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Database connection and session management.
Uses async SQLAlchemy with asyncpg driver.
"""
import uuid
from sqlalchemy import CHAR, text
from sqlalchemy.dialects.postgresql import UUID as PG_UUID
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.orm import DeclarativeBase
from sqlalchemy.types import TypeDecorator
from app.config import get_settings
class GUID(TypeDecorator):
"""
Platform-independent GUID type.
Uses PostgreSQL's UUID type when available, otherwise uses CHAR(32) for SQLite.
Stores as stringified hex values in SQLite.
"""
impl = CHAR
cache_ok = True
def load_dialect_impl(self, dialect):
if dialect.name == 'postgresql':
return dialect.type_descriptor(PG_UUID(as_uuid=True))
else:
return dialect.type_descriptor(CHAR(32))
def process_bind_param(self, value, dialect):
if value is None:
return value
elif dialect.name == 'postgresql':
return value
else:
if isinstance(value, uuid.UUID):
return value.hex
else:
return uuid.UUID(value).hex
def process_result_value(self, value, dialect):
if value is None:
return value
elif dialect.name == 'postgresql':
return value
else:
if isinstance(value, uuid.UUID):
return value
return uuid.UUID(value)
settings = get_settings()
# Create async engine with production-ready pool settings
engine = create_async_engine(
settings.database_url,
echo=settings.debug,
future=True,
pool_size=20,
max_overflow=10,
pool_recycle=3600,
pool_pre_ping=True,
)
# Session factory
async_session_maker = async_sessionmaker(
engine,
class_=AsyncSession,
expire_on_commit=False,
)
class Base(DeclarativeBase):
"""Base class for all SQLAlchemy models."""
pass
async def get_db() -> AsyncSession:
"""
Dependency that provides a database session.
Yields a session and ensures it's closed after use.
"""
async with async_session_maker() as session:
try:
yield session
await session.commit()
except Exception:
await session.rollback()
raise
finally:
await session.close()
async def check_db_health() -> bool:
"""Check database connectivity by running a simple query."""
try:
async with engine.connect() as conn:
await conn.execute(text("SELECT 1"))
return True
except Exception:
return False
async def init_db() -> None:
"""Initialize database tables (for development only)."""
async with engine.begin() as conn:
await conn.run_sync(Base.metadata.create_all)
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