File name presists in Dir() function over multiple sessions - vba

Question

I have some code in a Excel VBA macro and it seems like its persisting values between sessions. The issue is with the BtnUpdate_Click event, the message box doesnt trigger even if the file path in NewDataFilePath is invalid.
Public NewDataFilePath As String
Private Sub BtnFileBrowse_Click()
Dim fdlg As FileDialog
Set fdlg = Application.FileDialog(msoFileDialogOpen)
fdlg.Title = "Select New Dataset"
fdlg.Filters.Clear
fdlg.Filters.Add "Excel Files Only", "*.xls; *.xlsx"
fdlg.Show
If fdlg.SelectedItems.Count <> 0 Then
TxtFilePath = fdlg.SelectedItems(1)
End If
NewDataFilePath = TxtFilePath.Text
End Sub
Private Sub BtnUpdate_Click()
Dim a As String
a = Dir(NewDataFilePath)
If Not Dir(NewDataFilePath) <> "" Then
MsgBox """ & NewDataFilePath & "" is not a valid file path"
End If
End Sub
I added the string a in the event handler to try and debug the code and its showing me some interesting results:
I have a breakpoint on the if statement in BtnUpdate_Click.
Then i stop debugging the macro and re-run it. if i invoke BtnUpdate_Click without selecting another file the Dir() function seems to keep the last file name:
Any ideas why this could happen?

Answer 1

Of course there is no persistence of any variable value once you stop a macro
While the observed behavior is due to the following:
1) FileDialog object keeps the last path chosen in its IntialFileName property
2) Dir(path) function with an empty string as "path" would return the first file in the IntialFileName path stored by last FileDialog run
so when you re-run the macro:
NewDataFilePath is an empty string
a = Dir(NewDataFilePath), would return the first file in the IntialFileName path matching the filters (if any)
What above as the answer to your question
While you could consider the following "nuance" of your code:
Private Sub BtnUpdate_Click()
If NewDataFilePath <> "" Then 'if 'NewDataFilePath' has been set
Dim a As String
a = Dir(NewDataFilePath)
If Not Dir(NewDataFilePath) <> "" Then MsgBox """ & NewDataFilePath & "" is not a valid file path"
Else 'otherwise
MsgBox "No file path specified!", vbCritical ' inform the user to do so
End If
End Sub

Answer 2

Try this code
Public NewDataFilePath As String
Private Sub BtnFileBrowse_Click()
Dim fdlg As FileDialog
Set fdlg = Application.FileDialog(msoFileDialogOpen)
fdlg.Title = "Select New Dataset"
fdlg.Filters.Clear
fdlg.Filters.Add "Excel Files Only", "*.xls; *.xlsx"
fdlg.Show
If fdlg.SelectedItems.Count <> 0 Then
NewDataFilePath = fdlg.SelectedItems(1)
End If
End Sub
Private Sub BtnUpdate_Click()
Dim a As String
a = Dir(NewDataFilePath)
If DoesFileExist(NewDataFilePath) And NewDataFilePath <> "" Then
MsgBox NewDataFilePath & " is a valid file path"
Else
MsgBox NewDataFilePath & " NOT a valid file path"
End If
End Sub
Function DoesFileExist(filePath) As Boolean
DoesFileExist = Dir(filePath) <> ""
End Function