community[patch]: Bug Neo4j VectorStore when having multiple indexes …

…the sort is not working and the store that returned is random (langchain-ai#17396)

Bug fix: when having multiple indexes the sort is not working and the
store that returned is random.
The following small fix resolves the issue.

libs/community/langchain_community/vectorstores/neo4j_vector.py

@@ -77,7 +77,7 @@ def sort_by_index_name(
     lst: List[Dict[str, Any]], index_name: str
 ) -> List[Dict[str, Any]]:
     """Sort first element to match the index_name if exists"""
-    return sorted(lst, key=lambda x: x.get("index_name") != index_name)
+    return sorted(lst, key=lambda x: x.get("name") != index_name)
 
 
 def remove_lucene_chars(text: str) -> str:

libs/community/tests/integration_tests/vectorstores/test_neo4jvector.py

@@ -678,3 +678,46 @@ def test_hybrid_score_normalization() -> None:
     # Both FT and Vector must return 1.0 score
     assert output == [{"text": "foo", "score": 1.0}, {"text": "foo", "score": 1.0}]
     drop_vector_indexes(docsearch)
+
+
+def test_index_fetching() -> None:
+    """testing correct index creation and fetching"""
+    embeddings = FakeEmbeddings()
+
+    def create_store(
+        node_label: str, index: str, text_properties: List[str]
+    ) -> Neo4jVector:
+        return Neo4jVector.from_existing_graph(
+            embedding=embeddings,
+            url=url,
+            username=username,
+            password=password,
+            index_name=index,
+            node_label=node_label,
+            text_node_properties=text_properties,
+            embedding_node_property="embedding",
+        )
+
+    def fetch_store(index_name: str) -> Neo4jVector:
+        store = Neo4jVector.from_existing_index(
+            embedding=embeddings,
+            url=url,
+            username=username,
+            password=password,
+            index_name=index_name,
+        )
+        return store
+
+    # create index 0
+    index_0_str = "index0"
+    create_store("label0", index_0_str, ["text"])
+
+    # create index 1
+    index_1_str = "index1"
+    create_store("label1", index_1_str, ["text"])
+
+    index_1_store = fetch_store(index_1_str)
+    assert index_1_store.index_name == index_1_str
+
+    index_0_store = fetch_store(index_0_str)
+    assert index_0_store.index_name == index_0_str