db engine

.env.template

@@ -0,0 +1 @@
+DATABASE_URL_DEFAULT = "sqlite:///finanz.db"

.gitignore

@@ -8,3 +8,6 @@ wheels/
 
 # Virtual environments
 .venv
+
+# Environment variables
+.env

src/db.py

@@ -0,0 +1,33 @@
+#!/bin/python
+
+import os
+from collections.abc import Generator
+from contextlib import contextmanager
+
+from sqlalchemy import Engine, create_engine
+from sqlalchemy.orm import Session, sessionmaker
+
+DATABASE_URL_DEFAULT = "sqlite:///finanz.db"
+
+
+def get_engine() -> Engine:
+    url = os.environ.get("DATABASE_URL", DATABASE_URL_DEFAULT)
+    return create_engine(url)
+
+
+def get_sessionmaker(engine: Engine | None = None) -> sessionmaker[Session]:
+    engine = engine or get_engine()
+    return sessionmaker(bind=engine)
+
+
+@contextmanager
+def get_session(engine: Engine | None = None) -> Generator[Session]:
+    session_factory = get_sessionmaker(engine)
+    session = session_factory()
+    try:
+        yield session
+    except Exception:
+        session.rollback()
+        raise
+    finally:
+        session.close()