Using Flask-SQLAlchemy without Flask

Question

I had a small web service built using Flask and Flask-SQLAlchemy that only held one model. I now want to use the same database, but with a command line app, so I'd like to drop the Flask dependency.

My model looks like this:

class IPEntry(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    ip_address = db.Column(db.String(16), unique=True)
    first_seen = db.Column(db.DateTime(),
        default = datetime.datetime.utcnow
    )
    last_seen = db.Column(db.DateTime(),
        default = datetime.datetime.utcnow
    )

    @validates('ip')
    def validate_ip(self, key, ip):
        assert is_ip_addr(ip)
        return ip

Since db will no longer be a reference to flask.ext.sqlalchemy.SQLAlchemy(app), how can I convert my model to use just SQLAlchemy. Is there a way for the two applications (one with Flask-SQLAlchemy the other with SQLAlchemy) to use the same database?

Answer 1

you can do this to replace db.Model:

from sqlalchemy import orm
from sqlalchemy.ext.declarative import declarative_base
import sqlalchemy as sa

base = declarative_base()
engine = sa.create_engine(YOUR_DB_URI)
base.metadata.bind = engine
session = orm.scoped_session(orm.sessionmaker())(bind=engine)

# after this:
# base == db.Model
# session == db.session
# other db.* values are in sa.*
# ie: old: db.Column(db.Integer,db.ForeignKey('s.id'))
#     new: sa.Column(sa.Integer,sa.ForeignKey('s.id'))
# except relationship, and backref, those are in orm
# ie: orm.relationship, orm.backref
# so to define a simple model

class UserModel(base):
    __tablename__ = 'users' #<- must declare name for db table
    id = sa.Column(sa.Integer,primary_key=True)
    name = sa.Column(sa.String(255),nullable=False)

then to create the tables:

 base.metadata.create_all()

Answer 2

Check this one github.com/mardix/active-alchemy

Active-Alchemy is a framework agnostic wrapper for SQLAlchemy that makes it really easy to use by implementing a simple active record like api, while it still uses the db.session underneath. Inspired by Flask-SQLAlchemy