community: Retry retriable errors in Neo4j (#26211)

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/community/langchain_community/graphs/neo4j_graph.py

@@ -411,7 +411,9 @@ class Neo4jGraph(GraphStore):
         return self.structured_schema
 
     def query(
-        self, query: str, params: dict = {}, retry_on_session_expired: bool = True
+        self,
+        query: str,
+        params: dict = {},
     ) -> List[Dict[str, Any]]:
         """Query Neo4j database.
 
@@ -423,26 +425,44 @@ class Neo4jGraph(GraphStore):
             List[Dict[str, Any]]: The list of dictionaries containing the query results.
         """
         from neo4j import Query
-        from neo4j.exceptions import CypherSyntaxError, SessionExpired
+        from neo4j.exceptions import Neo4jError
 
-        with self._driver.session(database=self._database) as session:
-            try:
-                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(el) for el in json_data]
-                return json_data
-            except CypherSyntaxError as e:
-                raise ValueError(f"Generated Cypher Statement is not valid\n{e}")
-            except (
-                SessionExpired
-            ) as e:  # Session expired is a transient error that can be retried
-                if retry_on_session_expired:
-                    return self.query(
-                        query, params=params, retry_on_session_expired=False
+        try:
+            data, _, _ = self._driver.execute_query(
+                Query(text=query, timeout=self.timeout),
+                database=self._database,
+                parameters_=params,
+            )
+            json_data = [r.data() for r in data]
+            if self.sanitize:
+                json_data = [value_sanitize(el) for el in json_data]
+            return json_data
+        except Neo4jError as e:
+            if not (
+                (
+                    (  # isCallInTransactionError
+                        e.code == "Neo.DatabaseError.Statement.ExecutionFailed"
+                        or e.code
+                        == "Neo.DatabaseError.Transaction.TransactionStartFailed"
                     )
-                else:
-                    raise e
+                    and "in an implicit transaction" in e.message
+                )
+                or (  # isPeriodicCommitError
+                    e.code == "Neo.ClientError.Statement.SemanticError"
+                    and (
+                        "in an open transaction is not possible" in e.message
+                        or "tried to execute in an explicit transaction" in e.message
+                    )
+                )
+            ):
+                raise
+        # fallback to allow implicit transactions
+        with self._driver.session() as session:
+            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(el) for el in json_data]
+            return json_data
 
     def refresh_schema(self) -> None:
         """

libs/community/langchain_community/vectorstores/neo4j_vector.py

@@ -595,11 +595,8 @@ class Neo4jVector(VectorStore):
         query: str,
         *,
         params: Optional[dict] = None,
-        retry_on_session_expired: bool = True,
     ) -> List[Dict[str, Any]]:
-        """
-        This method sends a Cypher query to the connected Neo4j database
-        and returns the results as a list of dictionaries.
+        """Query Neo4j database with retries and exponential backoff.
 
         Args:
             query (str): The Cypher query to execute.
@@ -608,24 +605,38 @@ class Neo4jVector(VectorStore):
         Returns:
             List[Dict[str, Any]]: List of dictionaries containing the query results.
         """
-        from neo4j.exceptions import CypherSyntaxError, SessionExpired
+        from neo4j import Query
+        from neo4j.exceptions import Neo4jError
 
         params = params or {}
-        with self._driver.session(database=self._database) as session:
-            try:
-                data = session.run(query, params)
-                return [r.data() for r in data]
-            except CypherSyntaxError as e:
-                raise ValueError(f"Cypher Statement is not valid\n{e}")
-            except (
-                SessionExpired
-            ) as e:  # Session expired is a transient error that can be retried
-                if retry_on_session_expired:
-                    return self.query(
-                        query, params=params, retry_on_session_expired=False
+        try:
+            data, _, _ = self._driver.execute_query(
+                query, database=self._database, parameters_=params
+            )
+            return [r.data() for r in data]
+        except Neo4jError as e:
+            if not (
+                (
+                    (  # isCallInTransactionError
+                        e.code == "Neo.DatabaseError.Statement.ExecutionFailed"
+                        or e.code
+                        == "Neo.DatabaseError.Transaction.TransactionStartFailed"
                     )
-                else:
-                    raise e
+                    and "in an implicit transaction" in e.message
+                )
+                or (  # isPeriodicCommitError
+                    e.code == "Neo.ClientError.Statement.SemanticError"
+                    and (
+                        "in an open transaction is not possible" in e.message
+                        or "tried to execute in an explicit transaction" in e.message
+                    )
+                )
+            ):
+                raise
+        # Fallback to allow implicit transactions
+        with self._driver.session() as session:
+            data = session.run(Query(text=query), params)
+            return [r.data() for r in data]
 
     def verify_version(self) -> None:
         """