mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-21 08:02:07 -04:00
Mike Bayer
5fb0138a32
Using the approach introduced at https://gist.github.com/zzzeek/6287e28054d3baddc07fa21a7227904e We can now create asyncio endpoints that are then handled in "implicit IO" form within the majority of the Core internals. Then coroutines are re-exposed at the point at which we call into asyncpg methods. Patch includes: * asyncpg dialect * asyncio package * engine, result, ORM session classes * new test fixtures, tests * some work with pep-484 and a short plugin for the pyannotate package, which seems to have so-so results Change-Id: Idbcc0eff72c4cad572914acdd6f40ddb1aef1a7d Fixes: #3414
90 lines
2.3 KiB
Python
90 lines
2.3 KiB
Python
"""Illustrates use of the sqlalchemy.ext.asyncio.AsyncSession object
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for asynchronous ORM use.
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"""
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import asyncio
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from sqlalchemy import Column
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from sqlalchemy import ForeignKey
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from sqlalchemy import Integer
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from sqlalchemy import String
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from sqlalchemy.ext.asyncio import AsyncSession
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from sqlalchemy.ext.asyncio import create_async_engine
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from sqlalchemy.ext.declarative import declarative_base
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from sqlalchemy.future import select
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from sqlalchemy.orm import relationship
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from sqlalchemy.orm import selectinload
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Base = declarative_base()
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class A(Base):
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__tablename__ = "a"
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id = Column(Integer, primary_key=True)
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data = Column(String)
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bs = relationship("B")
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class B(Base):
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__tablename__ = "b"
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id = Column(Integer, primary_key=True)
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a_id = Column(ForeignKey("a.id"))
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data = Column(String)
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async def async_main():
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"""Main program function."""
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engine = create_async_engine(
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"postgresql+asyncpg://scott:tiger@localhost/test", echo=True,
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)
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async with engine.begin() as conn:
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await conn.run_sync(Base.metadata.drop_all)
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await conn.run_sync(Base.metadata.create_all)
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async with AsyncSession(engine) as session:
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async with session.begin():
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session.add_all(
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[
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A(bs=[B(), B()], data="a1"),
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A(bs=[B()], data="a2"),
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A(bs=[B(), B()], data="a3"),
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]
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)
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# for relationship loading, eager loading should be applied.
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stmt = select(A).options(selectinload(A.bs))
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# AsyncSession.execute() is used for 2.0 style ORM execution
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# (same as the synchronous API).
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result = await session.execute(stmt)
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# result is a buffered Result object.
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for a1 in result.scalars():
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print(a1)
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for b1 in a1.bs:
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print(b1)
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# for streaming ORM results, AsyncSession.stream() may be used.
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result = await session.stream(stmt)
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# result is a streaming AsyncResult object.
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async for a1 in result.scalars():
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print(a1)
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for b1 in a1.bs:
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print(b1)
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result = await session.execute(select(A).order_by(A.id))
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a1 = result.scalars().first()
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a1.data = "new data"
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await session.commit()
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asyncio.run(async_main())
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