Add DEMO feature to the project

services/demo_session/app/core/database.py

@@ -0,0 +1,61 @@
+"""
+Database connection management for Demo Session Service
+"""
+
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession, async_sessionmaker
+from sqlalchemy.pool import NullPool
+import structlog
+
+from .config import settings
+
+logger = structlog.get_logger()
+
+
+class DatabaseManager:
+    """Database connection manager"""
+
+    def __init__(self, database_url: str = None):
+        self.database_url = database_url or settings.DATABASE_URL
+        self.engine = None
+        self.session_factory = None
+
+    def initialize(self):
+        """Initialize database engine and session factory"""
+        self.engine = create_async_engine(
+            self.database_url,
+            echo=settings.DEBUG,
+            poolclass=NullPool,
+            pool_pre_ping=True
+        )
+
+        self.session_factory = async_sessionmaker(
+            self.engine,
+            class_=AsyncSession,
+            expire_on_commit=False,
+            autocommit=False,
+            autoflush=False
+        )
+
+        logger.info("Database manager initialized", database_url=self.database_url.split("@")[-1])
+
+    async def close(self):
+        """Close database connections"""
+        if self.engine:
+            await self.engine.dispose()
+            logger.info("Database connections closed")
+
+    async def get_session(self) -> AsyncSession:
+        """Get database session"""
+        if not self.session_factory:
+            self.initialize()
+        async with self.session_factory() as session:
+            yield session
+
+
+db_manager = DatabaseManager()
+
+
+async def get_db() -> AsyncSession:
+    """Dependency for FastAPI"""
+    async for session in db_manager.get_session():
+        yield session