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"""Illustrates use of the sqlalchemy.ext.asyncio.AsyncSession object
for asynchronous ORM use.
"""
from __future__ import annotations
import asyncio
from typing import Any
from typing import List
from typing import Optional
from typing import TYPE_CHECKING
from sqlalchemy import ForeignKey
from sqlalchemy.ext.asyncio import async_sessionmaker
from sqlalchemy.ext.asyncio import create_async_engine
from sqlalchemy.future import select
from sqlalchemy.orm import DeclarativeBase
from sqlalchemy.orm import Mapped
from sqlalchemy.orm import mapped_column
from sqlalchemy.orm import relationship
from sqlalchemy.orm import Session
if TYPE_CHECKING:
from sqlalchemy import ScalarResult
class Base(DeclarativeBase):
pass
class A(Base):
__tablename__ = "a"
id: Mapped[int] = mapped_column(primary_key=True)
data: Mapped[str]
bs: Mapped[List[B]] = relationship()
class B(Base):
__tablename__ = "b"
id: Mapped[int] = mapped_column(primary_key=True)
a_id = mapped_column(ForeignKey("a.id"))
data: Mapped[str]
def work_with_a_session_one(sess: Session) -> Any:
pass
def work_with_a_session_two(sess: Session, param: Optional[str] = None) -> Any:
pass
async def async_main() -> None:
"""Main program function."""
engine = create_async_engine(
"postgresql+asyncpg://scott:tiger@localhost/test",
echo=True,
)
async with engine.begin() as conn:
await conn.run_sync(Base.metadata.drop_all)
async with engine.begin() as conn:
await conn.run_sync(Base.metadata.create_all)
async_session = async_sessionmaker(engine, expire_on_commit=False)
async with async_session.begin() as session:
await session.run_sync(work_with_a_session_one)
await session.run_sync(work_with_a_session_two, param="foo")
session.add_all(
[
A(bs=[B(), B()], data="a1"),
A(bs=[B()], data="a2"),
A(bs=[B(), B()], data="a3"),
]
)
async with async_session() as session:
result = await session.execute(select(A).order_by(A.id))
r: ScalarResult[A] = result.scalars()
a1 = r.one()
a1.data = "new data"
await session.commit()
asyncio.run(async_main())
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