Persistence

In Chapter 5, Data, we created a framework for capturing and holding data in memory.  However, this is only half of the story, as without persisting the data to some external destination, it will be lost as soon as we close the application. In this chapter, we will build on our earlier work and save our data to disk in a SQLite database so that it can live on beyond the lifetime of the application. Once saved, we will also build methods for finding, editing, and deleting our data. To get all these operations for free in our various data models, we will extend our data entities so that they can load and save to our database automatically, without us having to write boilerplate code in each class. We will cover the following topics:

• SQLite
• Primary keys
• Creating clients
• Finding clients
• Editing clients
• Deleting clients