VBScript -- Using error handling

Question

I want to use VBScript to catch errors and log them  ie on error  log something   then resume the next line of the script   For example    On Error Resume Next  Do Step 1  Do Step 2  Do Step 3   When an error occurs on step 1  I want it to log that error  or perform other custom functions with it  then resume at step 2  Is this possible  and how can I implement it   EDIT  Can I do something like this    On Error Resume myErrCatch  Do step 1  Do step 2  Do step 3  myErrCatch   log error Resume Next

User · Answer

You can regroup your steps functions calls in a facade function :

sub facade()
    call step1()
    call step2()
    call step3()
    call step4()
    call step5()
end sub

Then, let your error handling be in an upper function that calls the facade :

sub main()
    On error resume next

    call facade()

    If Err.Number <> 0 Then
        ' MsgBox or whatever. You may want to display or log your error there
        msgbox Err.Description
        Err.Clear
    End If

    On Error Goto 0
end sub

Now, let's suppose step3() raises an error. Since facade() doesn't handle errors (there is no On error resume next in facade()), the error will be returned to main() and step4() and step5() won't be executed.

Your error handling is now refactored in 1 code block

User · Answer

VBScript has no notion of throwing or catching exceptions  but the runtime provides a global Err object that contains the results of the last operation performed  You have to explicitly check whether the Err Number property is non-zero after each operation   On Error Resume Next  DoStep1  If Err Number  lt  gt  0 Then   WScript Echo  Error in DoStep1     amp  Err Description   Err Clear End If  DoStep2  If Err Number  lt  gt  0 Then   WScript Echo  Error in DoStop2    amp  Err Description   Err Clear End If   If you no longer want to continue following an error after that block s completed   call this  On Error Goto 0   The  On Error Goto  label   syntax is supported by Visual Basic and Visual Basic for Applications  VBA   but VBScript doesn t support this language feature so you have to use On Error Resume Next as described above

User · Answer

I m exceptionally new to VBScript  so this may not be considered best practice or there may be a reason it shouldn t be done this that way I m not yet aware of  but this is the solution I came up with to trim down the amount of error logging code in my main code block   Dim oConn  connStr Set oConn   Server CreateObject  ADODB Connection   connStr    Provider SQLOLEDB Server XX UID XX PWD XX Databse XX   ON ERROR RESUME NEXT  oConn Open connStr If err Number  lt  gt  0 Then   showError     End If   Sub ShowError         You could write the error details to the console        errDetail     lt script gt    amp         console log  Description     amp  err Description  amp         amp         console log  Error number     amp  err Number  amp         amp         console log  Error source     amp  err Source  amp         amp          lt  script gt        Response Write errDetail                  you could display the error info directly in the page        Response Write  Error Description     amp  err Description      Response Write  Error Source     amp  err Source      Response Write  Error Number     amp  err Number           or you could execute additional code when an error is thrown         Insert error handling code here      err clear End Sub

User · Answer

Note that On Error Resume Next is not set globally  You can put your unsafe part of code eg into a function  which will interrupted immediately if error occurs  and call this function from sub containing precedent OERN statement   ErrCatch    Sub ErrCatch       Dim Res  CurrentStep      On Error Resume Next      Res   UnSafeCode 20  CurrentStep      MsgBox  ErrStep    amp  CurrentStep  amp  vbCrLf  amp  Err Description  End Sub  Function UnSafeCode Arg  ErrStep       ErrStep   1     UnSafeCode   1    Arg - 10       ErrStep   2     UnSafeCode   1    Arg - 20       ErrStep   3     UnSafeCode   1    Arg - 30       ErrStep   0 End Function

[vbscript] VBScript -- Using error handling

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