Alembic没有检测到数据库和代码之间的差异

Question

我删除了数据库中alembic_version表的内容，然后删除了alembic / versions目录的内容。

然后我跑了：

PYTHONPATH=. alembic -c ./alembic.ini revision --autogenerate -m 'your message about the migration'

和

alembic upgrade head

但是尽管代码和数据库不匹配，但是alembic似乎什么也没做。

我做错了什么？

from __future__ import with_statement
from alembic import context
from sqlalchemy import engine_from_config, pool
from logging.config import fileConfig

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config

# Interpret the config file for Python logging.
# This line sets up loggers basically.
fileConfig(config.config_file_name)

# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
from serve_spec_guru.db_global import db_unikernelguru
from serve_spec_guru.model_documents import Documents
from serve_spec_guru.model_filesets import Filesets
from serve_spec_guru.model_hosts import Hosts
from serve_spec_guru.model_issues import Issues
from serve_spec_guru.model_messages import Messages
from serve_spec_guru.model_payments import Payments
from serve_spec_guru.model_unikernels import Unikernels
from serve_spec_guru.model_websites import Websites
from serve_spec_users.model_users import Users

target_metadata = db_guru.Base.metadata


# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.


def run_migrations_offline():
    """Run migrations in 'offline' mode.

    This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url, target_metadata=target_metadata, literal_binds=True)

    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online():
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.

    """
    connectable = engine_from_config(
        config.get_section(config.config_ini_section),
        prefix='sqlalchemy.',
        poolclass=pool.NullPool)

    with connectable.connect() as connection:
        context.configure(
            connection=connection,
            target_metadata=target_metadata
        )

        with context.begin_transaction():
            context.run_migrations()

if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()