Adding a command of verification before upgrading or downgrading

[nevcohen]

Suppose that in one of the stages of the DB upgrade I would like to run a command that checks if I really want to run that stage.

For example, before I add a column I want to check if it was added manually exactly as I expected and then there is no need for the current step and it can be skipped.

This is how I will have, for example, a certain stage:

"""create account table

Revision ID: 1975ea83b712
Revises:
Create Date: 2011-11-08 11:40:27.089406

"""

# revision identifiers, used by Alembic.
revision = '1975ea83b712'
down_revision = None
branch_labels = None

from alembic import op
import sqlalchemy as sa

def verification_before_upgrade():
    pass

def upgrade():
    pass

def verification_before_downgrade():
    pass

def downgrade():
    pass

[zzzeek]

sounds good, alembic supports that, add it to your script.py.mako template and your migration files will be generated with that format. you can break upgrade into two separate calls like this

def verification_before_upgrade():
    pass

def upgrade():
    verification_before_upgrade()
    do_upgrade()

def do_upgrade():
    ${upgrades if upgrades else "pass"}


def verification_before_downgrade():
    pass

def downgrade():
     verification_before_downgrade()
     do_downgrade()

def do_downgrade():
    ${downgrades if downgrades else "pass"}

[nevcohen]

Cool, looks great!
Thank a lot!