change the size of string column using sqlalchemy migrate

Why on earth have I done a table description like

CREATE TABLE address
(
  id serial NOT NULL,
  street text,
  city character varying(255),
  province character varying(10),
...

what a scrooge, 10 chars only, you can't live in saskatchewan with that. I had to migrate.

After a while I managed to get the syntax that makes it work

def upgrade(migrate_engine):
    meta.bind = migrate_engine
    address = Table('address', meta, autoload=True)
    address.c.province.alter(type=VARCHAR(length=255))

Eclipse pydev template to generate sql alchemy migrations

How often have you committed code, just to realize your missing a column in your sqlAlchemy model?
If you're using eclipse IDE, you can leverage the templates to write a migration script in no time.
Go to windows -> preferences -> PyDev -> Editor -> Templates

then create a new template with :

• name : Module: Migration SQLA
• context: New Module
• description: SQLA migration

# -*- coding: utf-8 -*-
'''
Created on ${date}

@author: ${user}
'''

from sqlalchemy import *
from migrate import *

meta = MetaData()

def upgrade(migrate_engine):
    meta.bind = migrate_engine
    some = Table('some',  meta, autoload=True)
    if not 'somename' in some.columns:
        new_col = Column('somename', Unicode(255))
        new_col.create(some)
            ${cursor}

def downgrade(migrate_engine):
    meta.bind = migrate_engine
        some = Table('some',  meta, autoload=True)
        some.c.some_col.drop()

And that's it ! you can now go into your migrations folder and do:
New -> PyDev Module, and choose your new template