Overview

Flask-Migrate 3.0, released on April 1, 2021, improves Alembic integration and adds async operation support.

Main Features

Alembic improvements

Flask-Migrate 3.0 aligns with the latest Alembic versions with better schema change auto-detection and batch migration support.

python 
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
db = SQLAlchemy(app)
migrate = Migrate(app, db)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(100), nullable=False)
    email = db.Column(db.String(120), unique=True)

# flask db init
# flask db migrate -m 'Add user table'
# flask db upgrade

Async support

Flask-Migrate 3.0 supports async database engines via SQLAlchemy 1.4+, enabling migrations on asynchronously connected databases.

python 
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
db = SQLAlchemy(app)

# Migration with render_as_batch for SQLite
migrate = Migrate(app, db, render_as_batch=True)

# Batch migrations allow modifying columns
# on SQLite (which does not support ALTER)
# flask db migrate -m 'Modify column'
# flask db upgrade

Sources