Common dialog API causes problem
Posted on 2002-05-07
I am using the Windows API to dispaly a browse for file window and return the user's selection. I previously tried using the common dialog control, but quickly found that users could have trouble with the registration of this control on their PC's, so I obtained code (by Ken Getz) to use the Windows API from a Web site. The code is shown below. I call this code as follows:
strFilter = ahtAddFilterItem(strFilter, "MS Access databases|*.mdb")
strFilename = ahtCommonFileOpenSave(Filter:=strFilter, OpenFile:=True, _
DialogTitle:="Enter path to the Franchisee Profiler data:", _
InitialDir:=strDataPath, FileName:="FPData.mdb", Flags:=ahtOFN_HIDEREADONLY)
If strFilename = "" Then
'Error - user pressed cancel
'continue with returned pathname in strFileName
When my client tries to run the application on his computer, the common dialog code runs fine. He selects the path to the backend database, and then all is OK until he closes and reopens the app. This time the tables are linked correctly, so the common dialog box does not show at startup (although it is still used to perform an import/export function if desired). However, whenever he opens a report or runs a query that uses the Format function, he is either prompted for parameter value "Format", or he receives a message "The expression is typed incorrectly, or it is too complex to be evaluated. For example, a numeric expression may contain too many complicated elements. Try simplifying the expression by assigning part of the expression to variables.".
No references are missing and the application compiles OK, but somehow the Format function is no longer recognised. There is no reference to comdlg32.dll - I presume that it is part of Windows and always guaranteed to be present.
I thought that using the Windows API was supposed to solve all problems with installation, but since this code uses the library comdlg32.dll and there are differenet versions of that, I'm not so sure.
I am at a loss to know what to do - all help would be appreciated.
Here is the API code:
'***************** Code Start **************
'This code was originally written by Ken Getz.
'It is not to be altered or distributed,
'except as part of an application.
'You are free to use it in any application,
'provided the copyright notice is left unchanged.
' Code courtesy of:
' Microsoft Access 95 How-To
' Ken Getz and Paul Litwin
' Waite Group Press, 1996
lStructSize As Long
hwndOwner As Long
hInstance As Long
strFilter As String
strCustomFilter As String
nMaxCustFilter As Long
nFilterIndex As Long
strFile As String
nMaxFile As Long
strFileTitle As String
nMaxFileTitle As Long
strInitialDir As String
strTitle As String
Flags As Long
nFileOffset As Integer
nFileExtension As Integer
strDefExt As String
lCustData As Long
lpfnHook As Long
lpTemplateName As String
Declare Function aht_apiGetOpenFileName Lib "comdlg32.dll" _
Alias "GetOpenFileNameA" (OFN As tagOPENFILENAME) As Boolean
Declare Function aht_apiGetSaveFileName Lib "comdlg32.dll" _
Alias "GetSaveFileNameA" (OFN As tagOPENFILENAME) As Boolean
Declare Function CommDlgExtendedError Lib "comdlg32.dll" () As Long
Global Const ahtOFN_READONLY = &H1
Global Const ahtOFN_OVERWRITEPROMPT = &H2
Global Const ahtOFN_HIDEREADONLY = &H4
Global Const ahtOFN_NOCHANGEDIR = &H8
Global Const ahtOFN_SHOWHELP = &H10
' You won't use these.
'Global Const ahtOFN_ENABLEHOOK = &H20
'Global Const ahtOFN_ENABLETEMPLATE = &H40
'Global Const ahtOFN_ENABLETEMPLATEHANDLE = &H80
Global Const ahtOFN_NOVALIDATE = &H100
Global Const ahtOFN_ALLOWMULTISELECT = &H200
Global Const ahtOFN_EXTENSIONDIFFERENT = &H400
Global Const ahtOFN_PATHMUSTEXIST = &H800
Global Const ahtOFN_FILEMUSTEXIST = &H1000
Global Const ahtOFN_CREATEPROMPT = &H2000
Global Const ahtOFN_SHAREAWARE = &H4000
Global Const ahtOFN_NOREADONLYRETURN = &H8000
Global Const ahtOFN_NOTESTFILECREATE = &H10000
Global Const ahtOFN_NONETWORKBUTTON = &H20000
Global Const ahtOFN_NOLONGNAMES = &H40000
' New for Windows 95
Global Const ahtOFN_EXPLORER = &H80000
Global Const ahtOFN_NODEREFERENCELINKS = &H100000
Global Const ahtOFN_LONGNAMES = &H200000
Function ahtCommonFileOpenSave( _
Optional ByRef Flags As Variant, _
Optional ByVal InitialDir As Variant, _
Optional ByVal Filter As Variant, _
Optional ByVal FilterIndex As Variant, _
Optional ByVal DefaultExt As Variant, _
Optional ByVal FileName As Variant, _
Optional ByVal DialogTitle As Variant, _
Optional ByVal hwnd As Variant, _
Optional ByVal OpenFile As Variant) As Variant
' This is the entry point you'll use to call the common
' file open/save dialog. The parameters are listed
' below, and all are optional.
