In general, I've been looking for how to properly check that an object is assigned.
In this particular case, it is the parent property.
I have forms that sometimes have a parent, and have slightly different behavior on resizing.
But this code
If (Not Parent Is Nothing) Then
MsgBox "Is Nothing says Parent is Assigned"
Else
MsgBox "Is Nothing says Parent is not Assigned"
End If
If (IsObject(Parent)) Then
MsgBox "IsObject says Parent is Assigned"
Else
MsgBox "IsObject says Parent is not Assigned"
End If
both work fine if there is a parent and both give an error if not.
Run-time error '2452' The expression you entered has an invalid
reference to the Parent property.
Is the only hope to catch the error and handle it there?
If you know the name of form(s) that form could be installed on as subform, can either loop through Forms collection and test if one equals "parent" form name (see #Gustav answer) or use IsLoaded method to test if a specific form is open in Forms collection (If CurrentProject.AllForms("DataBituminous").IsLoaded Then). Form when used as subform will not be in Forms collection.
If you don't want to hard-code parent form name, then use error handling code to deal with missing parent. Example found at https://www.access-programmers.co.uk/forums/threads/how-to-check-if-a-form-has-a-parent-form.157642/
Private Property Get HasParent As Boolean
On error GoTo handler
HasParent = Typename(Me.Parent.Name) = "String"
Exit Property
handler:
End Property
You can check, if the form is opened as a main form:
If IsFormOpen(Me.Name) Then
MsgBox Me.Name & " has no parent."
Else
MsgBox Me.Name & " has a parent."
End If
' Checks if a form by name is open in the current database.
' Returns True if it does, False if not.
'
' 2011-10-10, Cactus Data ApS, Gustav Brock
'
Public Function IsFormOpen(ByVal FormName As String) As Boolean
Dim Form As Form
For Each Form In Forms
If Form.Name = FormName Then
Exit For
End If
Next
IsFormOpen = Not Form Is Nothing
End Function
Related
I have a bit of an oddball problem. I use a routine to check focus; and ... it stopped working. I have no idea how or why.
The routine basically checks to see if the active control is the one you're checking, and if so, returns true (so we can handle the cases where it's not).
However...it recently started returning false all the time (we didn't change anything, we only noticed when some field auditing started returning weird values). Even when the control is focused, and if there's no other controls on the form, or only one form open, and the form clearly has focus.
Does anyone have any ideas how or why this might be? It's confounding me. As you can see, I've got a test field, where we're running an init in it...and the values clearly match, name, values, every field compared, and it still doesn't return true.
What am I doing wrong?
Edit: forgot to add the code.
The whole thing as-is:
' I call it from here:
' Inside form, any control, say `PurchaseCostBox`
Private Sub PurchaseCostBox_AfterUpdate()
' Check if the focus is had
If VerifyFocus(Me.PurchaseCostBox) Then
' Save more field info.
Debug.Print Me.PurchaseCostBox.SelStart
Debug.Print Me.PurchaseCostBox.SelLen
Debug.Print Me.PurchaseCostBox.Value
Else
' Do limited stuff
Debug.Print Me.PurchaseCostBox.Value
End if
End Sub
Public Function VerifyFocus(ByRef ctlWithFocus As Control) As Boolean
Dim FrmParent As Form
Dim ctlCurrentFocus As Control
On Error Resume Next
' Determine parent form for control
' Verify focus of parent form
Set FrmParent = Screen.ActiveForm
' Verify focus of control on form
Set ctlCurrentFocus = FrmParent.ActiveControl
If Not ctlCurrentFocus Is ctlWithFocus Then
ctlWithFocus.SetFocus
DoEvents
End If
' Even adding the below line does not return true:
ctlWithFocus.SetFocus
' Return true if the control currently has the focus
VerifyFocus = FrmParent.ActiveControl Is ctlWithFocus
' Discard any errors
Err.Clear
End Function
I've also had it try this:
Public Function VerifyFocus(ByRef ctlWithFocus As Control) As Boolean
On Error Resume Next
' Return true if the control currently has the focus
VerifyFocus = Screen.ActiveControl Is ctlWithFocus
' Discard any errors
Err.Clear
End Function
Neither work any more...and I'm floundering.
