Remove PostgreSQL and move to SQLite3

backend/app/db.py

@@ -1,10 +1,25 @@
 import os
+from pathlib import Path
+
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker, DeclarativeBase
 
-DATABASE_URL = os.environ["DATABASE_URL"]
+DATABASE_URL = os.getenv("DATABASE_URL", "sqlite:///./data/cluedo.db")
 
-engine = create_engine(DATABASE_URL, pool_pre_ping=True)
+engine_options = {"pool_pre_ping": True}
+
+if DATABASE_URL.startswith("sqlite"):
+    # SQLite does not allow connections to be used from another thread by
+    # default. FastAPI/SQLAlchemy may use a connection across request threads.
+    engine_options["connect_args"] = {"check_same_thread": False}
+
+    # Make the parent directory available for the default local database.
+    if DATABASE_URL.startswith("sqlite:///"):
+        sqlite_path = DATABASE_URL.removeprefix("sqlite:///")
+        if sqlite_path not in (":memory:", ""):
+            Path(sqlite_path).expanduser().parent.mkdir(parents=True, exist_ok=True)
+
+engine = create_engine(DATABASE_URL, **engine_options)
 SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)
 
 class Base(DeclarativeBase):
@@ -16,4 +31,4 @@ def get_db():
         yield db
     finally:
         db.close()
-        
+