Flask-Migrate

We want to allow the user to check or uncheck todo items in our Todo app, to mark them as completed or not. Right now, we don't have a concept of what "completed" means in our database, which models a Todo with a single property called "description". We'd like to extend the model to also include a boolean property called "completed" in order to allow for todos to be marked as completed or not by a user on our app.

While we can do this totally using psql or another Postgres client to simply alter our table to add a new column using the ALTER TABLE ADD COLUMN command in SQL, we should use migrations to handle changes to our database schema for better maintainability and the ability to rollback quickly in case of issues.

Over the next few pages, we'll walk through how to use Flask-Migrate to add a new completed column to our to-do model.

Installing Flask-Migrate and Using the Documentation

Importing the Migrate library and creating an instance of the Migrate class

Follow along! Interactive Workspace

• Install Flask-Migrate
• Instantiate migrate