Simplest way of Exception Handling specially for database applications

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Introduction

This article and the source provided demonstrate how you can handle exceptions in .NET applications in a generic way. This will ensure that there are no unhandled exceptions in your application thread.

Background

Exception handling is an important part of all applications. A few days ago, I was writing a database oriented application that consisted of over 100 forms. During the design of my application, I got different ways of exception handling, but actually I was in search of a way that was the shortest and one that requires minimum lines of code. For this project, I wrote about 10 to 12 lines of code.

Using the code

For handling exceptions on application thread level, I handle the application's exception event as follows:

static void Main() 
{ 
  Application.ThreadException+= new 
     System.Threading.ThreadExceptionEventHandler(Application_ThreadException); 
  Application.Run(new testExceptionHandler()); 
}

Now, whenever there is any exception that occurs in an application thread, this event will be called.

As I have already stated, it was a database application, now there was a challenge of how I will identify specific exceptions like primary key violation etc..

For this, in the MDI form in that application, I declared a string variable that will later contain the active form name.

Fortunately I was using SqlClient that has a SqlException class, this will be thrown if there is any database related issue. I handle this as follows:

private static void Application_ThreadException(object sender, 
                         System.Threading.ThreadExceptionEventArgs e)
{
   try
   {
        if(e.Exception is SqlException)
        {
             SqlException ex = (SqlException)e.Exception; 
             if (ex.Number == 547)
                ErrorMessage("Record cannot be deleted or changed " + 
                               "as it is being used somewhere else");
    
             else if (ex.Number == 2627)
                ErrorMessage("Record cannot be saved, as another " + 
                             "record with this key already exists");
        
             else
                ErrorMessage(ex.Message.ToString());
        }
        else
             ErrorMessage("System Error :"+e.Exception.Message.ToString());

    }
    catch(Exception ex)
    {
        ErrorMessage("System Error: Reporting to log");
    }
}

sqlexception object contains a number attribute that identifies the type of sqlexception thrown.

I have tested this method in my application, it is running well. For a more descriptive message I have used the form name of the active form for intimating the user about the problem.

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