Fix neo4j sanitize (langchain-ai#16439)

Fix the sanitization bug and add an integration test

libs/community/langchain_community/graphs/neo4j_graph.py

@@ -160,7 +160,7 @@ def query(self, query: str, params: dict = {}) -> List[Dict[str, Any]]:
                 data = session.run(Query(text=query, timeout=self.timeout), params)
                 json_data = [r.data() for r in data]
                 if self.sanitize:
-                    json_data = value_sanitize(json_data)
+                    json_data = [value_sanitize(el) for el in json_data]
                 return json_data
             except CypherSyntaxError as e:
                 raise ValueError(f"Generated Cypher Statement is not valid\n{e}")

libs/community/tests/integration_tests/graphs/test_neo4j.py

@@ -88,3 +88,31 @@ def test_neo4j_timeout() -> None:
             e.code
             == "Neo.ClientError.Transaction.TransactionTimedOutClientConfiguration"
         )
+
+
+def test_neo4j_sanitize_values() -> None:
+    """Test that neo4j uses the timeout correctly."""
+    url = os.environ.get("NEO4J_URI")
+    username = os.environ.get("NEO4J_USERNAME")
+    password = os.environ.get("NEO4J_PASSWORD")
+    assert url is not None
+    assert username is not None
+    assert password is not None
+
+    graph = Neo4jGraph(url=url, username=username, password=password, sanitize=True)
+    # Delete all nodes in the graph
+    graph.query("MATCH (n) DETACH DELETE n")
+    # Create two nodes and a relationship
+    graph.query(
+        """
+        CREATE (la:LabelA {property_a: 'a'})
+        CREATE (lb:LabelB)
+        CREATE (lc:LabelC)
+        MERGE (la)-[:REL_TYPE]-> (lb)
+        MERGE (la)-[:REL_TYPE {rel_prop: 'abc'}]-> (lc)
+        """
+    )
+    graph.refresh_schema()
+
+    output = graph.query("RETURN range(0,130,1) AS result")
+    assert output == [{}]