Well, this turned out to be something utterly unexpected, and totally unrelated to the focus.
Turns out, one of the ways I call this is by getting a control's parent, by using Control.Properties.Parent.Form. While this DOES return the correct form, it also makes the above VerifyFocus routine never return true, ever (even when it's not being used). I don't know why. I really, at this point, don't care. But I'm going to leave it here for others to find.
Refactoring my GetTopForm routines allowed me to get the focus.
In MS Access 2016, let's say I have 2 forms: frmMain and frmBaby.
I have embedded frmBaby as a subform on frmMain. I have embedded on frmBaby a control (let's say it's a textbox, but it could be any control) named tbxInput.
On frmMain, since frmBaby is a "control" on frmMain, I have given that control the traditional name of subfrmBaby.
Now, in VBA, an event on subfrmBaby passes the tbxInput control ByRef (as Me.tbxInput) to a function that is meant to return the .Left property of the parent of the control passed ByRef. That is, I need the function to determine the .Left property for the location of subfrmBaby on frmMain. (The function is more complicated than this, but for the sake of keeping this question let's just say the function is returning the .Left property value because the .Left value is what I need to perform the function.)
Let's say the function is: Public Function fncLocation(ByRef whtControl As Variant) as Long
(I use Variant so that null values can be passed.)
Here is the code that I expected to return the .Left value of the parent (i.e., subfrmBaby) of whtControl: lngLeft = whtControl.Parent.Left
However, that gives me an error of: "Application or object-defined error"
When I use the immediate window to check things out I find that whtControl.Parent.Name is "frmBaby" and not "subfrmBaby" which makes it problematic to reference the subform on frmMain since I cannot figure out how to get the actual name given to the control on frmMain from the object passed to the function and so I cannot reference the subform by name either.
Questions:
How can I get the .Left value for the parent of the control passed to this function?
How can I get the actual name assigned to the subform control on frmMain? In this case, I need the name of "subfrmBaby" rather than "frmBaby."
Thanks in advance for ideas.
You can do this by iterating the controls on the main form, assuming whtControl is the form object of the subform (if it's a textbox, it's whtControl.Parent.Parent and If c.Form Is whtControl.Parent Then)
Dim mainForm As Form
Set mainForm = whtControl.Parent
Dim c As Access.Control
Dim subformControl As Access.Control
For Each c In mainForm.Controls
If TypeOf c Is SubForm Then
If c.Form Is whtControl Then
Set subformControl = c
Exit For
End If
End If
Next
If Not subformControl Is Nothing Then
Debug.Print subformControl.Left
End If
Note that iterating controls comes at a performance penalty, but this code should still take milliseconds, not seconds. Also, since we test reference equality, it works even if the same subform is present multiple times on the parent form.
I just had this issue, and I think I solved it! Thanks to Eric A's answer above to get me started. I tweaked it and built on it for my use. In my case, I needed to save the "full" address of a control to build and facilitate a control log (used to log both user actions for auditing and to allow for users to "undo" an action). I have several duplicated subforms in several sub-form controls, and a few sub-sub forms (each displaying differently filtered and sorted data), so I couldn't rely on simply knowing the subform's name, I also needed the subform control name. This also leverages others' work (as noted in the code notes with some tweaks to allow easier re-use for us. I've posted it here, hopefully it will help someone else. I know I've used SO a lot.
How we use it:
On a form, after logging an action, we record the control's ID info, which calls a function to get the toppost form (this is used in conjunction with afterUpdate event so we refresh the main form and subform). We also use the HWND to validate some other items elsewhere, and to grab a form if we don't have the initial form reference. If you use this and modify it, please point back to here and give comments.
Specific Function Code to get Control "address" and get control from address
' Posted on StackOverflow 2022 February 18 in response to Question:
' https://stackoverflow.com/q/66425195/16107370
' Link to specific answer: https://stackoverflow.com/a/71176443/16107370
' Use is granted for reuse, modification, and sharing with others
' so long as reference to the original source is maintained and you
' help lift others up as others have done those who helped with this concept
' and code.
