How do I manage relationships in SQLAlchemy with async?

Can you explain how to manage relationships in SQLAlchemy when using async?

Sure! In SQLAlchemy, you can define relationships using the relationship() function. When working with async, you need to ensure that your session is also async.

What are the key differences between sync and async relationships?

The main difference is that async relationships require an async session and use await for queries, while sync uses standard session methods.

Can you provide a code example for an async relationship?

Absolutely! Here's a simple example:

from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
from sqlalchemy.orm import sessionmaker, relationship

class Parent(Base):
    __tablename__ = 'parents'
    id = Column(Integer, primary_key=True)
    children = relationship('Child', back_populates='parent')

class Child(Base):
    __tablename__ = 'children'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('parents.id'))
    parent = relationship('Parent', back_populates='children')

How do I handle queries with these relationships in async?

You can use await session.execute() for queries. For example:

async with AsyncSession() as session:
    result = await session.execute(select(Parent).options(selectinload(Parent.children)))
    parents = result.scalars().all()