Phase 4 구현 완료: Neo4j 벡터 검색 + 그래프 저장소

ontology_platform/ont_platform/api/db_deps.py

@@ -0,0 +1,49 @@
+"""Database dependencies for FastAPI."""
+
+from typing import Generator
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import Session, sessionmaker
+
+from ont_platform.config import load_settings
+
+# Initialize database engine (lazy singleton)
+_engine = None
+_SessionLocal = None
+
+
+def get_db_engine():
+    """Get or create database engine."""
+    global _engine
+    if _engine is None:
+        settings = load_settings()
+        database_url = settings.database_url
+        _engine = create_engine(
+            database_url,
+            connect_args={"timeout": 30} if "sqlite" in database_url else {},
+            pool_pre_ping=True,
+            echo=False,
+        )
+    return _engine
+
+
+def get_session_factory():
+    """Get or create session factory."""
+    global _SessionLocal
+    if _SessionLocal is None:
+        engine = get_db_engine()
+        _SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+    return _SessionLocal
+
+
+def get_db() -> Generator[Session, None, None]:
+    """FastAPI dependency for database session."""
+    SessionLocal = get_session_factory()
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+__all__ = ["get_db", "get_db_engine", "get_session_factory"]