
Dim classQtEvents As CQtEvents
Set querySheet = Worksheets("QTable")
Set interface = Worksheets("Interface")
Set classQtEvents = New CQtEvents
Dim qt As QueryTable
Dim qtDict As New Scripting.Dictionary
Set qtDict = UtilFunctions.CollectAllQueryTablesToDict
Set qt = qtDict.Item("Query from fred2")
''' Building SQL Query String '''
Dim sqlQueryString As String
sqlQueryString = qt.CommandText
Set classQtEvents.QryTble = qt
classQtEvents.OldSql = sqlQueryString ' Cache the original query string
QueryBuilder.BuildSQLQueryStringFromInterface interface, sqlQueryString
' Test message
MsgBox sqlQueryString
qt.CommandText = sqlQueryString
If Not qt Is Nothing Then
qt.Refresh
Else
' ... Error handling code here...
End If
''' CLEAN UP '''
' Free the dictionary
Set qtDict = Nothing
End Sub
Also here is a screenshot of the Module structure http://imgur.com/8fUcfLV
My first thought on what might be the issue was passing the QueryTable by value. I am not the most experienced VBA developer, but I reasoned this would create a copy and be calling the event on an unrelated table. However, this was not the case and passing by Reference did not fix the problem either.
Also the query is confirmed to run successfully as the data is correctly showing up and being refreshed.
EDIT
I added the BeforeRefresh event function to CQtEvents class Module and confirmed this function is called once Refresh is called
Private Sub mQryTble_BeforeRefresh(Cancel As Boolean)
MsgBox "Start of BeforeRefresh"
End Sub
How might I alter this code get my QueryTable from the QTableModule's RefreshDataQuery() Sub routine to have the AfterRefresh function invoked when the query is successfully ran?
How to catch the AfterRefresh event of QueryTable?
Explanation: in your situation, before event was fired you lost reference of your QueryTable by setting it to nothing when you made cleaning or procedure ended.
General solution: you must be sure that your code is still running and/or you need to keep any references to your QueryTable.
1st solution. When calling QT.Refresh method set the parameter to false in this way:
qt.Refresh false
which will stop further code execution until your qt is refreshed. But I don't consider this solution to be the best one.
2nd solution. Make your classQtEvents variable public and after RefreshDataQuery sub is finished check the status with some other code.
in you CQtEvents class module add the following public variable:
Public Refreshed As Boolean
in your BeforeRefresh event add this:
Refreshed = False
in your AfterRefresh event add this line of code:
Refreshed = True
Make your classQtEvents variable declaration public. Put this before Sub RefreshDataQuery()
Public classQtEvents as CQtEvents
but remove appropriate declaration from within your sub.
Now, even your sub is finished you will be able to check status of refreshment by checking .Refreshed property. You could do it in Immediate or within other Sub. This should work for Immediate:
Debug.Print classQtEvents.Refreshed
3rd solution. (a bit similar to 1st one) Follow steps 1 to 3 from 2nd solution. After you call qt.Refresh method you could add this loop which will stop further code execution until qt is refreshed:
'your code
If Not qt Is Nothing Then
qt.Refresh
Else
' ... Error handling code here...
End If
'checking
Do Until classQtEvents.Refreshed
DoEvents
Loop
Final remark. I hope I didn't mixed up qt variable with classQtEvents variable. I didn't tried and tested any solution using your variables but wrote all above with referenced to code I use.
A github repo that demonstrates the minimum code needed to get this working can be found here.
As mentioned, if your event handler isn't in scope, or your QueryTable reference is lost, you won't catch the event. The key factors to ensuring you catch the event are:
Declare a global variable of your event-handling class module's type outside of any subroutines/methods, at the top of a file (I chose the ThisWorkbook file).
Add a Workbook_Open event handler and instantiate that variable there, so that it is available immediately and will remain in scope (since it's global).
At that point, or at any downstream point when you have a QueryTable you're interested in, pass that QueryTable to the global instance to wire up its events.
(It took me a couple tries to figure this out myself, when someone pointed me in this direction as an answer to this question.)

