Source code for langchain_community.chat_message_histories.file

import json
from pathlib import Path
from typing import List, Optional

from langchain_core.chat_history import (
    BaseChatMessageHistory,
)
from langchain_core.messages import BaseMessage, messages_from_dict, messages_to_dict


[docs]class FileChatMessageHistory(BaseChatMessageHistory): """Chat message history that stores history in a local file."""
[docs] def __init__( self, file_path: str, *, encoding: Optional[str] = None, ensure_ascii: bool = True, ) -> None: """Initialize the file path for the chat history. Args: file_path: The path to the local file to store the chat history. encoding: The encoding to use for file operations. Defaults to None. ensure_ascii: If True, escape non-ASCII in JSON. Defaults to True. """ self.file_path = Path(file_path) self.encoding = encoding self.ensure_ascii = ensure_ascii if not self.file_path.exists(): self.file_path.touch() self.file_path.write_text( json.dumps([], ensure_ascii=self.ensure_ascii), encoding=self.encoding )
@property def messages(self) -> List[BaseMessage]: # type: ignore """Retrieve the messages from the local file""" items = json.loads(self.file_path.read_text(encoding=self.encoding)) messages = messages_from_dict(items) return messages
[docs] def add_message(self, message: BaseMessage) -> None: """Append the message to the record in the local file""" messages = messages_to_dict(self.messages) messages.append(messages_to_dict([message])[0]) self.file_path.write_text( json.dumps(messages, ensure_ascii=self.ensure_ascii), encoding=self.encoding )
[docs] def clear(self) -> None: """Clear session memory from the local file""" self.file_path.write_text( json.dumps([], ensure_ascii=self.ensure_ascii), encoding=self.encoding )