fix: using embd which user configured at knowledgebase (#1163)

### What problem does this PR solve?
as title
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)

api/db/services/document_service.py

@@ -182,6 +182,19 @@ class DocumentService(CommonService):
             return
         return docs[0]["tenant_id"]
 
+    @classmethod
+    @DB.connection_context()
+    def get_embd_id(cls, doc_id):
+        docs = cls.model.select(
+            Knowledgebase.embd_id).join(
+            Knowledgebase, on=(
+                Knowledgebase.id == cls.model.kb_id)).where(
+                cls.model.id == doc_id, Knowledgebase.status == StatusEnum.VALID.value)
+        docs = docs.dicts()
+        if not docs:
+            return
+        return docs[0]["embd_id"]
+    
     @classmethod
     @DB.connection_context()
     def get_doc_id_by_doc_name(cls, doc_name):