From f076d2e841a11342ef5ddc8f9efdd42a46811190 Mon Sep 17 00:00:00 2001
From: Mathias Scheider <mathias2784@web.de>
Date: Fri, 4 Sep 2026 14:41:29 +0200
Subject: [PATCH] db engine

---
 .env.template |  1 +
 .gitignore    |  3 +++
 src/db.py     | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 .env.template
 create mode 100644 src/db.py

diff --git a/.env.template b/.env.template
new file mode 100644
index 0000000..178a635
--- /dev/null
+++ b/.env.template
@@ -0,0 +1 @@
+DATABASE_URL_DEFAULT = "sqlite:///finanz.db"
diff --git a/.gitignore b/.gitignore
index 505a3b1..303cc54 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,3 +8,6 @@ wheels/
 
 # Virtual environments
 .venv
+
+# Environment variables
+.env
diff --git a/src/db.py b/src/db.py
new file mode 100644
index 0000000..310e399
--- /dev/null
+++ b/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()