Error capturing onreadystatechange of MSXML2.DOMDocument in VBA

I am getting an error trying to arrange asynchronous loading and parsing of an XML document in VBA using a wrapper class.
Following the ideas described in this msdn article and this tutorial which have worked perfectly for asynchronous handling of MSXML2.XMLHTTP40.send method I attempted to do a similar thing for DOMDocument.loadXML.
Here is the code from the wrapper class DOMMonitor
Private domDoc As MSXML2.DOMDocument
Public Event onXmlLoadComplete(d As MSXML2.DOMDocument)
Public Sub loadXML(XmlFilePath As String)
Set domDoc = CreateObject("MSXML2.DOMDocument")
domDoc.async = True
domDoc.onreadystatechange = Me ' error occurs here
domDoc.Load XmlFilePath
End Sub
Public Sub onLoadComplete()
If domDoc.readyState = "4" Then
RaiseEvent onXmlLoadComplete(domDoc)
End If
End Sub
I have made onLoadComplete the default method by setting VB_UserMemId = 0, so it is supposed to be invoked when domDoc fires onreadystatechange .
However when I invoke loadXML
Dim dm As DomMonitor
Set dm = New DomMonitor
dm.loadXML txtXMLData
i get the following runtime error in this line:
domDoc.onreadystatechange = Me
This object cannot sink the 'onreadystatechange' event. An error occurred marshalling the object's IDispatch interface
What am I doing wrong and is there a good workaround here?
Thanks in advance.
P.S. The reason I am republishing the event is that I do not necessarily want use the default method of the final subscriber for this purpose. However, as things stand now I do not even get to that stage.
The way I read that msdn article is that to assign a wrapper class to the readystatechange, the object has to be either an IXMLHTTPRequest or an IServerXMLHTTPRequest object (bullet 3). Since your object is a DOMDocument, readystatechange doesn't accept an object.
However, you can instantiate a DOMDocument WithEvents (bullet 2), making the other way redundant, I guess. I don't have an xml file large enough to test, but I think this should work. I assume that if the class loses scope, all bets are off, so I made it a global variable.
In a standard module
Public clsDOMMonitor As CDOMMonitor
Sub test()
Set clsDOMMonitor = New CDOMMonitor
clsDOMMonitor.loadXML "C:\Users\dkusleika\Downloads\wurfl-2.3.xml"
End Sub
In CDOMMonitor class
Private WithEvents mDoc As MSXML2.DOMDocument
Private Sub mDoc_onreadystatechange()
If mDoc.readyState = 4 Then
MsgBox "second"
End If
End Sub
Public Sub loadXML(XmlFilePath As String)
Set mDoc = New MSXML2.DOMDocument
mDoc.async = True
mDoc.Load XmlFilePath
MsgBox "first"
End Sub
I assume that setting async to True is all that is needed for this to work properly. My 100k xml file is probably done so fast that that the event never gives up control. But if you had a sufficiently large xml file, I think you would get "first" before "second".
Change the class' Instancing property from Private to PublicNotCreatable when late binding, whilst also applying the tweak which you have mentioned.
Use the above example when early binding (as in your case).

VBA [classes] - how to access a previously instanciated instance of a class in another sub

I've created the instance "Lassie" of the class "Dog" within a particular sub in my program. I have also given it some useful properties, such as Lassie.Age = 7 and Lassie.HeelCapability = False.
Now I would like to access another sub and change the Lassie.HeelCapability to True.
How do I go about defining the instance "Lassie" within this new sub so it can be worked with?
All the code I have come accross goes like this:
Dim Lassie As classDog
Set Lassie = New classDog
Essentially what I am looking for is a way to import the existing instance "Lassie" into another sub, without using the keyword "New" and thereby creating a new "Lassie" (without all the properties previously given).
The errormessages I have been receiving tell me either "object required" or "object variable or with block variable not set".
Surely there is a way to do this.
Thanks in advance.
You will need to pass 'Lassie' as a parameter to your other sub.
public sub DeclareSub()
Dim Lassie as classDog
Lassie = new classDog
OtherSub Lassie
end sub
public sub OtherSub(ByRef dog as classDog)
end sub
The variable 'dog' in the subroutine 'OtherSub' refers to the same object instance as the variable 'Lassie' from 'DeclareSub'.
Pass the object in ByRef to your new Subroutine.
Sub ChangeHeel(ByRef olassie As classDog)
'change the object here, and it will be changed in the calling sub
olassie.HeelCapability = True
End Sub