refine mindmap (#1817)

### What problem does this PR solve?

#1594
### Type of change

- [x] Refactoring

graphrag/index.py

@@ -21,6 +21,7 @@ from typing import List
 import networkx as nx
 from api.db import LLMType
 from api.db.services.llm_service import LLMBundle
+from api.db.services.user_service import TenantService
 from graphrag.community_reports_extractor import CommunityReportsExtractor
 from graphrag.entity_resolution import EntityResolution
 from graphrag.graph_extractor import GraphExtractor
@@ -30,6 +31,11 @@ from rag.utils import num_tokens_from_string
 
 
 def be_children(obj: dict, keyset:set):
+    if isinstance(obj, str):
+        obj = [obj]
+    if isinstance(obj, list):
+        for i in obj: keyset.add(i)
+        return [{"id": i, "children":[]} for i in obj]
     arr = []
     for k,v in obj.items():
         k = re.sub(r"\*+", "", k)
@@ -65,7 +71,8 @@ def graph_merge(g1, g2):
 
 
 def build_knowlege_graph_chunks(tenant_id: str, chunks: List[str], callback, entity_types=["organization", "person", "location", "event", "time"]):
-    llm_bdl = LLMBundle(tenant_id, LLMType.CHAT)
+    _, tenant = TenantService.get_by_id(tenant_id)
+    llm_bdl = LLMBundle(tenant_id, LLMType.CHAT, tenant.llm_id)
     ext = GraphExtractor(llm_bdl)
     left_token_count = llm_bdl.max_length - ext.prompt_token_count - 1024
     left_token_count = max(llm_bdl.max_length * 0.8, left_token_count)