fix:bug

backend/app/db.py

@@ -0,0 +1,38 @@
+import os
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, DeclarativeBase
+
+
+class Base(DeclarativeBase):
+    """Base class for all ORM models."""
+
+
+def get_database_url() -> str:
+    """
+    DATABASE_URL is configurable via env, default to local SQLite file.
+    Example: sqlite:///./data/ops_core.db
+    """
+    return os.getenv("DATABASE_URL", "sqlite:///./data/ops_core.db")
+
+
+DATABASE_URL = get_database_url()
+
+# For SQLite, check_same_thread=False is required when used with FastAPI / threads.
+engine = create_engine(
+    DATABASE_URL,
+    connect_args={"check_same_thread": False} if DATABASE_URL.startswith("sqlite") else {},
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+
+def get_db():
+    """
+    FastAPI dependency to provide a DB session.
+    """
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+