Error creating table with foreign key constraints using SQLAlchemy-Migrate

Question

I am creating a python application. I am using sqlalchemy-migrate to track my database schema. I have a user_category table that has two columns: id and name. I am trying to create a user table with a foreign key in the user_category table. My script change to create a user table is as follows:

from sqlalchemy import *
from migrate import *
from migrate.changeset import *

meta = MetaData()
user_category = Table('user_category', meta)

user = Table('user', meta,
    Column('id', Integer, primary_key=True),
    Column('email', String(255)),
    Column('first_name', String(40)),
    Column('surname', String(40)),
    Column('password', String(255)),
    Column('user_category', Integer, ForeignKey("user_category.id")),
)

def upgrade(migrate_engine):
    # Upgrade operations go here. Don't create your own engine; bind migrate_engine
    # to your metadata
    meta.bind = migrate_engine
    user.create()

def downgrade(migrate_engine):
    # Operations to reverse the above upgrade go here.
    meta.bind = migrate_engine
    user.drop()

When I run 'manage.py test', I get an error:

sqlalchemy.exc.NoReferencedColumnError: Could not create ForeignKey 'user_catego
ry.id' on table 'user': table 'user_category' has no column named 'id'

Answer 1

You state that the table "user_category" has a name and an identifier. The definition of "user_category" does not contain columns at all :)

Answer 2

, user_category , , SQLAlchemy :

from sqlalchemy import *
from migrate import *
from migrate.changeset import *

meta = MetaData()

user = Table('user', meta,
    Column('id', Integer, primary_key=True),
    Column('email', String(255)),
    Column('first_name', String(40)),
    Column('surname', String(40)),
    Column('password', String(255)),
    Column('user_category', Integer, ForeignKey("user_category.id")),
)

def upgrade(migrate_engine):
    _t = sa.Table('user_category', meta, autoload=True)
    meta.bind = migrate_engine
    user.create()

:)