mongodb[patch]: Make ObjectId JSON-serializable on generation (#21394)

libs/partners/mongodb/langchain_mongodb/vectorstores.py

@@ -16,6 +16,7 @@ from typing import (
 )
 
 import numpy as np
+from bson import ObjectId, json_util
 from langchain_core.documents import Document
 from langchain_core.embeddings import Embeddings
 from langchain_core.runnables.config import run_in_executor
@@ -210,9 +211,23 @@ class MongoDBAtlasVectorSearch(VectorStore):
             pipeline.extend(post_filter_pipeline)
         cursor = self._collection.aggregate(pipeline)  # type: ignore[arg-type]
         docs = []
+
+        def _make_serializable(obj: Dict[str, Any]) -> None:
+            for k, v in obj.items():
+                if isinstance(v, dict):
+                    _make_serializable(v)
+                elif isinstance(v, list) and v and isinstance(v[0], ObjectId):
+                    obj[k] = [json_util.default(item) for item in v]
+                elif isinstance(v, ObjectId):
+                    obj[k] = json_util.default(v)
+
         for res in cursor:
             text = res.pop(self._text_key)
             score = res.pop("score")
+            # Make every ObjectId found JSON-Serializable
+            # following format used in bson.json_util.loads
+            # e.g. loads('{"_id": {"$oid": "664..."}}') == {'_id': ObjectId('664..')} # noqa: E501
+            _make_serializable(res)
             docs.append((Document(page_content=text, metadata=res), score))
         return docs
 

libs/partners/mongodb/tests/unit_tests/test_vectorstores.py

@@ -1,6 +1,8 @@
+from json import dumps, loads
 from typing import Any, Optional
 
 import pytest
+from bson import ObjectId, json_util
 from langchain_core.documents import Document
 from langchain_core.embeddings import Embeddings
 from pymongo.collection import Collection
@@ -75,6 +77,11 @@ class TestMongoDBAtlasVectorSearch:
         output = vectorstore.similarity_search("", k=1)
         assert output[0].page_content == page_content
         assert output[0].metadata.get("c") == metadata
+        # Validate the ObjectId provided is json serializable
+        assert loads(dumps(output[0].page_content)) == output[0].page_content
+        assert loads(dumps(output[0].metadata)) == output[0].metadata
+        json_metadata = dumps(output[0].metadata)  # normal json.dumps
+        assert isinstance(json_util.loads(json_metadata)["_id"], ObjectId)
 
     def test_from_documents(
         self, embedding_openai: Embeddings, collection: MockCollection

libs/partners/mongodb/tests/utils.py

@@ -1,9 +1,9 @@
 from __future__ import annotations
 
-import uuid
 from copy import deepcopy
 from typing import Any, Dict, List, Mapping, Optional, cast
 
+from bson import ObjectId
 from langchain_core.callbacks.manager import (
     AsyncCallbackManagerForLLMRun,
     CallbackManagerForLLMRun,
@@ -162,7 +162,7 @@ class MockCollection(Collection):
 
     def insert_many(self, to_insert: List[Any], *args, **kwargs) -> InsertManyResult:  # type: ignore
         mongodb_inserts = [
-            {"_id": str(uuid.uuid4()), "score": 1, **insert} for insert in to_insert
+            {"_id": ObjectId(), "score": 1, **insert} for insert in to_insert
         ]
         self._data.extend(mongodb_inserts)
         return self._insert_result or InsertManyResult(