Initial commit of mtgonline project

backend/app/core/database.py

@@ -0,0 +1,42 @@
+"""
+Database engine and session management.
+
+Provides async SQLAlchemy engine and session factory for dependency injection.
+"""
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession, async_sessionmaker
+from sqlalchemy.orm import DeclarativeBase
+from app.core.settings import get_settings
+
+settings = get_settings()
+
+engine = create_async_engine(
+    settings.DATABASE_URL,
+    echo=settings.DEBUG,
+    pool_pre_ping=True,
+    pool_size=20,
+    max_overflow=10,
+)
+
+async_session = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+class Base(DeclarativeBase):
+    """Base class for all ORM models."""
+    pass
+
+
+async def get_db() -> AsyncSession:
+    """FastAPI dependency that provides a database session."""
+    async with async_session() as session:
+        try:
+            yield session
+            await session.commit()
+        except Exception:
+            await session.rollback()
+            raise
+        finally:
+            await session.close()