Private Function GetControlAddress(ByRef ControlTarget As Object, _
ByRef ParentForm As Access.Form) As String
' Used in concert with building a form ID, this allows reflection back to the specific
' subform control and containing subform.
Dim ControlSeek As Access.Control
If TypeOf ControlTarget Is Form Then
' You need to dig through the whole list to get the specific controls for proper reflection down.
For Each ControlSeek In ParentForm.Controls
If ControlSeek Is ControlTarget Then
GetControlAddress = ParentForm.Name & FormIDHWNDSep & ParentForm.Hwnd & FormIDHWNDSep & ControlTarget.Name & FormIDFormSep
Exit For
ElseIf TypeOf ControlSeek Is SubForm Then
If ControlSeek.Form Is ControlTarget Then
GetControlAddress = ParentForm.Name & FormIDHWNDSep & ParentForm.Hwnd & FormIDHWNDSep & ControlSeek.Name & FormIDFormSep
End If
End If
Next ControlSeek
Else
' If you're not looking for a form, then you can skip the slow step of running through all controls.
GetControlAddress = ParentForm.Name & FormIDHWNDSep & ParentForm.Hwnd & FormIDHWNDSep & ControlTarget.Name & FormIDFormSep
End If
End Function
Public Function GetControlByAddress(ByRef StartingForm As Access.Form, ByRef strControlAddress As String) As Access.Control
' Given a control address and a starting form, this will return that control's form.
Dim ControlTarget As Access.Control
Dim TargetForm As Access.Form ' This is a reference to the hosting control
'Dim ControlSeek As
Dim FormIDArr() As String
Dim FormInfo() As String
Dim ControlDepth As Long
Dim CurrentDepth As Long
If strControlAddress = vbNullString Then GoTo Exit_Here
FormIDArr = Split(strControlAddress, FormIDFormSep)
' Because there's always a trailing closing mark (easier to handle buidling address), we skip the last array
' value, as it's always (or supposed to be...) empty.
ControlDepth = UBound(FormIDArr) - LBound(FormIDArr)
' Split out the form's Specific Information to use the details.
FormInfo = Split(FormIDArr(CurrentDepth), FormIDHWNDSep)
' The specific control is located in the 3rd element, zero referenced, so 2.
Set ControlTarget = StartingForm.Controls(FormInfo(2))
' If ControlDepth is 1 (control is on passed form) you can skip the hard and slow work of digging.
If ControlDepth > 1 Then
For CurrentDepth = 1 To ControlDepth - 1
' Note: you start at 1 because you already did the first one above.
' Split out the form's Specific Information to use the details.
FormInfo = Split(FormIDArr(CurrentDepth), FormIDHWNDSep)
Set TargetForm = ControlTarget.Form
Set ControlTarget = TargetForm.Controls(FormInfo(2))
Next CurrentDepth
End If
Exit_Here:
Set GetControlByAddress = ControlTarget
End Function
Required Helper Functions
Note, I use a property for the separators as there is some user locale handling (no included), and it also ensures that if we do change the separator it remains consistent. In this example, I simply set them to a character which is unlikely to be used in a form name. You will need to ensure your forms don't use the separator characters.
Public Function hasParent(ByRef p_form As Form) As Boolean
' Borrowed concept from https://nolongerset.com/get-top-form-by-control/
' and modified for our uses.
On Error Resume Next
hasParent = (Not p_form.Parent Is Nothing)
Err.Clear ' The last line of this will cause an error. Clear it so it goes away.
