One very important task you have as a developer is to keep track of errors. Errors you ask? ‘Errors’? ‘Not me, I write bug free code!’. Ok Mr. Programming God, but for the rest of us mortals, we have to do something to keep track of all the human errors that get embedded into our code. There are many different ways to store these errors, some people do it in flat files, others in databases. We won’t be talking about where to store these errors, just how to get them from silverlight.
The problem
Web applications have always presented a particular problem when it comes to catching errors and logging them in a central place. First, with Javascript it is difficult to know when an error has occurred and hasn’t been caught already and if so, it’s difficult to do anything after that as many javascript errors will break the app entirely and not run anymore code.
The Solution… A Solution
Silverlight attempts to simplify this process by having a central place to catch any unhandled exceptions and then do something with them. You can catch them in the App.xaml.css file. Here is an example:
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e) { //Ignores logging if your debugging if (!System.Diagnostics.Debugger.IsAttached) { /*TODO: Some method to save the the error to a file or database by using e.ExceptionObject.Message, e.ExceptionObject.StackTrace */ e.Handled = true; ChildWindow errorWin = new ErrorWindow("Error", "An Error has been logged")); errorWin.Show(); } }
Does this mean that we don’t need to do any try/catches? No, we still need to handle errors and do something with them, but in the event that we miss an error, it will be caught here and logged so that we can more easily debug the released code.
Tags: C#, Debugging, Silverlight