Question

I have a database package which contains some modules namely student_table and a db module,

in student_table I have definition it’s definition like this

from sqlalchemy import Table, MetaData, String, Column, Integer
metadata = MetaData()

class User(object):
        def __init__(self, user_id, name):
                self.user_id = user_id
                self.name = name

user_table = Table('twitter_user', metadata,
        Column('id', Integer, primary_key=True), 
        Column('name', String(100))
)

and in db.py I have database create functions, which like this

def prepareDB():
    """
    sets global variables based to access database
    """
    read_settings()
    engine = create_engine('mysql://'+setting_data["database_username"]+':'+setting_data["database_password"]+'@'+setting_data["database_host"]+'/'+setting_data["database_name"]+'?charset=utf8')
    Session = sessionmaker(bind=engine)
    global session
    session = Session()
    metadata.create_all(engine)
    mapper(database.User, database.user_table)

my problem is metadata is required by db module to create engine and also by student module for definition however I don’t see a way of doing so without creating cyclic dependency.

what can I do rectify this situation.

Answer 1

I just moved constant to separate file , now everything works fine.