' Flags: one or more of the ahtOFN_* constants, OR'd together.
' InitialDir: the directory in which to first look
' Filter: a set of file filters, set up by calling
' AddFilterItem. See examples.
' FilterIndex: 1-based integer indicating which filter
' set to use, by default (1 if unspecified)
' DefaultExt: Extension to use if the user doesn't enter one.
' Only useful on file saves.
' FileName: Default value for the file name text box.
' DialogTitle: Title for the dialog.
' hWnd: parent window handle
' OpenFile: Boolean(True=Open File/False=Save As)
' Return Value: Either Null or the selected filename
Dim OFN As tagOPENFILENAME
Dim strFilename As String
Dim strFileTitle As String
Dim fResult As Boolean
' Give the dialog a caption title.
If IsMissing(InitialDir) Then InitialDir = CurDir
If IsMissing(Filter) Then Filter = ""
If IsMissing(FilterIndex) Then FilterIndex = 1
If IsMissing(Flags) Then Flags = 0&
If IsMissing(DefaultExt) Then DefaultExt = ""
If IsMissing(FileName) Then FileName = ""
If IsMissing(DialogTitle) Then DialogTitle = ""
If IsMissing(hwnd) Then hwnd = Application.hWndAccessApp
If IsMissing(OpenFile) Then OpenFile = True
' Allocate string space for the returned strings.
strFilename = Left(FileName & String(256, 0), 256)
strFileTitle = String(256, 0)
' Set up the data structure before you call the function
.lStructSize = Len(OFN)
.hwndOwner = hwnd
.strFilter = Filter
.nFilterIndex = FilterIndex
.strFile = strFilename
.nMaxFile = Len(strFilename)
.strFileTitle = strFileTitle
.nMaxFileTitle = Len(strFileTitle)
.strTitle = DialogTitle
.Flags = Flags
.strDefExt = DefaultExt
.strInitialDir = InitialDir
' Didn't think most people would want to deal with
' these options.
.hInstance = 0
'.strCustomFilter = ""
'.nMaxCustFilter = 0
.lpfnHook = 0
'New for NT 4.0
.strCustomFilter = String(255, 0)
.nMaxCustFilter = 255
' This will pass the desired data structure to the
' Windows API, which will in turn it uses to display
' the Open/Save As Dialog.
If OpenFile Then
fResult = aht_apiGetOpenFileName(OFN)
fResult = aht_apiGetSaveFileName(OFN)
' The function call filled in the strFileTitle member
' of the structure. You'll have to write special code
' to retrieve that if you're interested.
If fResult Then
' You might care to check the Flags member of the
' structure to get information about the chosen file.
' In this example, if you bothered to pass in a
' value for Flags, we'll fill it in with the outgoing
' Flags value.
If Not IsMissing(Flags) Then Flags = OFN.Flags
ahtCommonFileOpenSave = TrimNull(OFN.strFile)
ahtCommonFileOpenSave = vbNullString
Private Function TrimNull(ByVal strItem As String) As String
Dim intPos As Integer
intPos = InStr(strItem, vbNullChar)
If intPos > 0 Then
TrimNull = Left(strItem, intPos - 1)
TrimNull = strItem
Function ahtAddFilterItem(strFilter As String, _
strDescription As String, Optional varItem As Variant) As String
' Tack a new chunk onto the file filter.
' That is, take the old value, stick onto it the description,
' (like "Databases"), a null character, the skeleton
' (like "*.mdb;*.mda") and a final null character.
If IsMissing(varItem) Then varItem = "*.*"
ahtAddFilterItem = strFilter & _
strDescription & vbNullChar & _
varItem & vbNullChar