为什么我在进行Alembic迁移时遇到问题

问题描述

项目结构(仅包含数据库迁移的目录):

Project structue(only directory with DB migrations):

--db_manage:
  alembic.ini
  --alembic:
    env.py
    script.py.mako
    README
    --versions:
      #migration files

当我尝试运行命令: python db_manage/alembic/env.py 时，我的响应如下:

When I try to run command: python db_manage/alembic/env.py, I have response like:

Traceback (most recent call last):
  File "db_manage/alembic/env.py", line 8, in <module>
    config = context.config
AttributeError: module 'alembic.context' has no attribute 'config'

在这种情况下，我会遇到问题?
广告
文件 alembic.ini :

In which case I have that problem?
P.S.
File alembic.ini:

# A generic, single database configuration.

[alembic]
# path to migration scripts
script_location = alembic

# 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

# version location specification; this defaults
# to numus/versions.  When using multiple version
# directories, initial revisions must be specified with --version-path
# version_locations = %(here)s/bar %(here)s/bat numus/versions

# the output encoding used when revision files
# are written from script.py.mako
# output_encoding = utf-8

sqlalchemy.url = postgresql://test:oe50yxXOspYDsaXSO7Gf@localhost/test


# 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

文件 env.py :

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
target_metadata = None

# 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()

推荐答案

尝试调用迁移工具的方式有两点不对.首先，您应该使用 alembic 脚本，而不要尝试直接运行 env.py .从教程:

There are 2 things wrong in the way you try to invoke the migration tool. Firstly, you should use the alembic script instead of trying to run the env.py directly. From the tutorial:

第二，尽管您可以将 alembic.ini 保留在任何地方，但是默认行为是在当前目录中查找:

Secondly, though you can keep your alembic.ini wherever, the default behaviour is to look in the current directory:

因此，如果将其保存在其他位置，则必须使用 -c 或-config 开关指​​示该位置.例如:

So if it is held somewhere else, you must instruct alembic about the location using the -c, or --config, switch. For example:

alembic --config db_manage/alembic.ini

这篇关于为什么我在进行Alembic迁移时遇到问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！