community[patch]: chat message history mypy fixes #17048 (#20114)

Relates [#17048]
Description : Applied fix to redis and neo4j file.

Error was : `Cannot override writeable attribute with read-only
property`

fix with the same solution of
[[langchain/libs/community/langchain_community/chat_message_histories/elasticsearch.py](https://github.com/langchain-ai/langchain/blob/d5c412b0a9a8af02754de60f93d93c3efa33ccdb/libs/community/langchain_community/chat_message_histories/elasticsearch.py#L170-L175)]

---------

Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>
Co-authored-by: Chester Curme <chester.curme@gmail.com>

Author: 3 people

libs/community/langchain_community/chat_message_histories/neo4j.py

@@ -76,7 +76,7 @@ def __init__(
         ).summary
 
     @property
-    def messages(self) -> List[BaseMessage]:  # type: ignore
+    def messages(self) -> List[BaseMessage]:
         """Retrieve the messages from Neo4j"""
         query = (
             f"MATCH (s:`{self._node_label}`)-[:LAST_MESSAGE]->(last_message) "
@@ -92,6 +92,13 @@ def messages(self) -> List[BaseMessage]:  # type: ignore
         messages = messages_from_dict([el["result"] for el in records])
         return messages
 
+    @messages.setter
+    def messages(self, messages: List[BaseMessage]) -> None:
+        raise NotImplementedError(
+            "Direct assignment to 'messages' is not allowed."
+            " Use the 'add_messages' instead."
+        )
+
     def add_message(self, message: BaseMessage) -> None:
         """Append the message to the record in Neo4j"""
         query = (

libs/community/langchain_community/chat_message_histories/redis.py

@@ -47,13 +47,20 @@ def key(self) -> str:
         return self.key_prefix + self.session_id
 
     @property
-    def messages(self) -> List[BaseMessage]:  # type: ignore
+    def messages(self) -> List[BaseMessage]:
         """Retrieve the messages from Redis"""
         _items = self.redis_client.lrange(self.key, 0, -1)
         items = [json.loads(m.decode("utf-8")) for m in _items[::-1]]
         messages = messages_from_dict(items)
         return messages
 
+    @messages.setter
+    def messages(self, messages: List[BaseMessage]) -> None:
+        raise NotImplementedError(
+            "Direct assignment to 'messages' is not allowed."
+            " Use the 'add_messages' instead."
+        )
+
     def add_message(self, message: BaseMessage) -> None:
         """Append the message to the record in Redis"""
         self.redis_client.lpush(self.key, json.dumps(message_to_dict(message)))