Wordz – abstracting the database
In this section, we will apply what we’ve learned to our Wordz application and create a port suitable for fetching the words to present to a user. We will write the adapters and integration tests in Chapter 14, Driving the Database Layer.
Designing the repository interface
The first job in designing our port is to decide what it should be doing. For a database port, we need to think about the split between what we want our domain model to be responsible for and what we will push out to the database. The ports we use for a database are generally called repository interfaces.
Three broad principles should guide us:
- Think about what the domain model needs – why do we need this data? What will it be used for?
- Don’t simply echo an assumed database implementation – don’t think in terms of tables and foreign keys at this stage. That comes later when we decide how to implement the storage. Sometimes...
