ACC: Cannot Open Multiple Instances of the Same FormID: Q101312
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Advanced: Requires expert coding, interoperability, and multiuser skills.
When you try to open a second instance of an open form with an OpenForm
macro action, the instance of the form that is already open is activated.
NOTE: In Microsoft Access for Windows 95 version 7.0 there is a new feature
that allows multiple instances of the same form. For more information about
this feature, search on the phrase "Displaying Multiple Instances of a
Form" using Answer Wizard in Microsoft Access for Windows 95 Help.
You can have only one copy of a form open at a time.
NOTE: This article assumes that you are familiar with Access Basic and with
creating Microsoft Access applications using the programming tools provided
with Microsoft Access. For more information on Access Basic, please refer
to the "Introduction to Programming" manual in Microsoft Access version
1.x, or the "Building Applications" manual in version 2.0.
The following information describes how to create and use an Access Basic
function called OpenFormInstance(), which allows you to open more than one
copy of the same form in Microsoft Access. To make OpenFormInstance work,
you must first make <x> number of copies of your original form, giving each
copy a numeric suffix greater than zero. That is, if your form is called
"Customers," make copies of the form renaming them to "Customers1,"
"Customers2," "Customers3," and so forth.
When OpenFormInstance() is invoked with "Customers," it checks to see if a
copy of the form is available for display. It returns the following error
message if all instances are currently open:
Could not open form "Customers"
Please close another instance and try again.
'*****************************************************************
' DECLARATION SECTION
'*****************************************************************
Option Explicit
'*****************************************************************
' FUNCTION: OpenFormInstance()
'
' PURPOSE:
' Allows you to open more than one copy of the same form
' on screen at a time.
'
' PREREQUISITES:
' You must make X number of copies of the the
' form, renaming them with a numeric suffix greater than zero.
' Example:
'
' "Customers1," "Customers2," "Customers3," ...
'
' REQUIRES:
' Function IsLoaded() - Determines if form is loaded.
' Function GetFormNames() - Supplied in this module.
'
' ARGUMENTS:
' FormName - The generic name of the form to open.
' Example:
'
' "Customers"
'
' RETURNS:
' True - if an instance of FormName was opened.
' False - if no instance of FormName was found or all available
' instances are active.
'
' NOTES:
' You can customize the OpenForm action in the code below to add
' additional (optional) parameters, such as a Where condition or
' or alternate view.
'
'********************************************************************
Function OpenFormInstance (ByVal FormName As String)
Dim Count, i, Msg As String, InstanceCount
ReDim Names(0) As String
' Get a list of all the forms in the current database.
Count = GetFormNames(Names())
' Loop through the list of forms for a match with
' .. the requested form.
For i = 0 To Count - 1
' Is the name of the form, minus the suffix, the same?
If FormName = Left(Names(i), Len(FormName)) Then
' .. is the suffix a number greater than zero?
If Val(Mid(Names(i), Len(FormName) + 1)) > 0 Then
' Count the number of instances.
InstanceCount = InstanceCount + 1
' If the form is NOT loaded,load it.
If Not IsLoaded(Names(i)) Then
DoCmd OpenForm Names(i)
OpenFormInstance = True
Exit Function
End If
End If
End If
Next i
' No form was found or all instances are being used.
OpenFormInstance = False
' If no instance was found, just return.
If InstanceCount = 0 Then Exit Function
' If all instances are being used, display error message.
Msg = "Couldn't open form """ & FormName & """."
Msg = Msg & Chr$(13) & Chr$(13)
Msg = Msg & "Please close another instance and try again."
MsgBox Msg, 48
End Function
'****************************************************************
' FUNCTION: GetFormNames()
'
' PURPOSE:
' Fills the string array with a list of forms names.
'
' ARGUMENTS:
' Names - A single dimensional array of type string.
'
' RETURN:
' The number(zero based) of names stored in the Names array.
'
' NOTES:
' This function uses information stored in the
' MySysObject table of the currently opened database.
' The system tables are undocumented and are subject to
' change in future versions of Microsoft Access.
'
'****************************************************************
Function GetFormNames (Names() As String)
Dim db As Database, ss As Snapshot
Dim Count, SQL
Dim Msg As String
SQL = "Select Name,Type from MSysObjects Where Type="
SQL = SQL & "-32768 And Left(Name,1)<>'~' Order By Name;"
Set db = CurrentDB()
Set ss = db.CreateSnapshot(SQL)
ss.MoveLast
If ss.RecordCount > 0 Then
ReDim Names(0 To ss.RecordCount - 1)
Else
GetFormNames = 0
Exit Function
End If
ss.MoveFirst
Count = 0
Do While Not ss.EOF
Names(Count) = ss![name]
Count = Count + 1
ss.MoveNext
Loop
GetFormNames = ss.RecordCount
End Function
MsgBox Screen.ActiveForm![ControlName]
Function MyFunction(MyForm)
MsgBox Forms(MyForm)![ControlName]
End Function
RunCode
Function Name: =MyFunction(Screen.ActiveForm.FormName) This behavior no longer occurs in Microsoft Access version 7.0.
Microsoft Access, "Introduction to Programming," version 1.1, Chapter 7,
"Forms and Report Variables"
Microsoft Access, "Building Applications," version 2.0, Chapter 4, "Using
Forms to Collect, Display, and Filter Information"
Additional query words: open twice isloaded running
Keywords : kbusage FmsOthr
Version : 1.0 1.1 2.0
Platform : WINDOWS
Issue type : kbprb Last Reviewed: March 25, 1999