db.session.dirty trick

gistfile1.py

from flask.ext.sqlalchemy import SQLAlchemy
from flask import Flask


app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://db_user@localhost/employees'
db = SQLAlchemy(app)


class User(db.Model):
    __tablename__ = 'myTable'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)
    age = db.Column(db.Integer)
    enabled = db.Column(db.Integer)


def update_():
    for user in User.query:
        if user.age > 40:
            user.enabled = 1
    if db.session.dirty:
        try:
            db.session.commit()
        except Exception:
            db.session.rollback()

if __name__ == '__main__':
    update_()