End Function
Private Function GetFormObjectByCtl(ByRef ctl As Object, _
ByRef ReturnTopForm As Boolean, Optional ByRef strControlAddress As String) As Form
strControlAddress = GetControlAddress(ctl, ctl.Parent) & strControlAddress
If TypeOf ctl.Parent Is Form Then
If ReturnTopForm Then
If hasParent(ctl.Parent) Then
'Recursively call the function if this is a subform
' and we need the top form
Set GetFormObjectByCtl = GetFormObjectByCtl( _
ctl.Parent, ReturnTopForm, strControlAddress)
Exit Function
End If
End If
Set GetFormObjectByCtl = ctl.Parent
Else
'Recursively call the function until we reach the form
Set GetFormObjectByCtl = GetFormObjectByCtl( _
ctl.Parent, ReturnTopForm, strControlAddress)
End If
End Function
Public Function GetFormByCtl(ctl As Object, Optional ByRef strControlAddress As String) As Form
Set GetFormByCtl = GetFormObjectByCtl(ctl, False, strControlAddress)
End Function
Public Function GetTopFormByCtl(ctl As Object, Optional ByRef strControlAddress As String) As Form
Set GetTopFormByCtl = GetFormObjectByCtl(ctl, True, strControlAddress)
End Function
Public Property Get FormIDHWNDSep() As String
FormIDHWNDSep = "|"
End Property
Public Property Get FormIDFormSep() As String
FormIDFormSep = ";"
End Property
Interesting. I don't think you can.
As you have seen, the parent of whtControl is its form, frmBaby.
The parent of that one is frmMain. The subform control is not part of the object chain when "going up", only when going down.
If you always use the naming scheme as in the question, you could do something like this (air code):
strSubform = whtControl.Parent.Name
strSubformCtrl = "sub" & strSubform
Set ctlSubform = whtControl.Parent.Parent(strSubformCtrl)
In access I am trying to not let the user exit a textbox unless they have filled it out (i.e. not left it null). This is to be done in a function in order to cut down on code. In VBA is there some way to stop the user from exiting the function? (I know about setting the focus but I need the code to work from a multitude of different textboxes)
For reference my current code is as follows;
Function Reload()
If IsNull(EmployeeID.Value) Or IsNull([First Name].Value) Or IsNull([Surname].Value) Or IsNull(DOB.Value) Or IsNull(Position.Value) Or IsNull(Position.Value) Or IsNull(Mobile.Value) Or IsNull(Email.Value) Or IsNull(Address.Value) Or IsNull(Suburb.Value) Or IsNull(Postcode.Value) Or IsNull([Start Date].Value) Or IsNull(UserLogin.Value) Or IsNull(UserPassword.Value) Then
MsgBox "Please fill out all fields"
Else
DoCmd.RunCommand acCmdSaveRecord
Form.Refresh
End If
End Function
Thanks
The best technique I know is to use the BeforeUpdate event to run data validation. Using your if statements if the data is not valid then set
Cancel = True
and the data will not write. You would probably prefer to disable the default record navigation and form close buttons and use custom buttons so that you can trap the invalid data error and prevent moving to a new record or closing the form. But even if you allow the user to use the built in navigation buttons or close button Access will throw up error messages about being unable to save the current record and prompt the user if he wants to proceed.
You can also go a step further and captue which fields are invalid and present a message box.
Msgbox ("The following fields were left blank and must be entered to save this record:" & vbCrLf & "Field 1" & vbCrLf & "Field 2")
A little modification of the text input limiter i use in our chat room should help. New function I have called it MustINPUT and call it on the LostFocus of the text boxes that you don't want to move from with out input.
Private Sub MyTextBox_LostFocus()
Call MustINPUT (Me.MyTextBox, 0)
End Sub
Just change the message for your users.
Sub MustINPUT(ctl As Control, iMaxLen As Integer)
'Call MustINPUT(Me.txtSayThis, 0)
If Len(ctl.Text) = iMaxLen Then
MsgBox "Please Type something", vbExclamation, "Input Needed"
ctl.Text = Left(ctl.Text, iMaxLen)
ctl.SelStart = iMaxLen
End If
End Sub
Hope this help. DR ,
Hopefully this makes sense. I'm frustrated that I cannot figure this out. I have a simple Access 2010 database. I have a simple form inside it that helps the user input some specific information. This data entry situation can occur on two other forms in the database. Rather than have two copies of the "helper" form where the VBA code has hard-coded control references, I wanted to make it more universal by passing the name of the form that calls it by using the openArgs parameter.
