Exception error messages

[riechan]

Can anyone give me some easy to understand exception-handled error messages, like this:

...
Catch parameter As SqlException
            MsgBox("Unable to save record due to invalid parameters.", MsgBoxStyle.Information, "Unable To Save Record")
            dbConn.Close()
...

for the following events:

- During database connection error
- Error occurred uring saving, deleting
- Unable to load data from database

And any else you guys can come up. Kindly include what kind of exception that would be as well. Thanks!

[Sabrina Gage]

Example:

sub mySub
dim sqlCn as new SqlConnection(connString)
try
sqlcn.open
'here do some thing
catch ex
msgbox ex.message
finally
sqlCn.close
end try
end sub

________________
Sabrina Gage

[formlesstree4]

Catch parameter As SqlException

You would just call this:

parameter.Message

To get an easy to understand message.

[riechan]

What kinds of exceptions does this line encompass/include?

Catch ex as Exception
...

And what does the Finally block do?

[formlesstree4]

Catch ex As Exception allows the programmer to 'catch' errors in their code. So lets say...you do this:

Try
   'Stuff here trips an error
   Catch ex As Exception
        Messagebox.show(ex.ToString)
   Finally
        'Do ending stuff here
End Try

You can display the error message, which gives you a message and a stack trace as well as Inner Exceptions. These are crucial to debugging your code.

Finally allows you to do any ending code that your sub might need to do. Generally used for disposing of objects (I think...don't quote me on that).

[riechan]

Okay, am not quoting you on it.

So, you can place stuff like closing the database connection in the Finally clause, just like in the post above. What if I use this:

Try
...
Catch ex as exception
msgbox(ex.message)
Finally
...
End Try

Is ex.ToString the same as ex.message?

[formlesstree4]

No, ex.Message is just the error message. ex.ToString is the entire thing. message, stacktrace, inner exception.

[riechan]

No, ex.Message is just the error message. ex.ToString is the entire thing. message, stacktrace, inner exception.

I guess you can use the ex.ToString for debugging. I'm thinking of using the ex.Message for displaying error messages that are a little bit more understandable to common users.

Would you mind checking this for me, and tell me if there's anything wrong in it? Do I need to check if the dbconn is still open in the Finally clause, or is it okay if I just close it right away?

            Try
            ...
            Catch parameter As SqlException
            MsgBox("An unexpected error occurred during saving. Please try again.", MsgBoxStyle.Information, "Error Occurred During Save")
        Catch invalidparameter As InvalidOperationException
            MsgBox(invalidparameter.Message, MsgBoxStyle.Exclamation, "Invalid Operation Error Occurred")
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Exclamation, "Runtime Error")
        Finally
            If dbConn.State = ConnectionState.Open Then
                dbConn.Close()
            End If
        End Try

[jmcilhinney]

So, you can place stuff like closing the database connection in the Finally clause, just like in the post above.

You put code in the finally block that you need to execute whether an exception is thrown or not. The difference between using the Finally block and putting the code after the End Try is that the Finally block is executed even if there's a Return statement in the Try or Catch block.

Is ex.ToString the same as ex.message?

You don't need to ask us things that you can simply test for yourself. It would have taken about 30 seconds to write some code and run it and see what each produced. If your attitude is "look first, ask questions later" then you'll learn far quicker. If your first thought is to get someone else to do it for you then you're not going to learn as fast.

[formlesstree4]

You put code in the finally block that you need to execute whether an exception is thrown or not. The difference between using the Finally block and putting the code after the End Try is that the Finally block is executed even if there's a Return statement in the Try or Catch block.

Quite useful to know, thanks for clearing that up.