Skip to main content
`Ctrl`+`K`

#

# Source code for langchain.memory.chat_message_histories.redis

    import json
    import logging
    from typing import List, Optional

    from langchain.schema import (
        AIMessage,
        BaseChatMessageHistory,
        BaseMessage,
        HumanMessage,
        _message_to_dict,
        messages_from_dict,
    )

    logger = logging.getLogger(__name__)

    class RedisChatMessageHistory(BaseChatMessageHistory):
        def __init__(
            self,
            session_id: str,
            url: str = "redis://localhost:6379/0",
            key_prefix: str = "message_store:",
            ttl: Optional[int] = None,
        ):
            try:
                import redis
            except ImportError:
                raise ValueError(
                    "Could not import redis python package. "
                    "Please install it with `pip install redis`."
                )

            try:
                self.redis_client = redis.Redis.from_url(url=url)
            except redis.exceptions.ConnectionError as error:
                logger.error(error)

            self.session_id = session_id
            self.key_prefix = key_prefix
            self.ttl = ttl

        @property
        def key(self) -> str:
            """Construct the record key to use"""
            return self.key_prefix + self.session_id

        @property
        def messages(self) -> List[BaseMessage]:  # type: ignore
            """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

        def add_user_message(self, message: str) -> None:
            self.append(HumanMessage(content=message))

        def add_ai_message(self, message: str) -> None:
            self.append(AIMessage(content=message))

        def append(self, message: BaseMessage) -> None:
            """Append the message to the record in Redis"""
            self.redis_client.lpush(self.key, json.dumps(_message_to_dict(message)))
            if self.ttl:
                self.redis_client.expire(self.key, self.ttl)

        def clear(self) -> None:
            """Clear session memory from Redis"""
            self.redis_client.delete(self.key)