When the time comes to transfer the values BACK to the form that needs the information, the helper form attempts to do this like so:
Private Sub cmdOk_Click()
Dim theFormName As String
Dim theForm As Form
theFormName = Me.OpenArgs
Set theForm = Forms.Item(theFormName)
If Not IsNull(theForm.Name) Then
theForm.txtLongitude.Value = Me.lblLongitude.Caption
theForm.txtLatitude.Value = Me.lblLatitude.Caption
End If
DoCmd.Close acForm, Me.Name, acSaveNo
End Sub
The variable theForm is populated correctly and theForm.Name returns the correct name of the form so that part works fine. The problem is that theForm.<controlName>.Value does not. When I run the code, I get an
application-defined or object-defined error (Run-time Error 2465)
I've tried all sorts of permutations for the control reference from the current open form to a second open form but I cannot get the syntax right. I've tried:
theForm!txtLongitude.Value ("..can't find the field txtLongitude..")
theForm.Controls("txtLongitude").Value ("..cant find the field...")
I have two suggestions. If one works, let me know and I'll edit my answer to only include the one that works.
Try changing theForm.txtLongitude.Value = Me.lblLongitude.Caption
to Forms!theForm!txtLongitude.Value = Me!lblLongitutde.Caption and theForm.txtLatitude.Value = Me.lblLatitude.Caption to Forms!theForm!txtLatitude.Value = Me!lblLatitude.Caption
If you've already tried that or it doesn't work, try declaring variables and "pulling" the values out of one form before putting them in the other form. (Also make sure the data type of both are the same.)
Private Sub Command4_Click()
Dim theFormName As String
Dim theForm As Form
Dim txtLong As String
Dim txtLat As String
txtLong = Me.lblLongitude.Caption
txtLat = Me.lblLatitude.Caption
theFormName = Me.OpenArgs
Set theForm = Forms.Item(theFormName)
If Not IsNull(theForm.Name) Then
theForm.txtLongitude.Value = txtLong
theForm.txtLatitude.Value = txtLat
End If
DoCmd.Close acForm, Me.Name, acSaveNo
End Sub
I'm facing a deadend When trying to call this sub :
Public Sub backblue(ByVal frm As Form, ByVal boxname As String)
For i = 1 To 3
CType(frm.Controls(boxname & i.ToString()), TextBox).BackColor = Color.LightBlue
Next
End Sub
with button click event :
Private Sub Button1_click and bla bla....
backblue(Me, "txb1_")
End Sub
Can anybody show me a suggestion to fix the code.
It throws "Object Referrence not set to an instance bla bla" error
For information the textbox names are :
txb1_1 , txb1_2 , txb1_3
(these are some of the many textboxes in the form that i want its bakcolor changed)
and these three textboxes are already created through designer, not from execution.
i did check the textboxes names and there's nothing wrong.
the form class is also public.
if they are the only textboxs on said form you can just loop through
For Each box as Textbox In frm.Controls
box.BackColor = Color.LightBlue
Next
This error will occur if you do not declare the Form class to be public.
Also, make sure the textbox names are really correct, although this will probably cause a different error.
If you create the textboxes during execution, make sure they are initialized with New and added to the form's Controls collection.
Try this....
Public Sub backblue(ByVal frm As Form, ByVal prefix As String)
For i = 1 To 3
Dim bxName as String = prefix & i.ToString()
Dim bx as TextBox = CType(frm.Controls(bxName), TextBox)
If bx Is Nothing Then
MsgBox("Unable to find text box " +bxName)
Dim mtch() As Control = frm.Controls.Find(bxName, true)
If mtch.Length> 0 then
bx = mtch(0)
Else
Continue For
End if
End If
Bx.BackColor = Color.LightBlue
Next
End Sub
Although, a better solution would be to either create the textboxes inside a control and pass that control to BackBlue or to create an collection that has the controls and pass that in. Which brings up what is most likely yor problem your control is contained in a sub component and thus is not in the main form control collection
Alternative, you could use either the tag of the control or create a component control that implements IExtenderProvider and add it to the form --all of the above would effectively allow you to define the controls and/how they should be handled at designtime.
It may really seem that the names generated by this loop may not be the names of the original textboxes. My suggestion is before setting this Color property verify that the names generated by this loop are indeed the actual names. Maybe output this in a messagebox:
MessageBox.Show(boxname & i.ToString()) for each loop before you set the property