Add database engine and session creation

backend/src/database.py

@@ -0,0 +1,29 @@
+from sqlmodel import SQLModel, create_engine, Session
+
+db_name = "database.db"
+db_connection_url = f"sqlite:///{db_name}"
+
+# Disable check_same_thread. Default is True, but FastAPI may use different threads for handling one request due to a
+# paused async function may resume in another thread. We will make sure that sessions do not get shared between
+# requests by injecting the session as dependency.
+connect_args = {"check_same_thread": False}
+
+# Connect to database
+engine = create_engine(db_connection_url, echo=True, connect_args=connect_args)
+
+
+def create_db_and_tables():
+    """Creates database and tables if they do not exist yet."""
+
+    SQLModel.metadata.create_all(engine)
+
+
+def get_session():
+    """Yields a database session. This method is used to inject a session into request handling functions.
+
+    Example:
+    async def my_route(*, session: Session = Depends(get_session), hero: HeroCreate)
+    """
+
+    with Session(engine) as session:
+        yield session

backend/src/main.py

@@ -4,6 +4,7 @@ import uvicorn
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
+from src import database
 from src.routes.projects import router as project_router
 from src.routes.tags import router as tag_router
 from src.routes.records import router as record_router
@@ -15,10 +16,11 @@ Welcome to the Juggl API.
 This API allows you to retrieve your timetracking data.
 """
 
+
 app = FastAPI(
     title="Juggl API",
     description=description,
-    contact={  # Contact information. See  https://fastapi.tiangolo.com/tutorial/metadata/
+    contact={  # Optional contact information. See https://fastapi.tiangolo.com/tutorial/metadata/
         "name": "Juggl Management",
         "url": "https://juggl.giller.dev/contact",
         "email": "help@juggl.giller.dev",
@@ -27,6 +29,7 @@ app = FastAPI(
 )
 """The main FastAPI instance"""
 
+
 # Enable CORS to allow requests from other domains/origins.
 # See https://en.wikipedia.org/wiki/Cross-origin_resource_sharing
 app.add_middleware(
@@ -39,6 +42,14 @@ app.add_middleware(
     allow_headers=["*"],
 )
 
+
+@app.on_event("startup")
+def on_startup():
+    """Code executed on HTTP server startup. Until now only creating databases and tables."""
+
+    database.create_db_and_tables()
+
+
 # Add subroutes
 app.include_router(project_router)
 app.include_router(tag_router)
@@ -57,11 +68,11 @@ def parse_args() -> argparse.Namespace:
     """Parses command line arguments on application startup."""
 
     parser = argparse.ArgumentParser(
-        description="Juggl Backend v2",
+        description="Juggl Backend API v2. Start a server listening on port.",
         formatter_class=argparse.ArgumentDefaultsHelpFormatter  # show default values
     )
     parser.add_argument("--dev", default=False, action=argparse.BooleanOptionalAction,
-                        help="Start a dev server with auto-reloading")
+                        help="Enable auto-reloading on file-save")
     parser.add_argument("--port", type=int, default=8192, help="Port on which the API should run")
     return parser.parse_args()