db_migrate.py

import imp
from migrate.versioning import api
from app import db
from config import SQLALCHEMY_DATABASE_URI
from config import SQLALCHEMY_MIGRATE_REPO

migration=SQLALCHEMY_MIGRATE_REPO+'/versions/%03d_migration.py'% (
    api.db_version(SQLALCHEMY_DATABASE_URI,SQLALCHEMY_MIGRATE_REPO)+1)

tmp_module=imp.new_module('old_model')

old_model=api.create_model(SQLALCHEMY_DATABASE_URI,SQLALCHEMY_MIGRATE_REPO)

exec(old_model , tmp_module.__dict__)

script=api.make_update_script_for_model(
    SQLALCHEMY_DATABASE_URI,SQLALCHEMY_MIGRATE_REPO,tmp_module.meta,db.metadata)

open(migration,'wt').write(script)

api.upgrade(SQLALCHEMY_DATABASE_URI,SQLALCHEMY_MIGRATE_REPO)

print('New migration saved as:' + migration)
print('Current database version:'
+ str(api.db_version(SQLALCHEMY_DATABASE_URI,SQLALCHEMY_MIGRATE_REPO)))