classic-sql-storage 0.0.2

Provides primitives for contextual transactions processing with SQLALchemy and base for repository class

Classic SQL Storage

This package provides contextual transactions processing for SQLAlchemy and base for pattern "Repository".

Part of project "Classic".

Usage:

from classic.sql_storage import TransactionContext
from sqlalchemy import create_engine, text


engine = create_engine('sqlite:///')

transaction = TransactionContext(bind=engine)


# As context manager:
with transaction:
    transaction.current_session.execute(
        text('SELECT 1')
    )


# As decorator:
@transaction
def some_work():
    transaction.current_session.execute(
        text('SELECT 1')
    )


# Propagation:
@transaction
def complex_function():
    """Doing complex work with db.
    Session will be commited only after finish of complex_function call.
    TransactionContext will count all calls, and will commit or rollback session
    only in last call.
    """
    some_work()
    some_work()
    some_work()
    
    with transaction:
        transaction.current_session.execute(
            text('SELECT 1')
        )


# Automatic rollback
@transaction
def function_with_error():
    """Changes, made by some_work, will be cancelled after raising error"""
    some_work()
    raise ValueError()