[Python] Flask-migrate Simple Introduction

Flask-migrate is an extension tool for handling SQLAlchemy database migrations. Manage database changes with migrate when model changes occur.

Migrate has 3 main actions, INIT, migrate and upgrade.

Take the following application as an example:

1  fromFlaskImportFlask2  fromFlask_sqlalchemyImportSQLAlchemy3  fromFlask_migrateImportMigrate4 5App = Flask (__name__)6app.config['Sqlalchemy_database_uri'] ="sqlite:///app.db"7 8db =SQLAlchemy (APP)9Migrate =Migrate (app, DB)Ten  One #Model A classUser (db. Model): -ID = db. Column (db. Integer, primary_key=True) -Name = db. Column (db. String (128))

1. Initialization

Flask DB Init

This command generates a Migrations folder in the current directory. This folder also needs to be added to version control along with other source files.

2. Generate the initial migration

Flask DB Migrate

This command generates a version folder under Migrations, which contains the corresponding versions of the database Operations py script.

Since migrate does not necessarily find all of your changes to the model, the generated py script needs to be review and edit if necessary.

For example, the table name table, the column name change, or the naming of constraints are not found. For more details of the restrictions see this: Alembic autogenerate documentation

3. Database Upgrade

Flask DB Upgrade

A final step. This command is equivalent to executing the corresponding PY version under the version folder and making a change operation to the database.

Since then, the model has changed, as long as the repeated migrate and upgrade operation can be.

To view the Help documentation:

Flask DB--help

Using Flask-script's command call, refer to the official documentation yourself: flask-migrate documentation

[Python] Flask-migrate Simple Introduction