Manage database upgrades with Flask-migrate

When we upgrade the system, we often encounter the need to update the server-side data structure, and so on, the way is by hand-written alter SQL script processing, often found missing, resulting in the program published to the server will not work properly.

Now we can use the Flask-migrate plugin to solve it, flask-migrate plug-in is based on alembic,alembic is a data migration tool developed by the famous SQLAlchemy author.

Here's how:

1. Installing the Flask-migrate Plugin

Install Flask-migrate

2. Modify the code in the Flask app section to add migrate-related command

db = SQLAlchemy (APP) migrate = migrate (app, db) Manager = Manager (APP) Manager.add_command ('db', Migratecommand)     

3. Initialization

$ Python app.py db init

4. Data migration, automatically create migration code

$ Python app.py db migrate

5. Updating the database

$ Python app.py db upgrade

If there is a model change in the back, you only need to repeat the 4th and 5 steps in the development environment.

In the server side only need to perform a 5th step to achieve the database migration.

Manage database upgrades with Flask-migrate