如何将alembic连接到sqlalchemy.orm.DeclarativeBase模型？

Question

我是 FastAPI 新手。我目前正在研究FastAPI用户https://fastapi-users.github.io/fastapi-users/10.4/configuration/databases/sqlalchemy/

我的问题是：鉴于我已经拥有 sqlalchemy.Table 类的模型，如何使用 alembic 迁移“User”模型？我到底如何编辑“User”类？

完整代码在这里：

auth/database.py

from datetime import datetime
from typing import AsyncGenerator

from fastapi import Depends
from fastapi_users.db import SQLAlchemyBaseUserTable, SQLAlchemyUserDatabase
from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.orm import DeclarativeBase

from config import DB_HOST, DB_NAME, DB_PASS, DB_PORT, DB_USER

from sqlalchemy.orm import Mapped, mapped_column
from sqlalchemy import Boolean, ForeignKey, Integer, String, TIMESTAMP, Column

from models.models import role

DATABASE_URL = f"postgresql+asyncpg://{DB_USER}:{DB_PASS}@{DB_HOST}:{DB_PORT}/{DB_NAME}"


class Base(DeclarativeBase):
    pass


class User(Base, SQLAlchemyBaseUserTable[int]):
    email: Mapped[str] = mapped_column(
        String(length=320), unique=True, index=True, nullable=False
    )
    hashed_password: Mapped[str] = mapped_column(
        String(length=1024), nullable=False
    )
    is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
    is_superuser: Mapped[bool] = mapped_column(
        Boolean, default=False, nullable=False
    )
    is_verified: Mapped[bool] = mapped_column(
        Boolean, default=False, nullable=False
    )
    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    username: Mapped[str] = mapped_column(String, nullable=False)
    registered_at: Mapped[str] = mapped_column(TIMESTAMP, default=datetime.utcnow)
    role_id: Mapped[int] = mapped_column(Integer, ForeignKey(role.c.id))


engine = create_async_engine(DATABASE_URL)
async_session_maker = async_sessionmaker(engine, expire_on_commit=False)


async def create_db_and_tables():
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)


async def get_async_session() -> AsyncGenerator[AsyncSession, None]:
    async with async_session_maker() as session:
        yield session


async def get_user_db(session: AsyncSession = Depends(get_async_session)):
    yield SQLAlchemyUserDatabase(session, User)

模型/models.py

from sqlalchemy import MetaData, Table, Column, Integer, String, JSON

metadata = MetaData()

role = Table(
    "role",
    metadata,
    Column("id", Integer, primary_key=True),
    Column("name", String, nullable=False),
    Column("permissions", JSON)
)

迁移/env.py

from logging.config import fileConfig

from sqlalchemy import engine_from_config
from sqlalchemy import pool

from alembic import context

from config import DB_HOST, DB_NAME, DB_PASS, DB_PORT, DB_USER


# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
from models.models import metadata


config = context.config

section = config.config_ini_section
config.set_section_option(section, "DB_HOST", DB_HOST)
config.set_section_option(section, "DB_NAME", DB_NAME)
config.set_section_option(section, "DB_PASS", DB_PASS)
config.set_section_option(section, "DB_PORT", DB_PORT)
config.set_section_option(section, "DB_USER", DB_USER)

# Interpret the config file for Python logging.
# This line sets up loggers basically.
if config.config_file_name is not None:
    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 = 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() -> None:
    """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() -> None:
    """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()

我尝试使用 sqlalchemy.ext.declarative.declarative_base 而不是 sqlalchemy.orm.DeclarativeBase

from sqlalchemy.ext.declarative import DeclarativeMeta, declarative_base

# Declare a base from your metadata
Base: DeclarativeMeta = declarative_base(metadata=metadata)

# Create the User table with the class style
class UserTable(Base, SQLAlchemyBaseUserTable):
    # Add your columns here
    name = Column(String(50))

但是没有成功

Answer 1

在某些情况下，您必须将模型导入 env.py，因此元数据将包含有关您的模型的信息。 如果命令“alembic revision --autogenerate”没有显示任何错误，但找不到您的模型，请尝试在 env.py 中导入 User。