How to stop code from executing after error? - vba

Question

My form allows users to filter by various controls, including a search box for strings. A separate function, CalculateSearchString, processes this search field for filtering (keywords, exact phrases etc); and within this function I use error handling to trap errors caused by incorrect user input (i.e. mucking up the punctuation). The error handling works without a hitch, but I would like the code to come to a complete stop if the search input is incorrect.
What I want:
user inputs incorrectly formatted search string, clicks on the filter
function CalculateSearchFilter throws error. Message box: "fix your search terms!"
code stops completely, and filter is not applied
What actually happens:
user inputs incorrectly formatted search string, clicks on the filter
function CalculateSearchFilter throws error. Message box: "fix your search terms!" Exit function
calling procedure cmdFilterOn still runs, applying an incomplete filter (as though the search box had been empty)
Question: How do I halt code execution completely, not just in the function but in its calling procedure(s)? The function is used in more than one place, so merging it with the calling procedure is not practical.
Private Sub cmdFilterOn()
Dim strSearch As String
strSearch = CalculateSearchFilter
'do more stuff
End Sub
Private Function CalculateSearchFilter() As String
On Error GoTo ErrHandler
'do stuff
If 'user input is wrong, then raise a custom error:
Err.Raise 50000
End If
ExitHandler:
Exit Function
ErrHandler:
If Err.Number = 50000 Then msgbox "Fix your search terms!"
Resume ExitHandler
End Sub
Private Sub cmdYetAnotherButton()
'which also calls on CalculateSearchFilter
End Sub
Moving the input validation to the calling procedure isn't practical either, as it would force me to repeat much of the code in CalculateSearchFilter().
(As I was writing this another solution occurred to me, which is to set CalculateSearchFilter = "an error occurred" in the function error handler, and in the calling procedure
If CalculateSearchFilter = "an error occurred" Then Exit Sub
...but is there a more "official" answer?)

Answer 1

You could try to return a boolean value instead
Option Explicit
Private Sub cmdFilterOn()
Dim strSearch As String
If CalculateSearchFilter(strSearch) Then
'do more stuff
End If
End Sub
Private Function CalculateSearchFilter(ByRef strSearch As String) As Boolean
On Error GoTo ErrHandler
'do stuff
If 'user input is wrong, then raise a custom error:
Err.Raise 50000
End If
CalculateSearchFilter = True
ExitHandler:
Exit Function
ErrHandler:
If Err.Number = 50000 Then MsgBox "Fix your search terms!"
CalculateSearchFilter = False
Resume ExitHandler
End Function
Private Sub cmdYetAnotherButton()
'which also calls on CalculateSearchFilter
End Sub
Alternative:
As mentioned in the comments if you would like to get a string back then I would return an empty string. I would not recommend to return a string like an error occured or whatsoever
Option Explicit
Private Sub cmdFilterOn()
Dim strSearch As String
strSearch = CalculateSearchFilter
If Len(strSearch) > 0 Then
'do more stuff
End If
End Sub
Private Function CalculateSearchFilter() As String
On Error GoTo ErrHandler
'do stuff
If 'user input is wrong, then raise a custom error:
Err.Raise 50000
End If
ExitHandler:
Exit Function
ErrHandler:
If Err.Number = 50000 Then MsgBox "Fix your search terms!"
CalculateSearchFilter = vbNullString
Resume ExitHandler
End Function
Private Sub cmdYetAnotherButton()
'which also calls on CalculateSearchFilter
End Sub