添加GraphRAG后端

backend/graph_query.py

@@ -0,0 +1,48 @@
+import os
+from neo4j import GraphDatabase
+from dotenv import load_dotenv
+
+load_dotenv()
+
+_driver = None
+
+
+def get_driver():
+    global _driver
+    if _driver is None:
+        uri = os.getenv("NEO4J_URI", "bolt://localhost:7687")
+        user = os.getenv("NEO4J_USER", "neo4j")
+        password = os.getenv("NEO4J_PASSWORD", "dtmap2024")
+        _driver = GraphDatabase.driver(uri, auth=(user, password))
+    return _driver
+
+
+def run_query(cypher: str, params: dict = None) -> list[dict]:
+    driver = get_driver()
+    with driver.session() as session:
+        result = session.run(cypher, params or {})
+        rows = []
+        for record in result:
+            row = {}
+            for key in record.keys():
+                val = record[key]
+                # Node/Relationship → plain dict
+                if hasattr(val, "_properties"):
+                    row[key] = dict(val._properties)
+                else:
+                    row[key] = val
+            rows.append(row)
+        return rows
+
+
+def get_graph_stats() -> dict:
+    driver = get_driver()
+    stats = {}
+    with driver.session() as session:
+        for label in ["Character", "Location", "Faction", "Event"]:
+            r = session.run(f"MATCH (n:{label}) RETURN count(n) AS cnt")
+            stats[f"{label}_count"] = r.single()["cnt"]
+        for rel in ["VISITED", "CONTROLS", "HAS_MEMBER", "LEADS", "OCCURRED_AT"]:
+            r = session.run(f"MATCH ()-[r:{rel}]->() RETURN count(r) AS cnt")
+            stats[f"{rel}_count"] = r.single()["cnt"]
+    return stats