8.27. Migration Create

8.27.1. Initialize

$ alembic init migrations
  Creating directory /tmp/project/migrations/versions ...  done
  Generating /tmp/project/migrations/script.py.mako ...  done
  Generating /tmp/project/migrations/env.py ...  done
  Generating /tmp/project/migrations/README ...  done
  Generating /tmp/project/migrations/alembic.ini ...  done
  Please edit configuration/connection/logging settings in '/tmp/project/migrations/alembic.ini' before proceeding.

8.27.2. Configure

$ vim alembic.ini +55
$ grep 'sqlalchemy.url' alembic.ini
sqlalchemy.url = sqlite:///tmp.db

8.27.3. Initial Revision

$ alembic revision -m "Initial revision"
  Generating /tmp/project/migrations/versions/ad4de013e007_initial_revision.py ...  done

8.27.4. Upgrade

$ alembic upgrade heads
INFO  [alembic.runtime.migration] Context impl SQLiteImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> ad4de013e007, Initial revision

# Show alembic where you have your ORM models
# Set proper value for ``target_metadata``
$ vim env.py +18

8.27.5. Autogenerate

$ alembic revision --autogenerate -m "User Model"
INFO  [alembic.runtime.migration] Context impl SQLiteImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected added table 'user'
  Generating /private/tmp/project/versions/21fa69deb961_user_model.py ...  done

8.27.6. Upgrade

$ alembic upgrade head
INFO  [alembic.runtime.migration] Context impl SQLiteImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade ad4de013e007 -> 21fa69deb961, User Model

$ alembic upgrade 21fa69deb961  # you can also use shorter, but still unique hash

8.27.7. Downgrade

$ alembic downgrade <hash>
$ alembic downgrade -1  # one revision back