Display\Capture InnerException Message

Question

I was using the following to provide more information on a common exception that can occour in a piece of my code, the only problem is this errors if an exception is generated that has no InnerException message.

Catch ex As Exception
     'MessageBox.Show(ex.Message) 'If there is no InnerException.
     MessageBox.Show(ex.InnerException.InnerException.Message)
End Try

Is there a better method of doing this?

Answer 1

Just surround it by an If not nothing, but if you're doing it a lot, write a quick helper function like:

Private Function GetErrorText(ByVal ex As Exception) As String
    Dim err As String = ex.Message
    If ex.InnerException IsNot Nothing Then
        err &= " - More details: " & ex.InnerException.Message
    End If
    Return err
End Function

Then you can just do MessageBox.Show(GetErrorText(ex)).

Answer 2

You can make a recursive function to keep grabbing the inner exceptions as long as they exist, that way you will get the full details if you have a single exception or 3 exceptions layered within each other.

Public Function ReadException(ByVal ex As Exception) As String
  Dim msg As String = ex.Message
  If ex.InnerException IsNot Nothing Then
    msg = msg & vbCrLf & "---------" & vbCrLf & ReadException(ex.InnerException)
  End If
  Return msg
End Function

and in your catch:

Catch ex As Exception
     MessageBox.Show(ReadException(ex))
End Try