Alembic 自动生成未检测到当前状态

Question

问题

我正在使用 Alembic 自动生成来迁移一些模型更改。我运行了一次 alembic 修订/升级，它正确地创建了我的表并将 alembic_version 表添加到我的数据库中。当我再次运行修订/升级命令时，尽管没有对模型进行任何更改，它仍会尝试重新创建表

alembic.command.revision(cfg, autogenerate=True)
INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.
INFO  [alembic.autogenerate.compare] Detected added table 'alias.alias'

正如您在此处看到的，它正在尝试添加表 alias.alias，即使它已经存在于我的数据库中并且是由 Alembic 在第一个修订/升级命令中创建的。

可以预见的是，当我尝试运行第二次升级时，我得到了错误

psycopg2.errors.DuplicateTable: relation "alias" already exists

当前设置

env.py

import sys
import os
sys.path.insert(0, '/tmp/')

from logging.config import fileConfig
from sqlalchemy import engine_from_config
from sqlalchemy import pool
from alembic import context
from models.Base import Base
from models import Alias

config = context.config

fileConfig(config.config_file_name)

target_metadata = Base.metadata

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()

别名.py

from sqlalchemy import Column, Integer, String
from models.Base import Base


class Alias(Base):
    __tablename__ = 'alias'
    __table_args__ = {'schema': 'alias'}

    id = Column(Integer, primary_key=True)
    chart_config = Column(String)
    name = Column(String, nullable=False, unique=True)
    display_name = Column(String)
    datasets = Column(String)

Base.py

from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()

预期结果

如何让 alembic 检测到 alias.alias 表已经存在？它应该自动生成一个空的修订。在我的 2 次修订/升级运行期间，模型 Alias.py 完全是静态的

Answer 1

通过编辑 alembic 的 env.py 以包含架构来解决

    with connectable.connect() as connection:
    context.configure(
        connection=connection, target_metadata=target_metadata,
        include_schemas = True # Include this
    )

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