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February 11, 2024 08:02
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import asyncio | |
from sqlalchemy import create_engine, Column, Integer, String, ForeignKey | |
from sqlalchemy.orm import declarative_base, relationship, selectin_polymorphic | |
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine | |
from sqlalchemy.orm import Mapped | |
from sqlalchemy.future import select | |
from sqlalchemy.ext.asyncio import ( | |
AsyncSession, | |
create_async_engine, | |
async_sessionmaker, | |
async_scoped_session, | |
) | |
DATABASE_URL = "sqlite+aiosqlite:///:memory:" | |
Base = declarative_base() | |
class GroupUserLink(Base): | |
__tablename__ = "group_user_link" | |
group_id: int = Column(Integer, ForeignKey("groups.id"), primary_key=True) | |
user_id: int = Column(Integer, ForeignKey("users.id"), primary_key=True) | |
class User(Base): | |
__tablename__ = "users" | |
id: int = Column(Integer, primary_key=True) | |
name: str = Column(String(50)) | |
groups: Mapped[list["Group"]] = relationship( | |
"Group", | |
secondary="group_user_link", | |
lazy="selectin", | |
back_populates="users", | |
) | |
def __str__(self): | |
return f"Usr:\"{self.name}\"" | |
def __repr__(self): | |
return f"<Usr:\"{self.name}\">" | |
class Group(Base): | |
__tablename__ = "groups" | |
id = Column(Integer, primary_key=True) | |
title = Column(String(100)) | |
users: Mapped[list[User]] = relationship( | |
"User", | |
secondary="group_user_link", | |
lazy="selectin", | |
) | |
def __str__(self): | |
return f"Grp:\"{self.title}\"" | |
def __repr__(self): | |
return f"<Grp:\"{self.title}\">" | |
async def get_users(self, session): | |
query = ( | |
select(User).join(GroupUserLink).where(GroupUserLink.group_id == self.id) | |
) | |
result = await session.execute(query) | |
users = result.scalars().all() | |
return users | |
engine = create_async_engine(url=DATABASE_URL, echo=False, future=True) | |
session_factory = async_sessionmaker( | |
bind=engine, | |
autoflush=False, | |
autocommit=False, | |
expire_on_commit=False, | |
) | |
async def create_tables() -> None: | |
async with engine.begin() as conn: | |
await conn.run_sync(Base.metadata.create_all) | |
async def create_group_and_users(session: AsyncSession): | |
user1 = User(name="User 1") | |
user2 = User(name="User 2") | |
user3 = User(name="User 3") | |
session.add(user1) | |
session.add(user2) | |
session.add(user3) | |
group1 = Group(title="Group 1") | |
session.add(group1) | |
group1.users.append(user1) | |
group1.users.append(user2) | |
group2 = Group(title="Group 1") | |
session.add(group2) | |
group2.users.append(user3) | |
await session.commit() | |
await session.refresh(group1) | |
await session.refresh(group2) | |
return group1, group2 | |
async def get_group_by_id(group_id: int, session): | |
result = await session.execute(select(Group).where(Group.id == group_id)) | |
group = result.scalars().first() | |
return group | |
async def get_all_groups(session): | |
result = await session.execute(select(Group)) | |
groups = result.scalars().all() | |
return groups | |
async def main(): | |
await create_tables() | |
async with session_factory() as session: | |
group1, group2 = await create_group_and_users(session) | |
print(f"Created groups: {group1}, {group2}") | |
all_groups = await get_all_groups(session) | |
for grp in all_groups: | |
retrieved_group: Group = await get_group_by_id(grp.id, session) | |
print(f"Retrieved group: {retrieved_group}, Users: {retrieved_group.users}") | |
if __name__ == "__main__": | |
asyncio.run(main()) |
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