Defining unique constraints

The RESTful Web Service doesn't use any constraints, and therefore, it is possible to create many drone categories with the same name. We don't want to have many drone categories with the same name. Each drone category name must be unique in the database table that persists drone categories (the drones_dronecategory table). We also want drones and pilots to have unique names. Hence, we will make the necessary changes to add unique constraints to each of the following fields:

• The name field of the DroneCategory model
• The name field of the Drone model
• The name field of the Pilot model

We will learn the necessary steps to edit existing models and add constraints to fields that are already persisted in tables and to propagate the changes in the underlying database by running the already analyzed migrations process.

Make sure you quit Django's development server. Remember that you just need to press Ctrl + C in the terminal or Command Prompt window in which it is running...