Files
MetaORM/examples/nested_transactions.py

65 lines
2.0 KiB
Python

import asyncio
from metaorm import BaseFilter, BaseRepository, BaseTable, Field, RepositorySettings
class ProductTable(BaseTable, table=True):
__tablename__ = "products"
id: int | None = Field(default=None, primary_key=True)
name: str
price: float
class ProductFilter(BaseFilter):
name: str | None = None
class ProductRepository(BaseRepository, table=ProductTable, filter_=ProductFilter):
pass
async def main() -> None:
settings = RepositorySettings(dsn="sqlite+aiosqlite:///:memory:")
repository = ProductRepository(settings=settings)
await repository.create_tables()
# Standalone nested transaction: rollback only the inner scope
try:
async with repository.nested_transaction():
await repository.create_item(ProductTable(name="Laptop", price=999.99))
await repository.create_item(ProductTable(name="Mouse", price=29.99))
raise ValueError("Simulated error inside nested transaction")
except ValueError:
pass
count = await repository.get_items_count()
print(f"Items after standalone nested rollback: {count}") # 0
# Nested transaction inside an outer transaction
async with repository.transaction():
await repository.create_item(ProductTable(name="Keyboard", price=79.99))
try:
async with repository.nested_transaction():
await repository.create_item(
ProductTable(name="Monitor", price=299.99),
)
raise ValueError("Nested rollback")
except ValueError:
pass
# Monitor is rolled back, Keyboard stays in the outer transaction
items = [item async for item in repository.get_items()]
print(f"Items after partial rollback: {len(items)}") # 1
print(items[0].name) # Keyboard
# Verify committed results
all_items = [item async for item in repository.get_items()]
print(f"Final items: {[item.name for item in all_items]}") # ["Keyboard"]
if __name__ == "__main__":
asyncio.run(main())