Splitting our application into multiple files

Now that our directory structure is in order, we need to start dissecting our application script and splitting it up into our module files. We'll also need to create our model class.

Open up your data_entry_app.py file from Chapter 5, Reducing User Error with Validation and Automation, and let's begin!

Creating the models module

When your application is all about data, it's good to begin with the model. Remember that the job of a model is to manage the storage, retrieval, and processing of our application's data, usually with respect to its persistent storage format (in this case, CSV). To accomplish this, our model should contain all the knowledge about our data.

Currently, our application has nothing like a model; knowledge about the application's data is scattered the form fields, and the Application object simply takes whatever data the form contains and stuffs it directly into a CSV file when...