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378db2e1a5
- **Description:** Add `RedisChatMessageHistory ` rich docstrings. - **Issue:** the issue #21983 Co-authored-by: ccurme <chester.curme@gmail.com>
121 lines
3.6 KiB
Python
121 lines
3.6 KiB
Python
import json
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import logging
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from typing import List, Optional
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from langchain_core.chat_history import BaseChatMessageHistory
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from langchain_core.messages import (
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BaseMessage,
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message_to_dict,
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messages_from_dict,
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)
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from langchain_community.utilities.redis import get_client
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logger = logging.getLogger(__name__)
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class RedisChatMessageHistory(BaseChatMessageHistory):
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"""Chat message history stored in a Redis database.
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Setup:
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Install ``redis`` python package.
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.. code-block:: bash
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pip install redis
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Instantiate:
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.. code-block:: python
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from langchain_community.chat_message_histories import RedisChatMessageHistory
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history = RedisChatMessageHistory(
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session_id = "your-session-id",
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url="redis://your-host:your-port:your-database", # redis://localhost:6379/0
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)
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Add and retrieve messages:
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.. code-block:: python
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# Add single message
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history.add_message(message)
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# Add batch messages
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history.add_messages([message1, message2, message3, ...])
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# Add human message
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history.add_user_message(human_message)
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# Add ai message
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history.add_ai_message(ai_message)
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# Retrieve messages
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messages = history.messages
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""" # noqa: E501
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def __init__(
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self,
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session_id: str,
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url: str = "redis://localhost:6379/0",
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key_prefix: str = "message_store:",
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ttl: Optional[int] = None,
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):
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"""Initialize with a RedisChatMessageHistory instance.
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Args:
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session_id: str
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The ID for single chat session. Used to form keys with `key_prefix`.
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url: Optional[str]
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String parameter configuration for connecting to the redis.
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key_prefix: Optional[str]
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The prefix of the key, combined with `session id` to form the key.
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ttl: Optional[int]
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Set the expiration time of `key`, the unit is seconds.
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"""
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try:
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import redis
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except ImportError:
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raise ImportError(
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"Could not import redis python package. "
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"Please install it with `pip install redis`."
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)
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try:
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self.redis_client = get_client(redis_url=url)
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except redis.exceptions.ConnectionError as error:
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logger.error(error)
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self.session_id = session_id
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self.key_prefix = key_prefix
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self.ttl = ttl
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@property
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def key(self) -> str:
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"""Construct the record key to use"""
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return self.key_prefix + self.session_id
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@property
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def messages(self) -> List[BaseMessage]:
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"""Retrieve the messages from Redis"""
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_items = self.redis_client.lrange(self.key, 0, -1)
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items = [json.loads(m.decode("utf-8")) for m in _items[::-1]]
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messages = messages_from_dict(items)
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return messages
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@messages.setter
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def messages(self, messages: List[BaseMessage]) -> None:
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raise NotImplementedError(
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"Direct assignment to 'messages' is not allowed."
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" Use the 'add_messages' instead."
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)
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def add_message(self, message: BaseMessage) -> None:
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"""Append the message to the record in Redis"""
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self.redis_client.lpush(self.key, json.dumps(message_to_dict(message)))
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if self.ttl:
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self.redis_client.expire(self.key, self.ttl)
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def clear(self) -> None:
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"""Clear session memory from Redis"""
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self.redis_client.delete(self.key)
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