No matter how hard we try, sometimes the code that we use and write will raise an exception.

Usually, these exceptions are thrown in, well, exceptional circumstances, but that does not detract from the fact that we should understand which parts of our application may raise an exception and whether or not we want to handle the exception at the point of invocation or simply let it bubble up the call stack to another frame.

For our current application, there are several types of exceptions that we would like to handle in a graceful manner rather than let it crash the entire Python process and bring everything to an ugly, screeching halt.

In the previous chapter, we glossed over some of the necessary exception handling that needs to exist in most Flask and SQLAlchemy-based applications (or nearly any other database abstraction, for that matter), but the importance of handling these exceptions when they do arise cannot be understated. With this in mind, let's create...