Solved

How can I create a custom exception class in vb.net

Posted on 2007-11-29
6
2,631 Views
Last Modified: 2012-08-14
I am using vb.net 2003 to create a custom exception handling class.  The code that I am currently using works fine but I will need to use this exception handling pages containing data connections, queries, etc. and would like to just access a custom class.   Here is a short version of the code that is working and the code snippet attached is what I have in the class so far.  The line ex.message.tostring is not working.  Any help or direction on how to accomplish this would be appreciated.  Thank-you very much.
        Try
        Catch ex As Exception
            'WORKING CODE
            'Dim file As New System.IO.StreamWriter(Server.MapPath("..\ErrorLog.txt"), True)
            'file.WriteLine(FormatDateTime(Date.Now, DateFormat.GeneralDate))
            'file.WriteLine(ex.Message.ToString())
            'file.WriteLine(ex.Source.ToString())
            'file.WriteLine(ex.StackTrace.ToString())
            'file.Close()
            'Response.Redirect("http://localhost/NetTestDocs/ErrorsRedirectPage.aspx")
            'END OF CODE
        Finally
            conn.Close()
            conn.Dispose()
        End Try
    End Sub
Public Class ErrorsClass

    Public ex As Exception

    Sub writererror()

        'Dim file As New System.IO.StreamWriter(Server.MapPath("..\ErrorLog.txt"), True)

        Dim file As New System.IO.StreamWriter(HttpContext.Current.Server.MapPath("..\ErrorLog.txt"), True)

        file.WriteLine(FormatDateTime(Date.Now, DateFormat.GeneralDate))

        'file.WriteLine(ex.Message.ToString())

        file.Close()

    End Sub
 

End Class

Open in new window

0
Comment
Question by:lnshop
  • 3
  • 2
6 Comments
 
LVL 25

Expert Comment

by:InteractiveMind
ID: 20379240
In the catch block, re-throw your exception, but to your custom class.

An example here:
http://www.vbdotnetheaven.com/UploadFile/susanabraham/CustomExceptionHandlingvb11122005021337AM/CustomExceptionHandlingvb.aspx?ArticleID=4ce8bdfe-1a63-44da-a4a3-f8e796d63302


When you say that ex.Message.ToString() is "not working", do you mean that it's returning an empty string?

If you replace these two lines:

         'file.WriteLine(ex.Message.ToString())
         'file.WriteLine(ex.Source.ToString())

with

         'file.WriteLine(ex.ToString())

does it include the expected message? (Wishful thinking here)
0
 
LVL 44

Expert Comment

by:Arthur_Wood
ID: 20381315
you can also create your own Exception, by crearing a class the inherits from Exception:


     
Public Class MyException Inherits Exception

   Private _exceptionMessage as String

   Public ReadOnly Property ExceptionMessage() as String

      Property Get

       Return _exceptionMessage 

      End Get

   End property

   Public Sub New(ByVal Message as String)

      MyBase.New("Custom Error")

      _exceptionMessage = Message

   End Sub
 

End Class
 
 

Then you can use it like this:
 

     Try

        If someCondition then

            Throw New MyException("Something dreadful has happened")

        End if

     Catch ex as MyException

          MessageBox.Show(ex.ExceptionMessage, vbOkOnly

     Finally

     End try

Open in new window

0
 

Author Comment

by:lnshop
ID: 20385195
Thank-you so much for your help.  I have the error message working now but I am having a problem adding the error source.  Attached is the class code.  How can I add the error source to the text file.   I have tried adding source as a property and have tried adding innerException and can't get this to work. If you could help me with adding the exception source, I would appreciate it very much.

'CODE IN VB CODE BEHIND
        Catch ex As Exception
            'REFERENCE TO ERRORS CLASS
            Dim myerror As ErrorsClass
            myerror = New ErrorsClass(ex.Message)
            myerror.writererror()

'ERRORS CLASS

Imports System.Exception

Public Class ErrorsClass

    Inherits Exception

    Private _exceptionMessage As String

    Public ReadOnly Property exceptionMessage() As String

        Get

            Return _exceptionMessage

        End Get

    End Property

    Public Sub writererror()

        Dim file As New System.IO.StreamWriter(HttpContext.Current.Server.MapPath("..\ErrorLog.txt"), True)

        file.WriteLine(FormatDateTime(Date.Now, DateFormat.GeneralDate))

        file.WriteLine(Message.ToString())

        file.Close()

    End Sub

End Class

Open in new window

0
3 Use Cases for Connected Systems

Our Dev teams are like yours. They’re continually cranking out code for new features/bugs fixes, testing, deploying, testing some more, responding to production monitoring events and more. It’s complex. So, we thought you’d like to see what’s working for us.

 
LVL 44

Accepted Solution

by:
Arthur_Wood earned 250 total points
ID: 20386916
you need a way to create the message text.  Try this:


Imports System.Exception

Public Class ErrorsClass

    Inherits Exception

    Private _exceptionMessage As String

    Private _errorSource as String

    Public ReadOnly Property exceptionMessage() As String

        Get

            Return _exceptionMessage

        End Get

    End Property
 

    Public Sub New(byVal Message as String, byVal Source as string)

        _exceptionMessage = Message

        _errorSource = Source

    End Sub

    Public Sub writererror()

        Dim file As New System.IO.StreamWriter(HttpContext.Current.Server.MapPath("..\ErrorLog.txt"), True)

        file.WriteLine("Error occurred at: " & FormatDateTime(Date.Now, DateFormat.GeneralDate))

        file.WriteLine("Source = " & _errorSource)

        file.WriteLine("Error Message = " & _exceptionMessage)

        file.Close()

    End Sub

End Class
 
 

Then when you want to Throw the Exception:

    Try

       Code that creates the original exception

       .

       .

    Catch ex as Exception

       Throw New ErrorClass(ex.Message, "Procedure Name where the Error occurred")

    End Try
 

AW

Open in new window

0
 

Author Comment

by:lnshop
ID: 20396830
Thank-you very much.  That works great.  I have the source and stack trace being written to the error log now.
0
 
LVL 44

Expert Comment

by:Arthur_Wood
ID: 20398683
Glad to be of assistance

AW
0

Featured Post

3 Use Cases for Connected Systems

Our Dev teams are like yours. They’re continually cranking out code for new features/bugs fixes, testing, deploying, testing some more, responding to production monitoring events and more. It’s complex. So, we thought you’d like to see what’s working for us.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

If you’re thinking to yourself “That description sounds a lot like two people doing the work that one could accomplish,” you’re not alone.
Real-time is more about the business, not the technology. In day-to-day life, to make real-time decisions like buying or investing, business needs the latest information(e.g. Gold Rate/Stock Rate). Unlike traditional days, you need not wait for a fe…
An introduction to basic programming syntax in Java by creating a simple program. Viewers can follow the tutorial as they create their first class in Java. Definitions and explanations about each element are given to help prepare viewers for future …
In this seventh video of the Xpdf series, we discuss and demonstrate the PDFfonts utility, which lists all the fonts used in a PDF file. It does this via a command line interface, making it suitable for use in programs, scripts, batch files — any pl…

920 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

16 Experts available now in Live!

Get 1:1 Help Now