python - Error creating table with foreign key constraint using SQLAlchemy-Migrate -

i'm building app in python. i'm using sqlalchemy-migrate track database schema. have table, user_category, has 2 columns: id , name. i'm trying create user table foreign key user_category table. change script creating user table follows:

from sqlalchemy import * migrate import * 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 own engine; bind migrate_engine     # metadata     meta.bind = migrate_engine     user.create()  def downgrade(migrate_engine):     # operations reverse above upgrade go here.     meta.bind = migrate_engine     user.drop() 

when run 'manage.py test' , error:

sqlalchemy.exc.noreferencedcolumnerror: not create foreignkey 'user_catego ry.id' on table 'user': table 'user_category' has no column named 'id' 

you claim "user_category" table has name , id. definition of "user_category" contains no columns @ :)