Adding in sql.py, setting up connection and session management.

Signed-off-by: Cliff Hill <xlorep@darkhelm.org>

backend/src/backend/sql.py

@@ -0,0 +1,64 @@
+"""SQL code for the Numinar coding project backend."""
+
+from collections.abc import Coroutine
+from functools import wraps
+from typing import Any
+from typing import Callable
+from typing import TypeVar
+
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.ext.asyncio import async_sessionmaker
+from sqlalchemy.ext.asyncio import create_async_engine
+from sqlalchemy.orm import sessionmaker
+from sqlmodel import SQLModel
+
+from backend import config
+
+
+# from backend import models
+
+
+T = TypeVar("T")
+
+sync_maker = sessionmaker(
+    autocommit=False,
+    autoflush=False,
+    expire_on_commit=False,
+)
+async_maker = async_sessionmaker(
+    autocommit=False,
+    autoflush=False,
+    expire_on_commit=False,
+    sync_session_class=sync_maker,
+)
+
+engine = create_async_engine(
+    config("DATABASE_URL"), echo=config("ENVIRONMENT") == "development"
+)
+
+
+async def sessionize(
+    func: Callable[..., Coroutine[Any, Any, T]],
+) -> Callable[..., Coroutine[Any, Any, T]]:
+    """Decorate a sql function and inject a session if it doesn't exist.
+
+    This checks the function signature for a `session` parameter. If it does
+    not exist, it creates a new session and passes it to the function.
+    """
+
+    @wraps(func)
+    async def wrapper(
+        *args: Any, session: AsyncSession | None = None, **kwargs: Any
+    ) -> T:
+        if session is None:
+            async with async_maker() as session:
+                return await func(*args, session=session, **kwargs)
+        else:
+            return await func(*args, session=session, **kwargs)
+
+    return wrapper
+
+
+def create_db_and_tables() -> None:
+    """Create the database and tables."""
+    SQLModel.metadata.create_all(engine.sync_engine)