Abstracting database access

In order to connect to the database, we are going to use an abstraction layer by utilizing node-dbi. This allows us to transparently use MySQL at a later point in time, without the need to change the code that does database operations.

First, we should change our spec in order to have it expect actual database content. A request to /api/keywords/ should return a JSON structure that carries an array of objects, where each object represents a keyword with its ID, value, and the ID of its category:

[
   {"id": 1, "value": "Aubergine", "categoryID": 1},
   {"id": 2, "value": "Onion", "categoryID": 1},
   {"id": 3, "value": "Knife", "categoryID": 2}
 ]

A data structure like this would be stored in a relational database like this:

In this structure, keyword.categoryID is...