On Wed, Aug 22, 2012 at 12:51 PM, David McKeone <davidmcke...@gmail.com> wrote: > I've been using SQLAlchemy with Flask via the Flask extension > Flask-SQLAlchemy. Everything works great so far, but I foresee a potential > problem once I start to use my database model outside of Flask. In the > future I'd like to be able to use my models with non-Flask SQLAlchemy (a > worker daemon process or with a PySide interface). "Well just use standard > SQLAlchemy," you may say, " and fore-go the use of the extension". That was > my first thought, but sadly some useful extensions (notably > Flask-DebugToolbar) seem to like using the extension version and it is nice > to be able to have Flask manage the database sessions in the way that it > does. I'd like to not throw the baby out with the bath water. > > I realize that this is somewhat specific to Flask, but is there a way that I > could do both? Can I create models with standard SQLAlchemy declarative and > then somehow inject them into Flask-SQLAlchemy's way of doing things? > > If it helps with the solution, I don't need to use any of the Model specific > methods that Flask-SQLAlchemy provides (get_or_404, paginate, etc..) and I > also specify a __tablename__ for all of my models, so I don't rely on > Flask-SQLAlchemy generating that for me. > > I took a look at the source of Flask-SQLAlchemy > (https://github.com/mitsuhiko/flask-sqlalchemy/blob/master/flask_sqlalchemy.py) > and from what I can tell it seems that it's using Flask's signalling > capabilities by customizing SQLAlchemy's session and mapper, but that is > where my understanding ends (I'm still new to this whole stack, Python, > Flask, SQLAlchemy) and I could use some pointers for how to proceed. > > > To visualize what I'm talking about, here are the two types of models. A > basic Flask-SQLAlchemy model looks like > (http://packages.python.org/Flask-SQLAlchemy/quickstart.html#a-minimal-application): > > from flask import Flask > from flask.ext.sqlalchemy import SQLAlchemy > > app = Flask(__name__) > app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db' > > db = SQLAlchemy(app) > > class User(db.Model): > id = db.Column(db.Integer, primary_key=True) > username = db.Column(db.String(80), unique=True) > email = db.Column(db.String(120), unique=True) > > def __init__(self, username, email): > self.username = username > > self.email = email > > > def __repr__(self): > return '<User %r>' % self.username > > > Note the db.Model, db.Integer and db <dot> everything. > > The plain declarative SQLAlchemy equivalent would be > (http://flask.pocoo.org/docs/patterns/sqlalchemy/): > > > from sqlalchemy import Column Integer, String, create_engine > from sqlalchemy.orm import scoped_session, sessionmaker > from sqlalchemy.ext.declarative import declarative_base > > engine = create_engine('sqlite:////tmp/test.db', convert_unicode=True) > db_session = scoped_session(sessionmaker(autocommit=False, autoflush=False, > bind=engine)) > Base = declarative_base() > Base.query = db_session.query_property() > > > class User(Base): > __tablename__ = 'users' > > id = Column(Integer, primary_key=True) > name = Column(String(50), unique=True) > email = Column(String(120), unique=True) > > def __init__(self, name=None, email=None): > self.name = name > self.email = email > > def __repr__(self): > return '<User %r>' % (self.name) >
>From a very quick read of the Flask-SQLAlchemy docs, I would have thought you could just use your flask-based classes in non-Flask-based apps without any issue. The quickstart guide that you referenced above illustrates a command-line session using them, so there's no reason why you couldn't do the same in a worker process. Have you already tried it and found that it doesn't work? Simon -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
