当我想使用alembic进行自动生成迁移时出现错误。
项目树：
- alembic.ini
- axis.py
- tree.txt
-
alembic
- env.py
- README
- script.py.mako
versions
# 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
# timezone to use when rendering the date
# within the migration file as well as the filename.
# string value is passed to dateutil.tz.gettz()
# leave blank for localtime
# timezone =
# 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 alembic/versions. When using multiple version
# directories, initial revisions must be specified with --version-path
# version_locations = %(here)s/bar %(here)s/bat alembic/versions
# the output encoding used when revision files
# are written from script.py.mako
# output_encoding = utf-8
sqlalchemy.url = mysql+pymysql://root:**********$@localhost/amatdb_test
[post_write_hooks]
# post_write_hooks defines scripts or Python functions that are run
# on newly generated revision scripts. See the documentation for further
# detail and examples
# format using "black" - use the console_scripts runner, against the "black" entrypoint
# hooks=black
# black.type=console_scripts
# black.entrypoint=black
# black.options=-l 79
# Logging configuration
[loggers]
keys = root,sqlalchemy,alembic
[handlers]
keys = console
[formatters]
keys = generic
[logger_root]
level = WARN
handlers = console
qualname =
[logger_sqlalchemy]
level = WARN
handlers =
qualname = sqlalchemy.engine
[logger_alembic]
level = INFO
handlers =
qualname = alembic
[handler_console]
class = StreamHandler
args = (sys.stderr,)
level = NOTSET
formatter = generic
[formatter_generic]
format = %(levelname)-5.5s [%(name)s] %(message)s
datefmt = %H:%M:%S
axis.py
from sqlalchemy import create_engine
import pymysql
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint
Base = declarative_base()
engine = create_engine('mysql+pymysql://root:*******$@localhost/amatdb_test')
#The axis on which the tests are executed
class AXIS(Base):
__tablename__ = 'Axis'
id_axis = Column(Integer, primary_key = True)
name_axis = Column(String(10), nullable=False)
env.py
from logging.config import fileConfig
from sqlalchemy import engine_from_config
from sqlalchemy import pool
from alembic import context
import sys
import os
sys.path.insert(0, os.getcwd())
print(sys.path)
from axis import Base
print(Base.metadata.sorted_tables)
# 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 = 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,
dialect_opts={"paramstyle": "named"},
)
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()
我的问题的解释
首先，我创建了第一个自动生成迁移：Alembic版本--autogenerate
迁移文件似乎正确。
"""Creation table
Revision ID: dcd02a3f6ff9
Revises:
Create Date: 2020-06-03 08:47:48.198022
"""
from alembic import op
import sqlalchemy as sa
# revision identifiers, used by Alembic.
revision = 'dcd02a3f6ff9'
down_revision = None
branch_labels = None
depends_on = None
def upgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.create_table('Axis',
sa.Column('id_axis', sa.Integer(), nullable=False),
sa.Column('name_axis', sa.String(length=10), nullable=False),
sa.PrimaryKeyConstraint('id_axis')
)
# ### end Alembic commands ###
def downgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.drop_table('Axis')
# ### end Alembic commands ###
然后，我运行：Alembic升级头
我的数据库已创建。
因此，我在表轴上添加了一个名为“ test”的新列。
test = Column(String(10), default=None)
并且我第二次运行：alembic revision --autogenerate
我获得此迁移文件
"""Ajout colonne test dans axis
Revision ID: 283ca08aec66
Revises: dcd02a3f6ff9
Create Date: 2020-06-03 08:49:19.717515
"""
from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects import mysql
# revision identifiers, used by Alembic.
revision = '283ca08aec66'
down_revision = 'dcd02a3f6ff9'
branch_labels = None
depends_on = None
def upgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.create_table('Axis',
sa.Column('id_axis', sa.Integer(), nullable=False),
sa.Column('name_axis', sa.String(length=10), nullable=False),
sa.Column('test', sa.String(length=10), nullable=True),
sa.PrimaryKeyConstraint('id_axis')
)
op.drop_table('axis')
# ### end Alembic commands ###
def downgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.create_table('axis',
sa.Column('id_axis', mysql.INTEGER(), autoincrement=True, nullable=False),
sa.Column('name_axis', mysql.VARCHAR(length=10), nullable=False),
sa.PrimaryKeyConstraint('id_axis'),
mysql_collate='utf8mb4_0900_ai_ci',
mysql_default_charset='utf8mb4',
mysql_engine='InnoDB'
)
op.drop_table('Axis')
# ### end Alembic commands ###
如您所见，Alembic尝试重新创建表格轴。因此，当我运行时：alembic upgrade head
由于轴已经存在，我得到一个错误。
我想念什么？
为什么Alembic无法检测到现有表？
感谢您的时间和考虑
尝试使用小写的表格名称，即用axis代替Axis。我不确定mysql甚至不支持大写表名，但这可能会导致问题。