python - 以编程方式获取 Alembic 数据库版本

Question

我正在尝试弄清楚如何使用 Alembic 获取数据库的版本。我已经将数据库设置为使用 alembic 并成功地对其执行了升级和降级。我现在想从我自己的 python 脚本中获取这个版本。

我试图为此创建一个函数

def get_current_database_version():
    path = os.path.join(os.path.dirname(__file__), os.path.pardir)
    alembic_cfg = Config(os.path.join(path, 'alembic.ini'))
    current_rev = command.current(alembic_cfg, head_only=True)
    return current_rev

此函数返回了一个NoSectionError: No section: 'formatters'

然后我转到我的 alembic.ini 文件来检查它是否有一个格式化程序区域。这是我的 alembic.ini 文件:

# A generic, single database configuration.

[alembic]
# path to migration scripts
script_location = alembic
pyramid_config_file = ../../development.ini

# template used to generate migration files
# file_template = %%(rev)s_%%(slug)s

# max length of characters to apply to the
# "slug" field
#truncate_slug_length = 40

# set to 'true' to run the environment during
# the 'revision' command, regardless of autogenerate
# revision_environment = false

# set to 'true' to allow .pyc and .pyo files without
# a source .py file to be detected as revisions in the
# versions/ directory
# sourceless = false

sqlalchemy.url = sqlite:///%(here)s/mgo.sqlite


# Logging configuration
[loggers]
keys = root,sqlalchemy,alembic

[handlers]
keys = console

[formatters]
keys = generic

[logger_root]
level = WARN
handlers = console
qualname =

[logger_sqlalchemy]
level = WARN
handlers =
qualname = sqlalchemy.engine

[logger_alembic]
level = INFO
handlers =
qualname = alembic

[handler_console]
class = StreamHandler
args = (sys.stderr,)
level = NOTSET
formatter = generic

[formatter_generic]
format = %(levelname)-5.5s [%(name)s] %(message)s
datefmt = %H:%M:%S

有人知道我做错了什么吗？谢谢

编辑:

这是我尝试使用 MigrationContext 来解决问题:

def get_database_revision():
    engine = create_engine("sqlite:///../mgo.db")
    conn = engine.connect()
    context = MigrationContext.configure(conn)
    current_rev = context.get_current_revision()
    return current_rev

它连接但没有返回。使用 sqlite 浏览器我可以看到数据库中的版本没有设置为无。

Answer 1

您可以使用MigrationContext 来get the current version :

from alembic.migration import MigrationContext
from sqlalchemy import create_engine

engine = create_engine("postgresql://mydatabase")
conn = engine.connect()

context = MigrationContext.configure(conn)
current_rev = context.get_current_revision()

在 env.py 中你可以使用:

from alembic import context
migration_context = context.get_context()
current_rev = context.get_current_revision()

最后，它基本上归结为连接到数据库并查看 alembic_version 表。它包含迁移版本作为值，这是数据库当前所在的位置(根据 alembic)。因此，您可以随心所欲地编写代码，只要那是您最终要做的。